TRANSACTION AUTHENTICATION

Technical field The present disclosure relates to a method for an electronic device to generate and provide authentication data relating to a transaction, a method for an authorisation system to authenticate a transaction using authentication data generated by a software program on an electronic device, and apparatus and computer programs for carrying out such methods. The present disclosure also relates to a method for an electronic device to enable a terminal to perform an authentication operation when the electronic device is executing a software program to perform a transaction via the terminal, a method for enabling an electronic device to carry out such a method, and apparatus and computer programs for carrying out such methods.

The present disclosure also relates to a method for a mobile electronic device to generate and provide an output relating to a financial transaction, a method for configuring a mobile electronic device to carry out such a method, apparatus and computer programs for carrying out said methods, and a method for creating a system for performing a

cryptographic process to generate a result.

Background

It is known to provide a virtual payment product (for example a virtual credit card or a virtual debit card) on an electronic device (such as a mobile telephone) to enable the electronic device to perform a contactless payment process (for example using near field

communications (NFC)). Current implementations of this use a hardware device, known as a Secure Element (SE) - the SE could be, for example, a subscriber identity module (SIM), a so-called "Chip in Handset", a MicroSD card, etc. The SE stores data relating to the virtual payment product (such as a virtual card number). SEs are seen to provide protection of payment data with the same level of security as a standard physical "chip and PIN" card as the SE has the same security properties such as hardware, operating system and procedures to provision the payment product. However, utilising SEs has a number of problems and undesirable constraints. These may include: a large upfront investment cost; a high cost of ownership; and a large variety and number of different entities who are required to work in synchronisation to effect the technology, particularly when those entities may wish to keep their processes

secret/secured.

Furthermore, managing SEs may be very complicated as a consequence of at least one of: unstable technology across the whole system due to continual technological evolution; the technology across the whole system being controlled by multiple different standards bodies (for example, EMVco, GSMA, NFC Forum, GlobalPlatform); non-standard deployments being used on the SEs (for example in Mobile Network Operators (MNOs), Wallets, Registration, Eligibility and Operations); the need continually to cater for new models of electronic devices, SIMs, Operating Systems and standards; and sensitivities over customer ownership, for example with Wallets, and loss of end to end customer experience.

Summary

It would, therefore, be desirable to be able to address one or more of the above-mentioned problems.

In a first aspect of the present disclosure there is provided a method for an electronic device to generate and provide authentication data relating to a transaction, the method comprising a software program that is executing on a processor of the electronic device performing the steps of: receiving data relating to the transaction from a terminal;

generating authentication data based, at least in part, on (a) the data relating to the transaction and (b) device information, wherein the device information comprises one or both of: (i) information on the electronic device suitable for identifying the electronic device and (ii) information specifying at least part of a configuration of the electronic device; and outputting authentication information for provision to the terminal, wherein the

authentication information comprises at least the authentication data.

The authentication information may further comprise an indication that the authentication data was generated using the software program. Additionally, or alternatively, the authentication information may further comprise an indication of a process by which the authentication data was generated.

Preferably, the electronic device may store a counter, wherein the authentication data is generated based, at least in part, on the counter, and wherein the method comprises the software program incrementing the counter.

Preferably, the software program may generate a first session key based, at least in part, on the counter, wherein the authentication data is generated using at least a first cryptographic algorithm and the first session key.

The first session key may be generated using at least a second cryptographic algorithm and a device key that is stored as part of the software program on the electronic device. Preferably, the authentication data is generated using at least a third cryptographic algorithm and a device key that is stored as part of the software program on the electronic device.

The device key may be based, at least in part, on at least part of the information suitable for identifying the electronic device.

The method may further comprise the software program: receiving a PIN entered by a user of the electronic device; and generating PIN authentication data based, at least in part, on the PIN; wherein the authentication information is based, at least in part, on the PIN authentication data.

The software program may detect, based on the data relating to the transaction, whether the transaction satisfies a predetermined criterion, wherein the steps of receiving a PIN and generating PIN authentication data are performed if it is determined that the transaction satisfies the predetermined criterion.

The predetermined criterion may be that a transaction value for the transaction exceeds a predetermined threshold and/or that the data relating to the transaction requires that a PIN is received from the user. The authentication data may be generated based at least in part on the PIN authentication data.

The PIN authentication data may comprise at least part of a message authentication code based, at least in part, on the PIN.

Preferably, the PIN authentication data may be generated using at least a fourth cryptographic algorithm and a second session key. The software program may generate the second session key based, at least in part, on an initialisation vector stored as part of the software program.

The second session key may be generated using at least a fifth cryptographic algorithm and the first session key.

Preferably, the PIN authentication data is generated using at least a sixth cryptographic algorithm and the authentication data.

Preferably, the authentication data may comprise at least part of a message authentication code based, at least in part, on (a) the data relating to the transaction and (b) the device information on the electronic device suitable for identifying the electronic device.

The information on the electronic device suitable for identifying the electronic device may be based, at least in part, on at least one of a device MAC address; and/or a device IMEI, and/or wherein the information specifying at least part of a configuration of the electronic device is based, at least in part, on at least one of: the whole or a part of an operating system of the device; a version or type of the electronic device; and/or a mobile operating system application software token provided by the platform application store stored on the electronic device.

In a further aspect of the present disclosure, there is provided an electronic device comprising: a processor; and a memory storing a software program, wherein the software program, when executed by the processor, causes the processor to perform at least part of the method described above. In a further aspect of the present disclosure, there is provided a software program configured to perform at least part of the method described above when executed on a processor of an electronic device.

In a second aspect of the present disclosure, there is provided a method for an

authorisation system to authenticate a transaction using authentication data generated by a software program on an electronic device, wherein the authorisation system is configured to store data associated with the software program on the electronic device, the method comprising the authorisation system performing the steps of: receiving authentication information generated by the electronic device, wherein the authentication information comprises authentication data and data relating to the transaction; obtaining authentication process data using the stored data associated with the software program on the electronic device, the authentication process data being based, at least in part on, device information, wherein the device information comprises one or both of: (i) information suitable for identifying the electronic device and (ii) information specifying at least part of a

configuration of the electronic device; and performing an authentication process on the data relating to the transaction using the authentication data and the authentication process data.

The authentication information may further comprise an indication that the authentication data was generated using the software program on the electronic device, and wherein the indication is used in the step of performing an authentication process to determine which authentication process to perform.

The indication may further identify the process by which the authentication data was generated by the software program on the electronic device.

The data relating to the transaction may comprise a counter, and wherein the

authentication process comprises: generating a first session key based, at least in part, on the counter, and; generating test data based, at least in part, on the data relating to the transaction using at least a first cryptographic algorithm and the first session key, wherein the test data is for comparison with the authentication data. The authentication process data may be based, at least in part, on a device key associated with the software program on the electronic device, and wherein the first session key is generated using at least a second cryptographic algorithm and the device key. Preferably, the authentication process comprises generating test data based, at least in part, on the data relating to the transaction using at least a third cryptographic algorithm and a device key associated with the software program on the electronic device.

The method may comprise the authorisation system: obtaining, from a database, a PIN that is associated with a virtual transaction card provisioned on the software program on the electronic device, wherein the authentication process comprises: generating PIN

authentication data based, at least in part, on the PIN, and; generating test data based, at least in part, on the PIN authentication data, wherein the test data is for comparison with the authentication data.

The method may comprise the authorisation system: detecting, based on the data relating to the transaction, whether the transaction satisfies a predetermined criterion, wherein the steps of obtaining the PIN, generating PIN authentication data and generating test data based, at least in part, on the PIN authentication data are performed if it is determined that the transaction satisfies the predetermined criterion.

The predetermined criterion may be that a transaction value exceeds a predetermined threshold and/or that a flag indicates that a PIN was entered by a user of the electronic device.

The PIN authentication data may comprise at least part of a message authentication code based, at least in part, on the PIN.

The PIN authentication data may be generated using at least a fourth cryptographic algorithm and a second session key.

The authentication process data may further comprise an initialisation vector associated with the software program on the electronic device, and wherein the second session key is based, at least in part, on the initialisation vector. The second session key may be generated using at least a fifth cryptographic algorithm and the first session key.

The authentication data may comprise at least part of a message authentication code.

In a further aspect of the present disclosure, there is provided an authorisation system configured to perform at least part of the method described above.

In a further aspect of the present disclosure, there is provided a software program configured to perform at least part of the method described above.

In a further aspect of the present disclosure, there is provided a method for an electronic device to obtain the software program relating to the first aspect of the present disclosure, the method comprising the electronic device performing the steps of: outputting device information, wherein the device information comprises one or both of: (i) information on the electronic device suitable for identifying the electronic device and (ii) information specifying at least part of a configuration of the electronic device for provision to a provisioning system; receiving from the provisioning system at least part of the software program of claim 19; and storing the received at least part of the software program in a memory of the electronic device.

In a further aspect of the present disclosure, there is provided an electronic device configured to perform the method described above. In a further aspect of the present disclosure, there is provided a method for a provisioning system to provide the software program relating to the second aspect of the present disclosure to an electronic device, the method comprising the provisioning system performing the steps: receiving device information, wherein the device information comprises one or both of: (i) information suitable for identifying the electronic device and (ii) information specifying at least part of a configuration of the electronic device; generating at least part of the software program; outputting the at least part of the software program for provision to the electronic device; and storing data in a database, the stored data being stored as being associated with the at least part of the software program provided to the electronic device, the stored data being suitable for an authorisation system to obtain authentication process data, wherein the authentication process data is based, at least in part, on the device information.

The at least part of the software program may comprise a device key, wherein the authentication process data is based, at least in part, on the device key.

The step of generating at least part of the software program may comprise: generating the device key based, at least in part, on the device information. The at least part of the software program may comprise an initialisation vector, wherein the authentication process data is based, at least in part, on the initialisation vector.

In a further aspect of the present disclosure, there is provided a provisioning system configured to perform at least part of the method described above.

In a further aspect of the present disclosure, there is provided a software program configured to perform at least part of the method described above when executed on a processor of the provisioning system. In a third aspect of the present disclosure, there is provided a method for an electronic device to enable a terminal to perform an authentication operation when the electronic device is executing a software program to perform a transaction via the terminal, the method comprising the software program performing the steps of: in response to receiving a communication related to the transaction from the terminal, generating a response that comprises: (a) one or more items of information for use in processing the transaction, wherein at least one of the one or more items of information comprises first verification data; (b) a digital signature generated by the software program based on at least one of the one or more items of information; and (c) a digital certificate to facilitate the terminal to verify the digital signature; and providing the response to the terminal; wherein the first verification data comprises one or both of: (a) device information that comprises one or both of (i) information on the electronic device suitable for identifying the electronic device and (ii) information specifying at least part of a configuration of the electronic device; and (b) an indicator that is set to indicate that the software program is invalid; and wherein the digital certificate comprises second verification data for use by the terminal to verify the first verification data. At least part of the second verification data may equal the whole of the first verification data or equals a corresponding part of the first verification data. Additionally, or alternatively, at least part of the second verification data may be a hash of the whole of the first verification data or is a hash of a corresponding part of the first verification data.

The information on the electronic device may be suitable for identifying the electronic device is based, at least in part, on at least one of: a device MAC address; a device IMEI; and a serial number of the electronic device.

The information specifying at least part of a configuration of the electronic device may be based, at least in part, on at least one of: the whole or a part of an operating system of the device; a version or type of the electronic device; and/or a mobile operating system application software token, provided by a platform application store, stored on the electronic device.

At least one of the one or more items of information may comprise one or more of:

information relating to the software program; information relating to a virtual payment product provided by the software program; and information relating to the transaction.

The information relating to a virtual payment product provided by the software program may comprise one or more of an account number associated with the virtual payment product, an expiry date for the virtual payment product and/or an issue date for the virtual payment product.

The indicator may be an expiry date for the software program and the indicator has been set to represent an expired expiry date.

The terminal may be arranged, upon detection that the indicator has been set to indicate that the software program is invalid, to either (a) initiate a subsequent authentication process involving an authorisation system with which the terminal is in communication or (b) decline the transaction. In a further aspect of the present disclosure, there is provided an electronic device comprising: a processor; and a memory storing a software program, wherein the software program, when executed by the processor, causes the processor to perform at least part of the method of the above described third aspect of the present disclosure.

In a further aspect of the present disclosure, there is provided a software program configured to perform at least part of the method of the above described third aspect of the present disclosure when executed on a processor of an electronic device. In a further aspect of the present disclosure, there is provided a method for enabling an electronic device to enable a terminal to perform an authentication operation when the electronic device is performing a transaction via the terminal, the method comprising a provisioning system performing the steps of: generating the above described software program for use by the electronic device in performing the transaction; generating a digital certificate associated with the software program, wherein the digital certificate comprises second verification data, the second verification data for use by the terminal to verify first verification data that the software program provides to the terminal when the electronic device is executing the software program to perform the transaction; wherein the first verification data comprises one or both of: (a) device information that comprises one or both of (i) information suitable for identifying the electronic device and (ii) information specifying at least part of a configuration of the electronic device; and (b) an indicator that is set to indicate that the software program is invalid; outputting the software program and the digital certificate for provision to the electronic device. The above described method may further comprise generating at least part of the second verification as being equal to the whole of the first verification data or as being equal to a corresponding part of the first verification data.

The above described method may additionally, or alternatively, further comprise generating at least part of the second verification as a hash of the whole of the first verification data or as a hash of a corresponding part of the first verification data.

In a further aspect of the present disclosure, there is provided a provisioning system configured to perform the above described method. In a further aspect of the present disclosure, there is provided a software program configured to perform the above described method when executed on a processor of a provisioning system. In a fourth aspect of the present disclosure, there is provided a method for an electronic device to enable a terminal to perform an authentication operation when the electronic device is executing a software program to perform a transaction via the terminal, the method comprising the software program performing the steps of: in response to receiving a communication related to the transaction from the terminal, generating a response that comprises: (a) one or more items of information for use in processing the transaction; (b) a digital signature generated by the software program based on at least one of the one or more items of information; and (c) a digital certificate to facilitate the terminal to verify the digital signature; and providing the response to the terminal; wherein the digital certificate comprises an indicator that is set to indicate that the software program is invalid.

The indicator may be an expiry date for the software program and the indicator has been set to represent an expired expiry date.

The terminal may be arranged, upon detection that the indicator has been set to indicate that the software program is invalid, to either (a) initiate a subsequent authentication process involving an authorisation system with which the terminal is in communication or (b) decline the transaction

In a further aspect of the present disclosure, there is provided an electronic device comprising: a processor; and a memory storing a software program, wherein the software program, when executed by the processor, causes the processor to perform at least part of the method of the above described fourth aspect of the present disclosure.

In a further aspect of the present disclosure, there is provided a software program configured to perform at least part of the method of the above described fourth aspect of the present disclosure when executed on a processor of an electronic device.

In a further aspect of the present disclosure, there is provided a method for enabling an electronic device to enable a terminal to perform an authentication operation when the electronic device is performing a transaction via the terminal, the method comprising a provisioning system performing the steps of: generating the above described software program for use by the electronic device in performing the transaction; generating a digital certificate associated with the software program, wherein the digital certificate comprises an indicator that is set to indicate that the software program is invalid; and outputting the software program and the digital certificate for provision to the electronic device.

In a further aspect of the present disclosure, there is provided a provisioning system configured to perform the above described method. In a further aspect of the present disclosure, there is provided a software program configured to perform the above described method when executed on a processor of a provisioning system.

In a fifth aspect of the present disclosure, there is provided a method for a mobile electronic device to generate and provide an output relating to a financial transaction, the method comprising software that is executing on a processor of the mobile electronic device performing the steps of: at least two parties, implemented in the software, jointly performing multiparty computation to execute a cryptographic process to generate a result; and outputting the output, based at least in part on the result, for provision to a terminal for use in performing the transaction.

Optionally, the cryptographic process comprises a data encryption process.

Optionally, the cryptographic process comprises a keyed hash function for generating a message authentication code.

Optionally, the cryptographic process comprises generating a digital signature.

Optionally, the output is authentication data that is suitable for use by the terminal to perform an authentication operation.

Preferably, the cryptographic process is performed, at least in part, on (a) data relating to the financial transaction and (b) electronic device information, wherein the electronic device information comprises one or both of: (i) information suitable for identifying the mobile electronic device and (ii) information specifying at least part of a configuration of the mobile electronic device.

Optionally, the information suitable for identifying the mobile electronic device is based, at least in part, on at least one of a device MAC address; and/or a device IMEI, and/or wherein the information specifying at least part of a configuration of the mobile electronic device is based, at least in part, on at least one of: the whole or a part of an operating system of the device; a version or type of the mobile electronic device; and/or a mobile operating system application software token provided by a platform application store stored on the mobile electronic device.

Preferably, the cryptographic process uses first secret data that is stored as part of a first party of the at least two parties and second secret data that is stored as part of a second party of the at least two parties.

Preferably, a first party of the at least two parties is programmed in a first programming language; and a second party of the at least two parties is programmed in a second programming language, and wherein; the first programming language is different to the second programming language.

Preferably, the first party is implemented as first obfuscated code based on a first obfuscation methodology.

Preferably, the second party is implemented as second obfuscated code based on a second obfuscation methodology.

Preferably, the first obfuscation methodology is different to the second obfuscation methodology.

Also disclosed is a mobile electronic device comprising: a processor; and a memory storing a software program, wherein the software program, when executed by the processor, causes the processor to perform the method of the fifth aspect of the present disclosure. Also disclosed is a software program configured to perform the method of the fifth aspect of the present disclosure when executed on a processor of a mobile electronic device.

Also disclosed is a method for configuring a mobile electronic device to enable the mobile electronic device to generate and provide an output relating to a financial transaction, the method comprising the step of: providing the above described software to the mobile electronic device.

The method may further comprise a step of generating the above described software.

Also disclosed is a provisioning system configured to perform the above method.

There is also described a method for performing a cryptographic process to generate a result, the method comprising the steps of: at least two parties, implemented in software, jointly performing multiparty computation to generate the result, wherein; a first party of the at least two parties is programmed in a first programming language; and a second party of the at least two parties is programmed in a second programming language, and wherein; the first programming language is different to the second programming language.

Preferably, the first party is implemented as first obfuscated code based on a first obfuscation methodology.

Preferably, the second party is implemented as second obfuscation code based on a second obfuscation methodology.

Preferably, the first obfuscation methodology is different to the second obfuscation methodology.

Optionally, the cryptographic process uses first secret data that is stored as part of a first party of the at least two parties and second secret data that is stored as part of a second party of the at least two parties.

Optionally, the cryptographic comprises a data encryption process. Optionally, the cryptographic process comprises a keyed hash function for generating a message authentication code.

Optionally, the cryptographic process comprises generating a digital signature.

Optionally, the result is authentication data that is suitable for use in authenticating a transaction.

Optionally, the result is suitable for generation of authentication data for use in

authenticating a transaction, for example a financial transaction.

Optionally, the cryptographic process comprises a decryption process.

Optionally, the cryptographic process is performed, at least in part, on (a) data relating to the transaction and (b) electronic device information, wherein the electronic device information comprises one or both of: (i) information suitable for identifying an electronic device and (ii) information specifying at least part of a configuration of the electronic device.

The information suitable for identifying the mobile electronic device may be based, at least in part, on at least one of a device MAC address; and/or a device IMEI, and/or wherein the information specifying at least part of a configuration of the mobile electronic device is based, at least in part, on at least one of: the whole or a part of an operating system of the device; a version or type of the mobile electronic device; and/or a mobile operating system application software token provided by a platform application store stored on the mobile electronic device.

Also described is a computing apparatus comprising: a processor; and a memory storing a software program, wherein the software program, when executed by the processor, causes the processor to perform the above described method.

Optionally, the computing apparatus is a mobile electronic device.

Optionally, the computing apparatus is a server. Also described is a software program configured to perform the above described method when executed on a processor of a computing apparatus.

The present disclosure also provides a method for creating a system for performing a cryptographic process to generate a result, the method comprising: creating a first party in software using a first programming language; and creating a second party in software using a second programming language; wherein the at least two parties are configured to jointly perform multiparty computation to generate the result. Preferably the method further comprises a step of obfuscating the first party using a first obfuscation methodology.

Preferably, the method further comprises a step of obfuscating the second party using a second obfuscation methodology.

Preferably, the first obfuscation methodology is different to the second obfuscation methodology.

Also described is a system for performing a cryptographic process to generate a result, the system comprising: at least two parties, implemented in software, jointly performing multiparty computation to generate the result, wherein; a first party of the at least two parties is programmed in a first programming language; and a second party of the at least two parties is programmed in a second programming language, and wherein; the first programming language is different to the second programming language.

Brief description of the drawings

The present invention is described herein, by way of example only, with reference to the following drawings in which:

Figure 1 shows a representation of a virtual card NFC payment system;

Figure 2 is a flowchart illustrating a method for handling a transaction in the virtual card NFC payment system of Figure 1 ; Figure 3 is a flowchart illustrating a method by which authentication data may be generated for use in the method of Figure 2;

Figure 4 is a flowchart illustrating a further method by which authentication data may be generated for use in the method of Figure 2;

Figure 5 is a flowchart illustrating a method for provisioning transaction software to a mobile electronic device; Figure 6 is a flowchart illustrating an example of how to process a transaction when a point of sale is operating in an off-line context, according to an embodiment of the invention; and

Figure 7 is a software system comprising a first party and a second party configured to jointly perform multi party computation (MPC).

Detailed description

Figure 1 shows a representation of a virtual card NFC payment system according to an embodiment of the invention. The system comprises a mobile electronic device 100, a point of sale (POS) 160 and a host system 170.

The electronic device 100 comprises a processor (not shown in figure 1 ) that is arranged to execute virtual card payment software 1 10 (referred to herein as transaction software 1 10) that is stored in a memory of the mobile electronic device 100. The virtual card payment software is for providing a virtual payment product (for example a virtual credit card or a virtual debit card or a virtual merchant/store card) - the virtual payment product is to enable payment transactions to be carried out using the electronic device 100. The processor is also arranged to execute an operating system (OS) 120, and may execute any other software 1 15 that may be stored in the memory of the electronic device 100.

The electronic device 100 also comprises an NFC controller 130 and an NFC input/output element 140 (such as an aerial for NFC communications). NFC and protocols for performing NFC are well-known in this field of technology and shall not be described in detail herein. The NFC controller 130 is responsible for performing the NFC functionality at the electronic device 100 and for using the NFC input/output element 140 to communicate, via NFC, with another NFC-enabled device (such as the POS 160, as discussed below).

The electronic device 100 may also comprise a (potentially removable) secure element (SE) 150, for example a subscriber identity module (SIM) 150, although it will be

appreciated that embodiments of the invention do not require the SE 150.

The electronic device 100 is "mobile" in the sense that a user can carry or move it to the POS 160 in order to be able to carry out a transaction via the POS 160. The electronic device 100 may be, for example, a mobile telephone, a personal digital assistant, a tablet computer, a laptop, etc.

The POS 160 may be any point of sale or terminal, for example, a point of sale located at a shop, a merchant retail outlet, a train station, an airport, a fuel station, etc. The POS 160 may be any terminal capable of accepting NFC transactions from the electronic device 100, for example a second NFC enabled electronic device (such as a mobile telephone, a personal digital assistant, a tablet computer, a laptop), or a terminal that is attached to and in communication with a second electronic device, for example a mobile telephone, a personal digital assistant, a tablet computer, a laptop, etc., (for example an NFC terminal in a taxi that is attached to and in communication with a second electronic device, such as the driver's mobile telephone etc). As POSs are well-known in this field of technology, they shall not be described in more detail herein except as necessary to understand

embodiments of the invention. The electronic device 100 and the POS 160 are configured to communicate wirelessly with each other using suitable NFC radio frequency (RF) protocols when the NFC input/output element 140 and the POS 160 are within range of each other.

The POS 160 may communicate with the host system 170 by any suitable communications means, such as via one or more networks (such as the internet, a metropolitan area network, a local area network, a telecommunications network, a satellite network, etc.) and the communications may comprise wired and/or wireless communications.

The host system 170 may be operated, for example, by the provider of, or operator associated with, the virtual payment product being provided by the transaction software 1 10, and/or by a third party that may be associated with such a provider or operator. For example, the host system 170 may be operated by a bank or a building society. The host system 170 may be configured to carry out a number of different tasks relating to transaction execution, including authorisation of transactions and actually providing the electronic device 100 with the transaction software 1 10 in the first place. Thus, the host system 170 may be viewed as comprising an authorisation (or authentication) system 171 for authorising a transaction and a provisioning system 172 for providing the transaction software 1 10 to the electronic device 100. The authorisation system 171 and the provisioning system 172 may be operated by different entities (and may, therefore, be separate systems) or may be operated by the same entity (and may, therefore, be separate systems or a combined system). The authorisation system 171 and the provisioning system 172 may each comprise one or more servers that may be arranged to carry out one or more operations as discussed below. The electronic device 100 may also be arranged to communicate with the host system 170 by any suitable communications means, such as via one or more networks (such as the internet, a metropolitan area network, a local area network, a telecommunications network, a satellite network, etc.). Such communications may occur during a software provisioning process (described in more detail later). However, a data connection directly (i.e. not via the POS 160) between the electronic device 100 and the host system 170 when performing a transaction is not necessary.

The electronic device 100 is arranged so that the transaction software 1 10 may access and use, or hook into, the NFC controller 130 via the OS 120, without any involvement of the SE 150. Thus, the transaction software 1 10 may emulate an SE. The transaction software 1 10 may send commands and/or data to the NFC controller 130 and receive and process commands and/or data sent to the NFC controller 130 from the POS 160. Thus, NFC transactions may be performed on the client side (i.e. on the electronic device 100 side) by the transaction software 1 10, without any need for, or recourse to, the SE 150. Thus, the SE 150 is shown in Figure 1 only for the purposes of demonstrating a connection that may exist between the NFC controller 130 and an SE 150, since the SE 150 is not required at all for carrying out NFC transactions in embodiments of the invention. Thus, the disadvantages discussed above in using an SE 150 are overcome. When carrying out an NFC transaction, before a transaction is approved or allowed by the authorisation system 1 71 , transaction information is sent to the authorisation system 1 71 (to enable the authorisation system 1 71 to allow/approve/authorise or refuse/decline the transaction) to minimise the risk of actioning fraudulent transactions.

Figure 2 is a flowchart illustrating a method for handling a transaction in the virtual card NFC payment system of Figure 1 . The method illustrated in figure 2 assumes that the electronic device 1 00 is close enough to the POS 1 60 to enable the electronic device 1 00 and the POS 1 60 to communicate with each other via NFC.

In step S210, the POS 160 transmits information relating to the desired payment transaction to the transaction software 1 1 0 (via the NFC controller 1 30 of the electronic device 100). The information relating to the transaction may comprise transaction data defined by an electronic transaction standard, for example the EMV (Europay, MasterCard and Visa) global standards. The information relating to the transaction may comprise at least one of: a transaction amount (authorised), a transaction amount (other), a terminal (POS) country code, transaction currency code, transaction date, transaction type and an unpredictable number. It will be appreciated, however, that the information relating to the transaction may comprise any type of data or information or attribute associated with, or describing, the desired transaction.

In Step S220, the transaction software 1 10 generates authentication data based on the information relating to the transaction that the transaction software 1 1 0 received at Step S210. The generation of this authentication data shall be described in more detail below with reference to Figure 3. This authentication data is data that the authorisation system 171 can use when authenticating the transaction.

As shall be described in more detail later, the authentication data is generated based, at least in part, on (a) the data relating to the transaction received at Step S210 and (b) device information, wherein the device information comprises one or both of: (i) information on the electronic device 1 00 suitable for identifying the electronic device 1 00 and (ii) information specifying at least part of a configuration of the electronic device 1 00.

In Step S230, the transaction software 1 10 outputs authentication information (namely information comprising the generated authentication data, and possibly other data too). The authentication information is passed from the transaction software 1 10 to the NFC controller 1 30 for NFC transmission to the POS 160.

In Step S240, the POS 160 receives the authentication information and transmits an authorisation request to the authorisation system 1 71 via a data connection.

In some embodiments, the authentication information received from the transaction software 1 10 merely contains the authentication data that the transaction software 1 10 generated. In this case, the POS 1 60 may generate the authorisation request so that the authorisation request comprises, or is based on, the authentication data and at least part of the information relating to the transaction that was transmitted to the transaction software 1 1 0. In other embodiments, the authentication information received from the transaction software 1 10 contains the authentication data that the transaction software 1 1 0 generated along with at least part of the information relating to the transaction that was transmitted to the transaction software 1 10. In this case, the POS 160 may generate the authorisation request so that it comprises the authentication information. In either case, as shall be described shortly, the authentication information may comprise further data (in addition to the authentication data and data relating to the transaction). In Step S250, the authorisation system 1 71 receives the authorisation request and performs an authorisation process on the authorisation request. Part of this authorisation process may comprise checking various rules, such as whether a credit limit or overdraft limit associated with the virtual payment product would be exceeded if the transaction were approved (in which case the authorisation system 1 71 would decline the transaction). As part of the authorisation process, the authorisation system performs 171 an authentication process. In particular, the authorisation system 171 performs an authentication process on the data relating to the transaction (which formed part of the authorisation request received at the authorisation system 171 ) using the authentication data (which also formed part of the authorisation request received at the authorisation system 171 ). The authentication process determines whether the information relating to the transaction received in the authorisation request is authentic - in embodiments of the invention, the information relating to the transaction is authentic if (a) the information relating to the transaction has not been modified and (b) the information relating to the transaction was generated by the particular transaction software 1 10 executing on the particular electronic device 100 that the authorisation system 1 71 believes is involved in this transaction. This shall be described in more detail later. If is determined that the information relating to the transaction is not authentic, then the result of the authorisation process is that the transaction is to be declined; if is determined that the information relating to the transaction is authentic, then the result of the authorisation process is that the transaction is to be allowed provided, of course, that each of the other rules (if any) that are checked, as mentioned above, indicate that the transaction is to be allowed.

If it is determined that the transaction is allowed, then in Step S260 the authorisation system 1 71 (or by some other system associated with the authorisation system 171 ) performs transaction processing to give effect to the transaction (as is well-known in this field of technology). In Step S270, the authorisation system 1 71 may send to the POS 160 a confirmation that the transaction has been allowed. The POS 160 may then provide an indication to the user of the electronic device 1 00 that the transaction has been allowed. In Step S280, the POS 160 may transmit a confirmation that the transaction has been allowed to the transaction software 1 1 0. The transaction software 1 10 may then provide an indication to the user of the electronic device 1 00 that the transaction has been allowed.

If, on the other hand, it is determined that the transaction is declined, then in Step S285 the authorisation system 1 71 (or by some other system associated with the authorisation system 1 71 ) performs processing relating to declining the transaction (e.g. logging a declined transaction, as is well-known in this field of technology). In Step S290, the authorisation system 1 71 may send to the POS 160 an indication that the transaction has been declined. The POS 160 may then provide an indication to the user of the electronic device 100 that the transaction has been declined. In Step S292, the POS 160 may transmit an indication to the transaction software 1 1 0 that the transaction has been declined. The transaction software 1 1 0 may then provide an indication to the user of the electronic device 1 00 that the transaction has been declined.

Figure 3 is a flowchart illustrating a method by which authentication data may be generated for use in the method of Figure 2. In particular, Figure 3 is a flowchart illustrating a method by which authentication data may be generated at Step S220 of Figure 2.

The transaction software 1 1 0 generates a first session key (SK1 ) using a first

algorithm/process (CA1 ), which may comprise a cryptographic algorithm/process. SK1 may be generated in any suitable way for generating a session key, as is known in this field of technology. SK1 may be of any suitable data size, but generally related to the cryptographic algorithm in CA1 , for example, 16 to 24 bytes.

In one embodiment, the electronic device 100 stores a counter 310, referred to below as an application transaction counter (ATC) 31 0. ATC 310 is a number that is incremented with every transaction and, therefore, is unique to that transaction. ATC 310 may have any suitable data size, for example 2 bytes, and if the number of transactions reaches the maximum allowable (which may be the data limit of ATC 310, or a lower number fixed during provisioning of the virtual payment product), the virtual payment product may expire and a new virtual payment product may be provisioned to the electronic device 100 (e.g. by updating the transaction software 1 10).

The transaction software 1 1 0 may generate SK1 by providing ATC 310 as an input to CA1 , so that SK1 is generated based, at least in part, on ATC 31 0. In this way, SK1 should be different for every transaction (since each transaction will have a different value for ATC 31 0).

In some embodiments, CA1 is a keyed algorithm, and CA1 uses a cryptographic key as an input to generate SK1 . Therefore, the transaction software 1 10 may have embedded, as part of the transaction software, a cryptographic key, referred to herein as a device key (or DK) 320, which the transaction software 1 10 uses as an input to CA1 in order to generate SK1 . DK 320 may be stored in any manner within the transaction software 1 10 using any appropriate techniques - preferably, DK 320 is stored in a secured manner using any well known cryptographic or security techniques as are well-known in this field of technology. DK 320 may have any suitable data size, but generally related to the cryptographic algorithm in CA1 , for example it may be between 1 6 to 24 bytes. DK 320 may be configured by the provisioning system 1 72 to be unique to the electronic device 100 (as described later). DK 320 may be managed and/or updated (for example, if it expires) on a periodic basis by the provisioning system 1 72.

It will be appreciated that CA1 may receive, and process, additional data as its input to generate SK1 .

As the transaction software 1 1 0 uses SK1 to generate the authentication data, the authentication data is generated based, at least in part, on ATC 31 0. Having generated SK1 , an authentication request cryptogram (ARQC) 360 is generated using a second algorithm/process CA2, which may comprise a cryptographic

algorithm/process. To generate ARQC 360, CA2 uses as an input (a) the data relating to the transaction 340 received by the transaction software 1 10 at Step S210 and (b) device information 350, wherein the device information 350 comprises one or both of: (i) information on the electronic device 1 00 suitable for identifying the electronic device 1 00 and (ii) information specifying at least part of a configuration of the electronic device 1 00. To generate ARQC 360, CA2 may also use as an input internal card data 330. In some embodiments, CA2 is a keyed algorithm, and CA2 then uses a cryptographic key, namely SK1 , as an input for generating ARQC 360. It will be appreciated that CA2 may receive, and process, additional data as its input to generate ARQC 360.

The internal card data 330 may comprise information defined in EMV standards, for example at least one of: an identifier of the type of cryptogram returned to the POS 160 (for example, decline, go-online); a flag to indicate whether a PIN was entered or provided; a flag to indicate whether the transaction software 1 10 has communicated with the authorisation system 1 71 ; a flag to indicate whether the ATC 31 0 is at a threshold; a flag to indicate whether transit counters are at a threshold; some reserved flags (which may be set to '0'); and a cryptogram version number (CVN). It will be appreciated that the internal card data 330 may comprise additional, or alternative, data relating to the virtual payment product being provided by the transaction software 1 1 0 (i.e. the virtual payment product to which the transaction is associated). The internal card data 330 used by CA2 may have any suitable data size, for example up to 20 bytes.

The device information 350 may comprise, or be based on (e.g. by calculating a

cryptographic hash), any type of data that is one or both of: (i) information being stored on the electronic device 100 suitable for identifying the electronic device 1 00 and (ii) information specifying at least part of a configuration of the electronic device 1 00. For example, the device information 350 may comprise, or be based on: a device MAC address for the electronic device 100; an International Mobile Station Equipment Identity (IMEI) for the electronic device 100; the whole or a part of the OS 1 20; a version or type or serial number of the electronic device 1 00; an application software token provided by the mobile OS platform application store (e.g. an Android Play Store software token, a Microsoft Windows Marketplace software token, a RIM BlackBerry World software token, an Apple App Store software token etc..) being stored on the electronic device 1 00; etc.. The transaction software 1 10 may gather the device information 350 from the electronic device 100 at the time of generating the ARQC 360 to ensure that the ARQC 360 that is generated is based on the current configuration and identity of the specific electronic device 1 00 that is executing the transaction software 1 10. The device information 350 may have any suitable data size, for example up to 30 bytes.

ARQC 360 may take a form defined in a transaction authentication standard, for example EMV standards, and, as such, may typically have a data size of 8 to 1 6 bytes. However, rather than generating an ARQC, CA2 may alternatively generate any suitable

authentication cryptogram of any suitable size but generally related to the cryptographic algorithm in CA2.

The ARQC 360 may be truncated, or otherwise modified, in order to achieve a target data size.

The authentication data generated at Step 220 of Figure 2 is based on the ARQC 360. The authentication data may be equal to the ARQC 360. As discussed below, the

authentication data may be formed by combining the ARQC 360 with other data.

The authentication information output by the transaction software at Step 230 comprises the authentication data generated as set out above. In embodiments that make use of ATC 31 0 to generate ARQC 360, the authentication information further comprises ATC 310 (so that the ATC 310 can be used during the authentication process at the authorisation system 1 71 ). In embodiments that make use of the internal card data 330 to generate

ARQC 360, the authentication information further comprises the internal card data 330 (so that the internal card data 330 can be used during the authentication process at the authorisation system 1 71 ). As discussed above, in some embodiments, the authentication information output by the transaction software 1 10 further comprises the data relating to the transaction 340.

In embodiments that make use of DK 320 to generate ARQC 360, DK 320 is not included in the authentication information. Instead, as will be discussed shortly, DK 320 (or a value based on DK 320) is retrieved or derived by the authorisation system 171 during the authentication process in Step S250. In this way, DK 320 may not be obtained by intercepting the authorisation request transmitted in Step S240 and, therefore, is kept secret from third parties. Furthermore, this means that the value of DK 320 used by the transaction software 1 10 to generate the ARQC 360 must match a corresponding value that the authorisation system 171 has stored and has associated with the transaction software 1 10 on the electronic device 100 in order for the authentication process to successfully authenticate the data relating to the transaction. This enables the

authorisation system 1 71 to verify that the authorisation request has originated from the correct transaction software 1 10 operating on the correct electronic device 1 00. Similarly, the device information 350 is not included in the authentication information.

Instead, as will be discussed shortly, the device information 350 (or a value based on the device information 350) is retrieved or derived by the authorisation system 1 71 during the authentication part of the authorisation process in Step S250. In this way, the device information 350 may not be obtained by intercepting the authorisation request transmitted in Step S240 and, therefore, is kept secret from third parties. Furthermore, this means that the value of the device information 350 used by the transaction software 1 10 to generate the ARQC 360 must match a corresponding value that the authorisation system 1 71 has stored and has associated with the transaction software 1 10 on the electronic device 100 in order for the authentication process to successfully authenticate the data relating to the transaction. This again enables the authorisation system 1 71 to verify that the

authorisation request has originated from the correct transaction software 1 10 operating on the correct electronic device 100 tied to the virtual payment product.

In some embodiments, the transaction software 1 10 is arranged to receive a personal- identification-number (PIN), or some other form of personal identification (such as a fingerprint or retinal image) entered or provided by a user of the electronic device 1 10. In the following, the term PIN shall be used to refer to a personal-identification-number or other value/data (such as fingerprint data or retinal image data) for identifying the user of the electronic device 1 1 0. In such embodiments, the transaction software 1 1 0 is arranged to generate PIN authentication data based, at least in part, on the PIN provided by the user. The authentication information output at Step 230 of Figure 2 may then be based, at least in part, on the PIN authentication data. Examples of this are discussed below.

In some embodiments, the transaction software is arranged to detect, based on the received data relating to the transaction, whether the transaction satisfies a predetermined criterion. The receiving/obtaining of a PIN and generation of PIN authentication data may then be performed only if it is determined that the transaction satisfies the predetermined criterion. As an example, the predetermined criterion may be that a transaction value for the transaction exceeds a predetermined threshold (i.e. this is a "high value" transaction) and/or that the data relating to the transaction requires or specifies that a PIN is received from the user. It will be appreciated that other types of criterion could be used in addition or alternatively. Alternatively, the transaction software 1 1 0 may be configured to support the ability to require a PIN for every transaction, or to require a PIN at predetermined intervals, for example after a certain number of transactions, after the transactions amounts reach a certain cumulative total, etc..

If the transaction software determines that a PIN is required, then, in additional to the steps mentioned above with reference to Figure 3, the transaction software 1 10 also undertakes the 'PIN transaction' steps shown in the dashed-line box 305 in Figure 3. If it is determined that a PIN is required the transaction software 1 10 may ask the user to enter their PIN, or, if the user has already entered their PIN (for example, because the transaction software is configured to enable the user to enter their PIN at the start of transactions), to use the already entered PIN. In particular, in the 'PIN transaction' steps shown in the dashed line box 305 in Figure 3, the transaction software 1 10 may generate a second session key (SK2) using a third algorithm/process (CA3), which may comprise a cryptographic algorithm. In some embodiments, CA3 is a keyed algorithm, and CA3 then uses SK1 as a cryptographic key as an input for generating SK2. The transaction software 1 10 may have embedded, as part of the transaction software 1 10, an initialisation vector 370 (or predetermined constant data value) which the transaction software 1 10 uses as an input to CA3 in order to generate SK2. The initialisation vector 370 may be stored in any manner within the transaction software 1 10 using any appropriate techniques - preferably, the initialisation vector 370 is stored in a secured manner using any well known cryptographic or security techniques as are well-known in this field of technology. The initialisation vector 370 may have any suitable data size, for example it may be between 1 6 to 24 bytes. The initialisation vector 370 may be configured by the provisioning system 1 72 to be unique to the electronic device 100 (as described later). The initialisation vector 370 may be managed and/or updated (for example, if it expires) on a periodic basis by the provisioning system 1 72. SK2 may have any suitable data size, but generally related to the cryptographic algorithm in CA3, for example 16 to 24 bytes. Having generated SK2, PIN authentication data 390 may be generated using a fourth algorithm/process (CA4), which may comprise a cryptographic algorithm. In some embodiments, CA4 is a keyed algorithm, and CA4 then uses SK2 as a cryptographic key as an input for generating the PIN authentication data 390. CA4 uses, as an input, a PIN 380 entered or provided by the user.

The user entered PIN 380 may be of any length, for example it may be four digits, five digits or six digits long. The user entered PIN 380 may have any suitable data size, for example 8 bytes. The PIN authentication data 390 may be of any suitable data size, but generally related to the cryptographic algorithm in CA4, for example 4 to 16 bytes.

The PIN authentication data 390 may be included as part of the authentication information. In particular, the authentication data may be generated based on the PIN authentication data, for example by combining the ARQC 360 with the PIN authentication data. This may be done, for example, by concatenating at least part of the ARQC 360 and at least part of the PIN authentication data 390. Alternatively, it may be necessary according to transaction standards, such as the EMV global standards, for the authentication data to have the same data size regardless of whether or not the PIN transaction steps are performed. Therefore, in some embodiments, the PIN authentication data 390 may be used to modify the ARQC 360, for example by replacing at least some (e.g. a number of bits or bytes) of the ARQC 360 with a corresponding amount of the PIN authentication data 390, or by performing an operation on the ARQC 360 using the PIN authentication data 390, for example by XORing at least part of the ARQC 360 with at least part of the PIN authentication data 390. In this way, the authentication data may always have the same length, being either the ARQC 360 or a modified version of the ARQC 360 (modified using the PIN authentication data 390).

The initialisation vector 370 and the user entered PIN 380 do not form part of the authentication information that is transmitted to the authorisation system 171 as part of the authorisation request. The authorisation system 1 71 may again retrieve or derive each of these values during the authentication process in Step S250 and, thus, they may be kept secure by the electronic device 100 and the authorisation system 171 and not be intercepted by third parties during any data transmissions.

Each of the algorithms CA1 , CA2, CA3 and CA4 may use any suitable method, for example one or more of: The Data Encryption Standard (DES); Triple-DES (3DES); the Advanced Encryption Standard (AES); The Rivest-Shamir-Adleman (RSA) algorithm; elliptic-curve- cryptography (ECC); an XOR; the secure-hashing-algorithm (SHA256); etc. When cryptographic algorithms are used, the algorithms may perform symmetric and/or asymmetric cryptographic operations (such as encryption, decryption, digital signature generation, message authentication code generation, keyed hashing, etc.). All of CA1 , CA2, CA3 and CA4 may use the same underlying method, or some or all of CA1 , CA2, CA3 and CA4 may use different underlying methods. By way of example:

• CA1 may use 3DES or another encryption algorithm to encrypt ATC 31 0 using DK 320 as the encryption key to generate SK1 . Alternatively, CA1 may use a keyed hashing algorithm to generate SK1 as a hash of ATC 31 0, using the key DK 320.

Alternatively, CA1 may combine (e.g. XOR or concatenate) some or all of DK 320 with some or all of ATC 310 to generate SK1 .

• CA2 may generate the ARQC 360 as a (hashed) message authentication code (MAC), e.g. using SHA256, based, at least in part, on the data relating to the transaction 340 and the device information 350 (using SK1 as a key) or may generate a digital signature for the data relating to the transaction 340 and the device information 350 using an asymmetric signature algorithm. The ARQC 360 may be the whole, or a part, of the message authentication code or the digital signature generated.

· CA3 may use 3DES or another encryption algorithm to encrypt the initialisation vector 370 using SK1 as the encryption key to generate SK2. Alternatively, CA3 may use a keyed hashing algorithm to generate SK2 as a hash of the initialisation vector 370, using the key SK1 . Alternatively, CA3 may combine (e.g. XOR or concatenate) some or all of SK1 with some or all of the initialisation vector 370 to generate SK2.

• CA4 may generate the PIN authentication data 390 as a (hashed) message

authentication code (MAC), e.g. using SHA256, based, at least in part, on the PIN 380, or may generate a digital signature for the PIN 380 using an asymmetric signature algorithm. The PIN authentication data 390 may be the whole, or a part, of the message authentication code or the digital signature generated. It will be appreciated that, in some embodiments, the PIN transaction steps are not carried out or provided. When they are provided, the generation of SK2 using CA3 is optional - for example, instead of generating SK2, SK1 may be used in place of SK2, in which case the initialisation vector 370 is not needed and CA3 is not performed.

It will be appreciated that, in some embodiments, CA2 need not use SK1 , in which case CA1 is not performed and ATC 31 0 and DK 320 are not needed. When CA2 uses SK1 , it will be appreciated that CA1 may not be performed and, instead, either (a) SK1 assumes the value of ATC 310 (in which case DK 320 is not needed) or (b) SK1 assumes the value of DK 320 (in which case ATC 310 is not needed).

Figure 4 is a flowchart illustrating an example alternative method by which authentication data may be generated for use in the method of Figure 2. In particular, Figure 4 is a flowchart illustrating a method by which authentication data may be generated at Step S220 of Figure 2 and is an example alternative method to that shown in Figure 3.

The methods shown in Figures 3 and 4 have a number of similarities, for example they both use a number of the same input parameters, for example the ATC 31 0, DK 320 etc, and both can generate an ARQC and optionally PIN authentication data.

In the method shown in Figure 4, the transaction software generates a hash using a fifth algorithm/process (CA5), which may comprise a cryptographic algorithm/process. The hash may be generated in any suitable way known in this field of technology. The hash may be of any suitable data size, for example, 12 to 24 bytes.

The hash may be generated based on the ATC 310, data relating to the transaction 340, the device information 350, an identifier of the virtual payment product 410 and a cryptographic version number (CVN) 420. Further details regarding the ATC 31 0, data relating to the transaction 340 and the device information 350 are described above.

CA5 may concatenate at least part of each of these five inputs (for example, the entirety of each of the inputs may be concatenated, or only a part of some of the inputs and the entirety of the other inputs may be concatenated, or only a part of each of the inputs may be concatenated, etc) and generate the hash based on the concatenation. Alternatively, CA5 may not concatenate the inputs in order to generate the hash, but may instead generate the hash by any other suitable means, for example by XORing the inputs, or hashing each of the inputs and concatenating at least part of the results, etc. As will be appreciated, the identifier of the virtual payment product 410 and the CVN 420 may be part of the internal card data 330 described earlier. Therefore, in an alternative, the identifier of the virtual payment product 41 0 and the CVN 420 shown in Figure 4 may be replaced with internal card data 330, which may comprise the CVN, the identifier of the virtual payment product and any one or more additional data items described earlier in respect of the internal card data 330.

The identifier of the virtual payment product 410 and CVN 420 may each have any suitable data size, for example between 2 and 20 bytes. It will be appreciated that CA5 may receive, and process, additional data as inputs to generate the hash.

As the transaction software 1 1 0 uses the hash to generate the authentication data, the authentication data is generated based, at least in part, on the ATC 31 0, data relating to the transaction 340, the device information 350, an identifier of the virtual payment product 41 0 and the cryptographic version number (CVN) 420.

Having generated the hash, an authentication request cryptogram (ARQC) 430 is generated using a sixth algorithm/process CA6, which may comprise a cryptographic algorithm/process. The transaction software 1 1 0 may generate the ARQC 430 by providing the hash as an input to CA6, so that ARQC 430 is generated based, at least in part, on, the hash, and by extension, therefore, the ATC 310, data relating to the transaction 340, the device information 350, an identifier of the virtual payment product 410 and the cryptographic version number (CVN) 420.

In some embodiments, CA6 is a keyed algorithm, and CA6 uses a cryptographic key as an input to generate ARQC 430. The cryptographic key used in the embodiment shown in Figure 4 is the device key (or DK) 320 that is described in more detail earlier. ARQC 430 may take a form defined in a transaction authentication standard, for example EMV standards, and, as such, may typically have a data size of 8 to 1 6 bytes. However, rather than generating an ARQC, CA6 may alternatively generate any suitable

authentication cryptogram of any suitable size but generally related to the cryptographic algorithm in CA6.

The ARQC 430 may be truncated, or otherwise modified, in order to achieve a target data size. Where the method shown in Figure 4 is implemented, rather than the method shown in Figure 3, the authentication data generated at Step S220 of Figure 2 is based on the ARQC 430. The authentication data may be equal to the ARQC 430. As discussed below, the authentication data may be formed by combining the ARQC 430 with other data. The authentication information output by the transaction software at Step S230 comprises the authentication data generated as set out above. In embodiments that make use of the ATC 31 0 to generate ARQC 430, the authentication information further comprises ATC 310 (so that the ATC 31 0 can be used during the authentication process at the authorisation system 1 71 ). In embodiments that make use of the internal card data 330 (for example, at least the identifier of the virtual payment product 410 and CVN 420) to generate ARQC

430, the authentication information further comprises the relevant internal card data 330 (so that the internal card data 330 can be used during the authentication process at the authorisation system 1 71 ). As discussed above, in some embodiments, the authentication information output by the transaction software 1 10 further comprises the data relating to the transaction 340.

In embodiments that make use of DK 320 to generate ARQC 430, DK 320 is not included in the authentication information. Instead, as will be discussed shortly, DK 320 (or a value based on DK 320) is retrieved or derived by the authorisation system 171 during the authentication process in Step S250. In this way, DK 320 may not be obtained by intercepting the authorisation request transmitted in Step S240 and, therefore, is kept secret from third parties. Furthermore, this means that the value of DK 320 used by the transaction software 1 10 to generate the ARQC 430 must match a corresponding value that the authorisation system 171 has stored and has associated with the transaction software 1 10 on the electronic device 100 in order for the authentication process to successfully authenticate the data relating to the transaction. This enables the

authorisation system 1 71 to verify that the authorisation request has originated from the correct transaction software 1 10 operating on the correct electronic device 1 00. Similarly, the device information 350 is not included in the authentication information. Instead, as will be discussed shortly, the device information 350 (or a value based on the device information 350) is retrieved or derived by the authorisation system 1 71 during the authentication part of the authorisation process in Step S250. In this way, the device information 350 may not be obtained by intercepting the authorisation request transmitted in Step S240 and, therefore, is kept secret from third parties. Furthermore, this means that the value of the device information 350 used by the transaction software 1 10 to generate the ARQC 430 must match a corresponding value that the authorisation system 1 71 has stored and has associated with the transaction software 1 10 on the electronic device 100 in order for the authentication process to successfully authenticate the data relating to the transaction. This again enables the authorisation system 1 71 to verify that the

authorisation request has originated from the correct transaction software 1 10 operating on the correct electronic device 100 tied to the virtual payment product.

If the transaction software 1 1 0 determines that a PIN is required for a transaction (by virtue of one or more of the determination/criteria described earlier in respect of the method shown in Figure 3), then, in addition to the steps mentioned above with reference to Figure 4, the transaction software also undertakes the 'PIN transaction' steps shown in the dashed-line box 405 in Figure 4. If it is determined that a PIN is required, the transaction software 1 10 may ask the user to enter their PIN, or, if the user has already entered their PIN (for example, because the transaction software is configured to enable the user to enter their PIN at the start of transactions), to use the already entered PIN.

In particular, in the 'PIN transaction' steps shown in the dashed line box 405 in Figure 4, the transaction software 1 10 may generate PIN authentication 440 using a seventh algorithm/process (CA7), which may comprise a cryptographic algorithm. In some embodiments, CA7 is a hash algorithm that generates the PIN authentication data 390 by hashing at least part of the ARQC 430 and the user entered PIN 380 (the user entered PIN 380 is described in more detail above in respect of Figure 3). For example, CA7 may concatenate at least part of the ARQC 430 and the user entered PIN 380 (for example, the entirety of each of the inputs may be concatenated, or only a part of some of the inputs and the entirety of the other inputs may be concatenated, or only a part of each of the inputs may be concatenated, etc) and generate the hash based on the concatenation.

Alternatively, CA7 may not concatenate the inputs in order to generate a hash, but may instead generate the PIN authentication data 440 by any other suitable means, for example by XORing the inputs, or using a keyed algorithm or hashing each of the inputs and concatenating at least part of the results, etc.

The PIN authentication data 440 may be of any suitable data size, but generally related to the cryptographic algorithm CA7, for example 4 to 32 bytes.

The PIN authentication data 440 may be included as part of the authentication information. In particular, the authentication data may be generated based on the PIN authentication data 440, for example by combining the ARQC 430 with the PIN authentication data 440. This may be done, for example, by concatenating at least part of the ARQC 430 and at least part of the PIN authentication data 440. Alternatively, it may be necessary according to transaction standards, such as the EMV global standards, for the authentication data to have the same data size regardless of whether or not the PIN transaction steps are performed. Therefore, in some embodiments, the PIN authentication data 440 may be used to modify the ARQC 430, for example by replacing at least some (e.g. a number of bits or bytes) of the ARQC 430 with a corresponding amount of the PIN authentication data

440, or by performing an operation on the ARQC 430 using the PIN authentication data 440, for example by XORing at least part of the ARQC 430 with at least part of the PIN authentication data 440. In this way, the authentication data may always have the same length, being either the ARQC 430 or a modified version of the ARQC 430 (modified using the PIN authentication data 440).

The user entered PIN 380 does not form part of the authentication information that is transmitted to the authorisation system 1 71 as part of the authorisation request. The authorisation system 1 71 may again retrieve or derive each of these values during the authentication process in Step S250 and, thus, they may be kept secure by the electronic device 100 and the authorisation system 171 and not be intercepted by third parties during any data transmissions.

Each of the algorithms CA5, CA6 and CA7 may use any suitable method, for example one or more of: The Data Encryption Standard (DES); Triple-DES (3DES); the Advanced Encryption Standard (AES); The Rivest-Shamir-Adleman (RSA) algorithm; elliptic-curve- cryptography (ECC); an XOR; the secure-hashing-algorithm (SHA1 , SHA256 etc); etc. When cryptographic algorithms are used, the algorithms may perform symmetric and/or asymmetric cryptographic operations (such as encryption, decryption, digital signature generation, message authentication code generation, keyed hashing, etc.). All of CA5, CA6 and CA7 may use the same underlying method, or some or all of CA5, CA6 and CA7 may use different underlying methods. By way of example:

• CA5 may generate the hash using, for example, SHA-1 , based, at least in part, on the ATC 310, data relating to the transaction 340, the device information 350, the identifier of the virtual payment product 41 0 and the cryptographic version number

(CVN) 420. Alternatively, CA5 may combine (e.g., XOR) some or all of the ATC 31 0, data relating to the transaction 340, the device information 350, the identifier of the virtual payment product 41 0 and the cryptographic version number (CVN) 420 to generate the ARQC 430.

· CA6 may use Elliptic Curve Cryptography (ECC) or another encryption algorithm to encrypt the hash using DK 320 as the encryption key to generate ARQC 430.

Alternatively, CA6 may use a keyed hashing algorithm to generate ARQC 430 as a hash of the hash generated by CA5, using the key DK 320. Alternatively, CA5 may combine (e.g. XOR or concatenate) some or all of DK 320 with some or all of the hash to generate the ARQC 430.

• CA7 may generate the PIN authentication data 440 as a (hashed) message

authentication code (MAC), e.g. using SHA256, based, at least in part, on the PIN 380, or may generate a digital signature for the PIN 380 using an asymmetric signature algorithm. The PIN authentication data may be the whole, or a part, of the message authentication code or the digital signature generated.

In Step S250, the authorisation system 1 71 carries out the authentication process. The authentication process needs to use processing/operations that correspond to the operations used to generate the authentication data at Step 220. This may be

predetermined at the authorisation system 1 71 (e.g. if only one algorithm is ever used).

However, in some embodiments of the invention, the authorisation system 171 may be able to carry out a number of different authentication processes, in which case the authorisation system 1 71 may be arranged to determine the cryptographic 'recipe' used to generate the authentication data from information included with the authorisation request. For example, the authentication information received as part of the authorisation request may comprise an indication that the authentication data was generated using transaction software 1 10 on the electronic device 100, in which case the authorisation system 171 may use this to determine which authentication process to perform (or how to perform the authentication process) - namely, an authorisation process that corresponds to the method that the transaction software 1 10 used to generate the authentication data. This indication may identify the actual process by which the authentication data was generated by the transaction software 1 10 on the electronic device 100 - this indication could be, for example, the CVN in the internal card data 330. The authorisation request received by the authorisation system 171 identifies the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) involved in the transaction. As shall be described shortly, when the transaction software 1 10 was provisioned to the electronic device 100, the provisioning system 172 will have stored various data relating to the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) in a database, where this database is accessible by the authorisation system 171 . Other information, such as a user's PIN, may be stored in the same, or a different database. The various information stored in the database(s) may be indexed based on the identity of the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100), e.g. a virtual card number. Therefore, having received the authorisation request, the authorisation system 171 can access the data in the database(s) that corresponds to the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100). The required data may be obtained by the authorisation system 171 by looking the data up in a database on, or accessible by, the authentication process of the authorisation system 171 and/or deriving the data from information that is accessible to the authentication process of the authorisation system 171 (which may be stored on the authorisation system 171 or elsewhere).

The authorisation system 171 is able to access, from the database(s), a value or data to be used as (or from which to obtain) device information 350 for use in the authentication process. In this context, this device information may be referred to as authentication process data. This accessed value is stored in a record that corresponds to the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) that the authorisation system 171 believes is involved in the transaction, i.e. the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) identified in the authorisation request.

In embodiments that use DK 320, the authorisation system 171 is able to access, from the database(s), a value or data to be used as (or from which to obtain) a device key DK 320 for use in the authentication process. This accessed value is stored in a record that corresponds to the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) that the authorisation system 171 believes is involved in the transaction, i.e. the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) identified in the authorisation request.

In embodiments that use the initialisation vector 370, the authorisation system 171 is able to access, from the database(s), a value or data to be used as (or from which to obtain) an initialisation vector 370 for use in the authentication process. This accessed value is stored in a record that corresponds to the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) that the authorisation system 171 believes is involved in the transaction, i.e. the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) identified in the authorisation request.

In embodiments that use the PIN 380, the authorisation system 171 is able to access, from the database(s), a value or data to be used as (or from which to obtain) a PIN 380 for use in the authentication process. This accessed value is stored in a record that corresponds to the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) that the authorisation system 171 believes is involved in the transaction, i.e. the virtual payment product (or that particular transaction software 1 10 executing on that particular electronic device 100) identified in the authorisation request. The authorisation system 171 has access to data relating to the transaction 340 (as this is part of the authentication information in the authorisation request). Additionally, in embodiments that make use of ATC 310, the authorisation system 171 has access to ATC 310 (as this is part of the authentication information in the authorisation request). Similarly, in embodiments that make use of the internal card data 330 (or specifically the identifier of the virtual payment product 410 and/or CVN 420), the authorisation system 171 has access to internal card data 330 (or the identifier of the virtual payment product 410 and/or CVN 420) (as this is part of the authentication information in the authorisation request).

Thus, the authorisation system 1 71 has access to input data values for all of the operands (or inputs to the algorithms CA1 , CA2, CA3, CA4, CA5, CA6 and CA7) of the methods illustrated in Figures 3 and 4 - some of these values are obtained from the authorisation request; some of the values are obtained from one or more records in one or more databases accessible to the authorisation system 1 71 . The authorisation system 1 71 therefore carries out the process shown in Figure 3 or Figure 4, as described above, using the data received in authentication information and the data obtained from the database(s) in order to generate "test" (or second) authentication data. The authorisation system 1 71 can then compare the test authentication data with the authentication data received in the authorisation request. If the authentication data received in the authorisation request matches the test authentication data (e.g. the authentication data is the same as the test authentication data), then the test authentication data will be a reconstructed version of the authentication data and the authentication will be successful, i.e. the authentication process determines that the information relating to the transaction received in the authorisation request is authentic, and the authorisation process proceeds to Step S260.

If the authentication data received in the authorisation request does not match the test authentication data (e.g. the authentication data is not the same as the test authentication data), then the authentication is unsuccessful, i.e. the authentication process determines that the information relating to the transaction received in the authorisation request is not authentic, and the authorisation process proceeds to Step S285. An unsuccessful authentication may be caused by at least one of: (a) one or more of the non-transmitted data items used to generate the test authentication data not matching that which was used by the software application 1 10 to generate the authentication data (for example, the value of at least one of DK 320, the device information 350, the initialisation vector 370, and PIN

380 used by the host system 1 70 in the authentication process being different from the corresponding value used by the transaction software 1 1 0 to generate the authentication data), which could be due to the authorisation request being corrupted or tampered with, or due to the authorisation request originating from a device or transaction software other than that which the authorisation system 171 believes is involved in the transaction; and/or (b) one or more of the algorithms CA1 , CA2, CA3, CA4, CA5, CA6 or CA7 used by the authorisation system 171 in the authentication process being different from that used by the transaction software 1 10 to generate authentication data; and/or (c) the authentication information being tampered with or modified during transmission between the electronic device 100 and the POS 160 and/or between the POS 160 and the authorisation system 171 . These may indicate fraudulent activity and, therefore, the authorisation system 171 will decline the transaction and proceed to Step S285.

It may be possible to identify what has caused the authentication process to fail, however it may be arranged that this is not communicated to the user of the electronic device 100 in Steps S290 and/or S292, or to any other entity, as this may assist third parties in breaking the authentication process. However, where it is identified that the user entered PIN 380 was incorrect, the owner of the virtual card may be notified by a different communications channel, for example SMS, email or a telephone call, that the entered PIN was incorrect. In this way, if the user of the electronic device 100 is the owner of the virtual card, they may be made aware of their mistake, but if the user of the electronic device 100 is a fraudulent party, they may not be made aware of what caused the transaction failure.

Implementation of the above described processes helps to improve the safety and security of NFC transactions without the use of an SE on the electronic device 100. In particular, the use of the device information 350 in the manner set out above means that only the specific device to which the transaction software 1 10 was initially provisioned should be able to successfully carry out a transaction. The use of DK 320 and the initialisation vector 370 achieve a similar effect and help increase the overall security of the processing and transactions.

Provisioning of at least parts of the software application 1 10 may take place at any time during the life-cycle of a virtual payment product. For example, it may be carried out at the same time that a new virtual payment product is being issued to the user, or when the user chooses to enable NFC transactions, or when a provisioned virtual transaction card has expired, been cancelled or blocked and new transaction software 1 10 needs to be provisioned, or when a new/updated version of the transaction software 1 10 is available.

Figure 5 is a flowchart illustrating a method for provisioning transaction software 1 10 to a mobile electronic device 100 according to an embodiment of the invention. As indicated above, the process may be initiated at any time during the life-cycle of the virtual payment product and may be initiated by either the electronic device 1 00 (for example, when the user chooses to enable NFC transactions) or by the host system 1 70 (for example, when an existing virtual payment product has been blocked).

In Step S51 0, the electronic device 100 transmits to the provisioning system 172 the device information 350 (examples of which have been described above). The device information 350 may be retrieved by an application executing on the electronic device 1 00. The device information 350 may be retrieved from the OS 120 or any other suitable element on the electronic device 1 00 (e.g. a memory storing a MAC address for the electronic device 100 or a memory storing a version or type or serial number of the electronic device 100). The transmission of the device information 350 to the provisioning system 1 72 takes place via a data connection between the electronic device 100 and the host system 170 shown in Figure 1 (examples of which have been discussed above).

Other information may also be included in the data transmitted from the electronic device 100 to the provisioning system 1 72, for example an indication of whether only a part or the whole of the transaction software 1 10 needs to be provisioned - in particular, if the electronic device 1 00 does not already have transaction software installed, then the whole of the transaction software 1 1 0 may be required, whereas if the electronic device 1 00 already has one version of the transaction software installed, then the electronic device 1 00 may only need to receive an update for part of the transaction software 1 10. Furthermore, the data transmitted from the electronic device 100 to the host system 1 70 may also include other information, for example indicating a customer ID, an account ID and/or a product ID. This information may, for example, be added to the transmission by a mobile gateway.

On receipt of the device information 350, in Step S520 the provisioning system 1 72 generates the required at least part of the transaction software 1 1 0. This may involve generating material or data that will be required by the at least part of the transaction software 1 10 to generate authentication data in the future at Step S220. For example: • In embodiments that use DK 320, the provisioning system 172 may generate DK 320 (e.g. as a random number or based, at least in part, on the received device information 350). The generated DK 320 may be specific (or unique) to the electronic device 1 00 (or the transaction software 1 1 0 to be executed on that electronic device 1 00, or the virtual payment product in question). The generated DK 320 may be embedded as part of the at least part of the transaction software 1 1 0 (e.g. as a value stored within the at least part of the transaction software 1 1 0) - preferably, DK 320 is embedded in a secured manner using any well known cryptographic or security techniques as are well-known in this field of technology.

• In embodiments that use the initialisation vector 370, the provisioning system 1 72 may generate the initialisation vector 370 (e.g. as a random number or based, at least in part, on the received device information 350). The generated initialisation vector 370 may be specific (or unique) to the electronic device 1 00 (or the transaction software 1 10 to be executed on that electronic device 100, or the virtual payment product in question). The generated initialisation vector 370 may be embedded as part of the at least part of the transaction software 1 10 (e.g. as a value stored within the at least part of the transaction software 1 1 0) - preferably, the initialisation vector 370 is embedded in a secured manner using any well known cryptographic or security techniques as are well-known in this field of technology.

In Step S530, the device information 350 (and DK 320 and the initialisation vector 370 in embodiments that use DK 320 and the initialisation vector 370) are stored by the provisioning system 1 70 in one or more databases. These values/data are stored as being associated with the at least part of the transaction software 1 1 0 to be provisioned to the electronic device 1 00. For example, a database may store a record for each provisioned at least part of the transaction software 1 1 0, where the record for an at least part of the transaction software 1 10 comprises the device information 350 (and DK 320 and the initialisation vector 370 in embodiments that use DK 320 and the initialisation vector 370) that are embedded within that at least part of the transaction software 1 10. The

database(s) may be local to the provisioning system 172 or local to the authorisation system 1 71 or remote from, but accessible to, the provisioning system 172 and the authorisation system 1 71 . By storing this information with an association to the transaction software 1 10 installed on the electronic device 100, the information is bound to that particular transaction software 1 1 0. Furthermore, as the information stored in the database(s) comprises the device information, the transaction software 1 1 0 and the electronic device 100 are further bound together. Thus, if this particular provisioned at least part of the transaction software 1 1 0 is executed on a different electronic device 1 00, then the authentication process at Step 250 will fail - i.e. the particular transaction software 1 10 provisioned to this particular electronic device 100 can only be successfully executed on this particular electronic device 100, as attempts to use it on a different electronic device 100 will result in authentication failures and, therefore, declined transactions.

In Step S540, the provisioning system 172 transmits or provisions (via the data connection between the electronic device 100 and the provisioning system 172) the generated at least part of the transaction software 1 10 to the electronic device 100 for storage in memory on the electronic device 100.

The above-described embodiments involve the POS 160 operating in a so-called On-line' context or mode. In the On-line' context, the POS 160 forwards an authorisation request to the authorisation system 171 at the time that the user is using the electronic device 100 to perform the transaction. However, in other embodiments, the POS 160 may operate in an Off-line' context or mode such that there is no active communication between the POS 160 and the authorisation system 171 at the time that the transaction is taking place, i.e. at the time that the user is using the electronic device 100 to perform the transaction. When operating in an Off-line' context, the POS 160 does not forward straightaway the

authentication information to the authorisation system 171 for authentication. Instead, the POS 160 may store the authentication information described above and then, at a later stage, forward the stored authentication information to the authorisation system 171 for authentication when the POS 160 is operating in an On-line' context or when the authorisation system 171 can otherwise obtain, or be provided with, the authentication information from the POS 160. The POS 160 may be configured to be permanently Off- line' - for example, the POS 160 may not actually have the capability to communicate with the authorisation system 171 at the time that the user is using the electronic device 100 to perform the transaction (for example if the POS 160 is a stand-alone vending machine). Alternatively, the POS 160 may have the option of operating in, and switching between, the Off-line' mode and the On-line' mode and may be configured, at any point in time, to be operating in one of these two modes.

The transaction software 1 10 may be configured to enable the POS 160 to perform Off-line' authentication. To enable this, during the provisioning process described above and shown in Figure 5, in Step S520 the provisioning system 172 may further generate at least a private key (referred to herein as a device private key) and a corresponding digital certificate (referred to herein as a device digital certificate). The device private key may be associated with the electronic device 100 itself, or it may be associated with the particular transaction software 1 10 that is to be provisioning to the electronic device 100. The device digital certificate will include at least a public key (referred to herein as a device public key) that corresponds to the device private key. The device private key may be embedded as part of the at least part of the transaction software 1 10 that is provisioned to the electronic device 100 (for example, as data stored within the at least part of the transaction software 1 10) - the device private key may be embedded in a secured manner using any well known cryptographic or security techniques that are well-known in this field of technology. Alternatively, the device private key may be provisioned to the electronic device 100 as separate from, but along with, the at least part of the transaction software for secure storage in memory on the electronic device 100. Similarly, the device digital certificate may be embedded as part of the at least part of the transaction software 1 10 that is provisioned to the electronic device 100 (for example, as data stored within the at least part of the transaction software 1 10) - the device digital certificate may be embedded in a secured manner using any well known cryptographic or security techniques that are well-known in this field of technology.

Alternatively, the device digital certificate may be provisioned to the electronic device 100 separate from, but along with, the at least part of the transaction software for secure storage in memory on the electronic device 100. In this way, the device private key may be used by the transaction software 1 10 during an off-line authentication process; and the device digital certificate (once provided by the transaction software 1 10 to the POS 160) may be used by the POS 160 during the off-line authentication process.

The device private key may be used during an off-line authentication process to digitally sign one or more items of information that are transmitted from the transaction software 1 10 to the POS 160 and, if the device digital certificate is provided to the POS 160, then the device public key in the device digital certificate may be used by the POS 160 to authenticate/verify the digital signature (as explained in more detail below).

The generation and use of public keys and private keys using asymmetric cryptographic techniques is well-known in this field of technology. Similarly, digital certificates, digital signatures and methods of generating digital certificates and digital signatures, and methods of authenticating/verifying a digital signature are well-known in this field of technology. Consequently, these concepts shall not be described in more detail herein except where necessary to obtain a better understanding of embodiments of the invention.

In embodiments of the invention, the device digital certificate may also comprise any other information (in addition to the device public key) that may be of use to the POS 160 during an off-line authentication process. For example, the device digital certificate may also comprise one or more details about the virtual payment product provisioned on the transaction software 1 10, such as one or more of a permanent account number (PAN) for the virtual payment product, an expiry date for the virtual payment product and/or an issue date for the virtual payment product. Furthermore, the device digital certificate may also comprise one or more of a expiry date for the device digital certificate, issuer action codes and/or any other data or information that may be of use during off-line authentication.

Issuer action codes indicate, or identify or specify, one or more actions that the provisioning system 172 would like the POS 160 to undertake during off-line authentication. For example, an issuer action code may identify, or comprise, an instruction for the POS 160 that instructs the POS 160, if it is operating in the Off-line' context, to change to the On-line' context so that an on-line authentication process may be executed or to decline the transaction if the POS 160 cannot change to the On-line' context. As another example, an issuer action code may identify, or comprise, an instruction for the POS 160 that instructs the POS 160, if it is operating in the Off-line' context, to allow the POS 160 to perform offline authentication process and to decline the transaction if the off-line authentication process does not result in a successful authentication. Issuer action codes may take any suitable form, for example a form specified by a card issuer.

The device digital certificate may itself be digitally signed using a private key associated with an operator of the provisioning system 172 (referred to herein as a card issuer private key). Consequently, a digital certificate (referred to herein as a card issuer digital certificate) that comprises the public key (referred to herein as a card issuer public key) corresponding to the card issuer private key may be provided to the electronic device 1 10.

The card issuer digital certificate may be embedded as part of the at least part of the transaction software 1 10 that is provisioned to the electronic device 100 (for example, as data stored within the at least part of the transaction software 1 10) - the card issuer digital certificate may be embedded in a secured manner using any well known cryptographic or security techniques that are well-known in this field of technology. Alternatively, the card issuer digital certificate may be provisioned to the electronic device 100 separate from, but along with, the at least part of the transaction software for secure storage in memory on the electronic device 100. In this way, the card issuer digital certificate (once provided by the transaction software 1 10 to the POS 160) may be used by the POS 160 during the off-line authentication process (namely to authenticate and access the device digital certificate). For example, contents of the device digital certificate may have been encrypted using the card issuer private key, in which case the POS 160 may use the card issuer public key (obtained from the card issuer digital certificate) to decrypt the encrypted content of the device digital certificate - in this way, the POS 160 may access or obtain the device public key. It will be appreciated that one or more additional or alternative digital certificates may be provided and used in a similar manner, in line with well-known public-key-infrastructure techniques.

Figure 6 is a flowchart illustrating an example of how to process a transaction when the POS 160 is operating in an off-line context, according to an embodiment of the invention.

In Step S610, the POS 160 transmits to the transaction software 1 10 (via the NFC controller 130 of the electronic device 100) a communication related to the transaction. This step may be analogous to Step S210 of Figure 2, whereby the POS 160 transmits information relating to the desired transaction to the transaction software 1 10 (via the NFC controller 130 of the electronic device 100). In addition to some or all of the information relating to the transaction described in respect of Step S210 above, the information relating to the transaction that is transmitted in the communication at Step S610 may further comprise an indication that the POS 160 is operating in an off-line context.

The transaction software 1 10 may recognise from this received communication (e.g. due to an indication in the received communication) that the POS 160 is operating in an off-line context and that off-line authentication may be undertaken. In Step S620, the transaction software 1 10 may return to the POS 160 (via the NFC controller 130 of the electronic device 100) an indication or identification of an off-line authentication process that the transaction software 1 10 is configured to support. This indication may, for example, be embedded as data or a data structure within the transaction software 1 10 as part of the provisioning process described above and is intended to enable the POS 160 to undertake an authentication process (to authenticate the electronic device 100 and/or the particular transaction software 1 10 being executed) during the off-line transaction.

The indication of the off-line authentication process may, for example, be an application file locator (AFL), using which the POS 160 can look up in its memory, or in a memory or database of a different device to which the POS 160 has access, what items of information will be required from the electronic device 100 in order to process the transaction, and what off-line authentication process should be carried out once the POS 160 has obtained the one or more items of information for use in processing the transaction. For example, the one or more items of information required may comprise the On-line' authentication information (described above in respect of Figures 2, 3 and 4), at least some of the information relating to the transaction (for example, transaction amount etc), any suitable data relating to the virtual payment product that is accessible to the transaction software 1 10, for example the PAN and/or the virtual payment product expiry date etc..

In Step S630, the POS 160 may transmit to the transaction software 1 10 a request for the one or more items of information it has determined it will need for use in processing the transaction. In step S640, the transaction software 1 10 generates and provides to the POS 160 a response to the request.

In Step S650 the POS 160 may undertake off-line transaction authentication and process the transaction based on the response, as discussed in more detail below.

It will be appreciated that the steps S620 and S630 are optional. In particular, the transaction software 1 10 may provide a response to the communication that the POS 160 sent at the step S610, where this response may contain the same information that would be provided if the steps S620, and S630 had been performed.

In either case, the response provided to the POS 160 comprises:

(a) One or more items of information for use in processing the transaction. The one or more items of information may comprise one or more of: information relating to the transaction software 1 10, such as a version of the transaction software 1 10, an expiration date for the transaction software 1 10, etc.;

information relating to a virtual payment product provided by the transaction software 1 10, such as one or more of an account number associated with the virtual payment product, an expiry date for the virtual payment product and/or an issue date for the virtual payment product;

information relating to the transaction (examples of which are discussed above with reference to Figures 2, 3 and 4);

device information 350 (examples of which have been set out above).

(b) A digital signature generated by the transaction software 1 10 at step S640 based on at least one of the one or more items of information. This digital signature is generated using the device private key.

(c) The device digital certificate.

(d) Optionally, one or more further digital certificates (such as the card issuer digital certificate) that the POS 160 may use to access and/or authenticate the device digital certificate (as discussed above).

The off-line transaction authentication process performed by the POS 160 at Step S650 may involve one or more of:

• The POS 160 may use at least some information included in the device digital certificate. For example, where the device digital certificate comprises a certificate expiry date, the POS 160 may check that the device digital certificate is still valid and the off-line transaction authentication process will fail if the certificate is no longer valid. If the device digital certificate comprises virtual payment product information, for example, issue date, expiry date, etc.. the POS 160 may check that all of that information is valid and the off-line transaction authentication process will fail if any of this information is not valid.

• The POS 160 may use the device public key included in the device digital certificate to verify/authenticate the digital signature that was transmitted to the POS 160 in the response at Step S640. This enables the POS 160 to verify the origin and integrity of the one or more items of information that were digitally signed when forming the response. The off-line transaction authentication process will fail if the digital signature is not successfully verified/authenticated.

At least some of the one or more items of information in the response (which may or may not be one or more of the items of information that were digitally signed to form the digital signature) may correspond with some of the information included in the device digital certificate (for example, some of the virtual payment product information in the device digital certificate, such as the PAN, expiry date etc.), in which case the POS 160 may check that these one or more items of information match (e.g. are the same as) the corresponding information in the device digital certificate. This may ensure that that received one or more items of information have not been altered at all since the transaction software 1 10 was provisioned to the electronic device 100. The off-line transaction authentication process will fail any of these one or more items of information do not match (e.g. are not the same as) the corresponding information in the device digital certificate.

If all of these authentication checks are successful, then in Step S560 the authentication is successful and this may recorded by the POS 160. Optionally, after successful

authentication, the method may proceed to Step S570 where the POS 160 may transmit to the electronic device 100 (via NFC) a notification of authentication, such that the

transaction software 1 10 may display that authentication has been successful and the consumer may obtain the goods or services in respect of the desired transaction.

Since the POS 160 is in an off-line mode, the POS 160 may in Step S670 also save all of the necessary transaction related information so that the transaction may be actioned when the POS 160 switches to an On-line' context at a later time. The saved transaction related information may also include the On-line' authentication information that is described in respect of Figures 2, 3 and 4 so that when the POS 160 switches to an On-line' context, an authorisation request as described above with reference to Figures 2, 3 and 4 may be sent to the authorisation system 171 so that the authorisation system 171 may perform its authentication process before the transaction is actually completed by the host system 170. If the On-line' authentication process (which is described above) fails, the financial transaction may be terminated - whilst the consumer may have already left the POS 160 sometime earlier with the purchased good and/or services, the operator of the host system 170 may still be able to take some consequential action, e.g. cancel the virtual payment product for the future and/or notify all POSs to refuse off-line transactions in respect of that virtual payment product etc.

If at least one of the off-line authentication checks are unsuccessful, then at Step S680, the POS 160 may perform an action in accordance with the rules of the POS 160 and/or any issuer action codes that are included in the device digital certificate. For example, if any of the authentication checks fails, the POS 160 may have a rule that the POS 160 must switch to the on-line mode such that on-line authentication may take place, and if it is not possible to switch to the on-line mode, then decline the transaction. The action of the POS 160 may be different depending on which part of the off-line authentication process has failed and the action may be determined by the rules of the POS 160 and/or the issuer action codes.

In Step S680, the POS 160 performs the required action for an unsuccessful

authentication, for example switching to an on-line context for on-line authentication to be performed by the authorisation system 171 , or declining the transaction and optionally sending the transaction software 1 10 (via NFC) notification of a declined transaction.

Where the POS is unable to switch to an on-line context, it may store details of the declined transaction so that when it later switches to an on-line context, the failed authentication can be investigated, for example by the authorisation system 171 , or by any other suitable system, and any necessary action (such as cancelling the virtual payment product) undertaken.

As part of the digital certificate generation in the provisioning process described above, the provisioning system 172 may also generate "verification data" for inclusion in the device digital certificate. The verification data may be based on at least part of the device information 350 (examples of which have been described above) that is transmitted to the provisioning system in 172 in Step S510 of the provisioning process and/or on an indicator that is set to indicate that the transaction software 1 10 is invalid (for example, a software application expiry date that has expired). For example, at least part of the device information 350 may be included as a discrete entry in the device digital certificate and the indicator set to indicate that the transaction software 1 10 is invalid may additionally, or alternatively, be included as a discrete entry in the digital certificate. In addition to this, or as an alternative to this, the verification data may comprise data that is based (or is a function), at least in part, on one or both of the device information and/or the indicator set to indicate that the transaction software 1 10 is invalid. In this case, the data may also be based on any other information or data, for example information relating to the virtual payment product, such as at least one of the PAN, the product expiry date, the product issue date etc.. The verification data may be generated as a hash (e.g. a SHA1 hash) of an amount of data, where this amount of data comprises at least part of the device information 350 and/or the indicator set to indicate that the transaction software 1 10 is invalid, and possibly any other information and data, for example the PAN and virtual payment product expiry date, and the combined data hashed using a hashing algorithm. For example, the amount of data may be a combination (e.g. concatenation or an XOR or some other combination) of least part of the device information 350 and/or the indicator set to indicate that the transaction software 1 10 is invalid, and possibly any other information and data, for example the PAN and virtual payment product expiry date.

By including verification data that is based, at least in part, on at least part of the device information 350, the verification data is bound to the electronic device 100 from which the device information 350 was transmitted in Step S410. By then including the verification data in the device digital certificate, the verification data, and therefore also the electronic device 100 from which the device information 350 was transmitted in Step S410, is bound to the at least part of the transaction software 1 10 to be provisioned to the electronic device 100.

By including verification data that is based, at least in part, on an indicator set to indicate that the transaction software 1 10 is invalid, when the POS 160 comes to consider the indicator during off-line authentication process, the POS 160 can be more certain that the indicator has not been tampered with since the device digital certificate was generated by the provisioning system 172. During the Off-line' authentication process described above, in Step S640, the one or more items of information that form part of the response transmitted to the POS 160 comprise "first verification data". The first verification data may include at least one of device information gathered or generated by the transaction software 1 10 from the electronic device 100 on which the transaction software 1 10 is executing and/or an indicator of the validity of the transaction software 1 10 gathered from the transaction software 1 10. By gathering the device information from the electronic device 1 00 on which the transaction software 1 10 is operating, it may be ensured that the device information that is returned to the POS 1 60 as part of the first verification data is based on the current configuration and identity of the specific electronic device 100 that is executing that specific transaction software 1 10.

During the authentication process in Step S650, the POS 1 60 may additionally authenticate the transaction application 1 10 and/or electronic device 100 by considering the verification data in the device digital certificate and the received first verification data.

For example, if the verification data comprises device information as a discrete entry, the device information received in the first verification data may be directly compared with the verification data in the device digital certificate. If they do not match, the device information sent to the POS 160 as part of the first verification data is different to that used by the provisioning system 1 72 to generate the verification data in the device digital certificate, for example because the transaction software 1 1 0 is now operating on a different electronic device, or because the electronic device 100 has a different configuration now to its configuration during the provisioning process (for example, the electronic device 1 00 has a new or updated OS 120). This may indicate fraudulent activity and, therefore, the POS 1 60 will proceed to Step S680.

If the verification data in the device digital certificate additionally or alternatively comprises data (e.g. a hash) that was based, at least in part, on the device information used during provisioning, the POS 1 60 may generate test data based, at least in part, on the device information included in the received first verification data using a process analogous to that used by the provisioning system 1 72 to generate the verification data in the device digital certificate. In this way, if the information used to generate the test data (i.e. the device information in the received first verification data and any other necessary information) is the same as that used to generate the verification data in the device digital certificate during provisioning, the test data will match the verification data that is in the device digital certificate. If they do not match, at least one of the following may have occurred: (a) the device information in the received first verification data is different to that used by the provisioning system 1 72 to generate the verification data, for example because the transaction software 1 10 is now operating on a different electronic device, or because the electronic device 100 has a different configuration now to its configuration during the provisioning process (for example, the electronic device 100 has a new or updated OS 120); (b) other items in the one or more items of information for use in processing the transaction (for example, the PAN etc) sent to the POS 160 during Step S640 is different to that used by the provisioning system 182 to generate the verification data, for example because the information on the transaction software 1 10 has been modified. These may indicate fraudulent activity and, therefore, the POS 160 will proceed to Step S680.

By basing the verification data in the device digital certificate at least in part on the device information during provisioning, the verification data is bound to the electronic device 100 for which the device digital certificate was generated by the provisioning system 172, the electronic device 100 may be authenticated by the POS 160. Therefore, if the transaction software 1 10 is cloned onto a different electronic device, or onto a payment card, different device information should be sent to the POS 160 during off-line authentication, the new electronic device/payment card will not be authenticated and off-line transactions prevented. Therefore, the use of fraudulent copies of the virtual payment product in off-line transactions may be prevented.

Where the verification data in the device digital certificate is additionally, or alternatively, based on an indicator that is set to indicate that the software program is invalid, the transmitted first verification data described above may additionally or alternatively comprise an indicator of the validity of the software application. An analogous process to that described above in respect of the device information may be carried out in order to verify the indicator of the validity of the software application against the verification data in the device digital certificate.

If the indicator of the validity of the software application received in the first verification data is verified as matching the indicator that is set to indicate that the transaction software is invalid (on which the verification data in the device digital certificate is, at least in part, based), the indicator of the validity of the software application will indicate that the transaction software 1 10 is invalid. Authentication of the transaction software 1 10 will thus fail, since the transaction software 1 10 is invalid. Upon such a failure, the POS 160 will proceed to Step S680 and perform an action in accordance with the POS 160 rules and/or the issuer action codes. As explained above, this action may be to initiate an On-line' authentication process involving the authorisation system 171 (as described earlier in respect of the 'authentication information' and Figures 2, 3 and 4) or decline the transaction (for example, if it is not possible to initiate an on-line authentication and/or authorisation process). This may be a desirable characteristic where payment product issuers do not wish to take the risk of allowing off-line transactions to take place and instead insist that on-line authentication must always be performed. In this way, even if a perfect spoof of the transaction software 1 10 and the electronic device 100 were created on a different electronic device or on a payment card, all transactions may still have to undergo on-line authentication, during which fraudulent activity may be detected with more likelihood than in off-line authentication.

If the indicator of the validity of the software application that is received as part of the first verification data has been altered in any way, for example so as to indicate that the software application is valid (for example, by setting the software application expiry date to a date in the future), the indicator of the validity of the software application will not match the indicator that is set to indicate that the transaction software is invalid (on which the verification data in the device digital certificate is, at least in part, based). This will again cause the authentication of the transaction software 1 10 to fail and the POS 160 will proceed to Step S680 and perform an action in accordance with the POS 160 rules and/or the issuer action codes.

Therefore, it will not be possible to alter the indicator of the validity of the transaction software 1 10 at all on the transaction software 1 10 without off-line authentication still failing, thereby preventing the possibility of off-line authentication succeeding.

Whilst in the above it is explained that the indicator set to indicate that the transaction software 1 10 is invalid may, for example, be an expiry date for the transaction software 1 10 that is set to an expired expiry date (i.e. a date in the past), it may alternatively be any other item of data that could be set to indicate that the transaction software 1 1 0 is invalid, for example a transaction software 1 10 issue date that is set to a date in the future.

By setting the indicator in the device digital certificate to indicate that the virtual payment product is invalid, successful off-line authentication by the POS 160 may be prevented and either an on-line authentication process initiated or the transaction declined. This may be useful where payment product issuers do not wish to take the risk of allowing off-line transactions to take place and instead insist that on-line authentication must always be performed. In this way, even if a perfect spoof of the transaction software 1 10 and the electronic device 1 00 were created on a different electronic device or on a payment card, all transactions may still have to undergo on-line authentication, during which fraudulent activity may be detected with more likelihood than in off-line authentication.

When the provisioning system 1 72 generates the device digital certification with an indicator set to indicate that the transaction software 1 1 0 is invalid, the provisioning system 172 may set the indicator to be any value that would indicate that the transaction software 1 1 0 is invalid. For example, the value could be randomly selected from with the set of possible values that would indicate that the transaction software 1 10 is invalid (e.g. a randomly generated expiration date prior to the current date). The value could be based, at least in part, on the device information 350 received at the provisioning system 350.

In an aspect of the present disclosure, the transaction software 1 1 0 on the electronic device 100 is configured such that at least part of at least one of the cryptographic processes described above, for example generation of the authentication data and/or the digital signature used in off-line transactions, may be performed using multiparty computation (MPC) (also known as Secure Multiparty Computation). Additionally or alternatively, in an aspect of the present disclosure, the POS 1 60 and/or authorisation system 1 71 are configured to perform MPC to carry out at least part of the one or more of their respective cryptographic processes described above, for example the authorisation process carried out by the authorisation system 171 and/or decryption/authentication of the digital signature by the POS 1 60.

MPC is a process whereby a sensitive function, for example a cryptographic process, is split between (or implemented by) two or more different "parties". Herein, each "party" may be an item of software, such as the whole or part of a software application, a software module, a software library, etc. The function implemented by the MPC is "sensitive" in that it makes use of secret data (i.e. data to be hidden from other entities) in order to generate its output. The two or more parties can interact to perform the sensitive function jointly. Each of the two or more parties will have (or store therein) respective secret data, using which they may (together) perform the sensitive function, whilst still keeping their secret data private. For example, any secret data that are required to perform the sensitive function and that are stored in only one of the parties can be utilised to perform the sensitive function and still be kept private/hidden from the other parties. Likewise, other secret data that are required to perform the sensitive function and that are stored in only one of the other parties can also be utilised to perform the sensitive function whilst still keeping the data private. This can improve the security of the implementation of the sensitive function as all of the data required to carry out the sensitive function are not known by any single one of the parties and are not exposed in their entirety at any one location within the memory of the device performing the MPC. Further details regarding the operation of MPC may be found in the paper: Andrew Chi-Chih Yao: Protocols for Secure Computations (extended Abstract) FOCS 1982: 160-164, which may be found at http://research.cs.wisc.edu/areas/sec/yao1 982-ocr.pdf

Figure 7 shows a representation of an embodiment of the transaction software 1 1 0 on the electronic device 1 00. In this embodiment, the transaction software 1 10 is configured to use MPC to perform any one or more of the earlier described cryptographic processes. The transaction software 1 1 0 comprises an optional calling module 710, along with a first party 720 and a second party 730. As with the parties 720, 730, the calling module 71 0 may be an item of software, such as the whole or part of a software application, a software module, a software library, etc. The calling module 710, the first party 720 and the second party 730 are separate items of software within the transaction software 1 10.

When a particular cryptographic process is to be performed (here, the particular cryptographic process is the process being implemented via MPC), the first party 720 and the second party 730 are used to implement and perform the cryptographic process. The particular cryptographic process may be reached as part of the normal execution of the transaction software 1 10; alternatively, performance of the particular cryptographic process may be determined or detected, either by the calling module 710 or any other part of the transaction software 1 10. When the particular cryptographic process is to be performed, the calling module 710 (or some other part of the transaction software 1 10) contacts or calls the first party 720 in step 740 with a request to carry out the cryptographic process, i.e. a request is provided to the first party 720, for example by calling a function of, or using an interface of, the first party 720. The request may comprise, or provide an indication of or a memory address of, data that are required by the first and second parties to carry out the particular cryptographic process. For example, it may comprise data to be encrypted, such as transaction information etc. In step 750, the first party 720 and second party 730 jointly use MPC to perform the cryptographic process and generate a result (for example, the authentication data and/or digital signature), i.e. generate the outcome of the particular cryptographic process when the particular cryptographic process processes specific data to be processed (which may be indicated in the request). In step 760, the first party 720 (additionally or alternatively, the second party 730) returns the result to the calling module 71 0 (although it will be appreciated that the result may be returned to any module or part of the transaction software 1 10). The calling module 71 0, or any other part/module of the transaction software 1 10, may then utilise the returned result in the transaction processes described above in respect of Figure 1 to 6.

The first party 720 may comprise first secret data and the second party 730 may comprise second secret data. Preferably, the first secret data is known only to the first party 720 and is not disclosed at any time to the second party 730 or to any other module or part of the transaction software 1 10, or any other software or application on the electronic device 100 or anywhere else. Preferably, the second secret data is known only to the second party 730 and is not disclosed at any time to the first party 720 or to any other module or part of the transaction software 1 10, or any other software or application on the electronic device 100 or anywhere else. The first party 720 will utilise the first secret data and the second party 730 will utilise the second secret data during step 750 in order to generate the result.

The first and second parties may be configured to perform at least part of the cryptographic process described earlier for the generation of the authentication data. In one example, the first and second parties may be configured to perform CA1 using MPC. Thus, the result returned by the first party 720 in step 760 may be SK1 . By using MPC to generate SK1 , the DK 320 is not stored in its entirety in one location anywhere on the electronic device 100, thus improving the security of the implementation of CA1 and the transaction software 1 1 0. A different module within the transaction software 1 1 0 (which may or may not be the calling module 71 0) may then carry out any other steps necessary to generate the authentication data, which is to be output to a terminal (for example, the POS 160) for authentication of the transaction, as described earlier. For example, the result SK1 may be used to generate the ARQC 360, which may then form at least part of the authentication data that is output to a terminal for authentication of the transaction, as described earlier.

In another example, the first and second parties may be configured to perform CA5 using MPC. Thus, the result returned by the first party 720 in step 760 may be the hash. By using MPC to generate the hash, the data used to generate the hash, for example the ATC 31 0 and/or identifier of the virtual payment product 41 0 etc, may not be stored in their entirety in one location anywhere on the electronic device 1 00, thus improving the security of the implementation of CA5 and the transaction software 1 1 0. A different module within the transaction software 1 10 (which may or may not be the calling module 710) may then carry out any other steps necessary to generate the authentication data, which is to be output to a terminal (for example, the POS 1 60) for authentication of the transaction, as described earlier. For example, the hash may be used to generate the ARQC 430, which may then form at least part of the authentication data that is output to a terminal for authentication of the transaction, as described earlier.

In another example, the first and second parties may be configured to perform CA2 (and possibly CA1 too) using MPC. Thus, the result returned by the first party 720 in step 760 may be the ARQC 360, or the authentication data that is based on the ARQC 360. Again, by utilising MPC in this way, the DK 320 is not stored in its entirety in one location anywhere on the electronic device 1 00, thus improving the security of the implementation of the generation of the ARQC 360 and the security of implementation of the transaction software 1 10. If necessary, a different module within the transaction software 1 1 0 (which may or may not be the calling module 71 0) may then carry out any other steps required to generate the authentication data, which is to be output to a terminal for authentication of the transaction, as described earlier. For example, if the result is the authentication data, it may be that no further steps need to be performed and the authentication data may simply be output to a terminal for authentication of the transaction, or it may be that the authentication data is modified in some way before being output to the terminal, or is included as only part of the output to the terminal.

In another example, the first and second parties may be configured to perform CA6 (and possibly CA5 too) using MPC. Thus, the result returned by the first party 720 in step 760 may be the ARQC 430, or the authentication data that is based on the ARQC 430. By utilising MPC in this way, the DK 320 is not stored in its entirety in one location anywhere on the electronic device 1 00, thus improving the security of the implementation of the generation of the ARQC 430 and the security of implementation of the transaction software 1 1 0. If necessary, a different module within the transaction software 1 10 (which may or may not be the calling module 71 0) may then carry out any other steps required to generate the authentication data, which is to be output to a terminal for authentication of the transaction, as described earlier. For example, if the result is the authentication data, it may be that no further steps need to be performed and the authentication data may simply be output to a terminal for authentication of the transaction, or it may be that the authentication data is modified in some way before being output to the terminal, or is included as only part of the output to the terminal.

In another example, the first and second parties may be configured to perform CA3 using MPC. Thus, the result returned by the first party 720 in step 760 may be SK2. By utilising MPC in this way, the initialisation vector 370 is not stored in its entirety in one location anywhere on the electronic device 1 00, thus improving the security of the implementation of CA3 and the transaction software 1 1 0. A different module within the transaction software 1 10 (which may or may not be the calling module 710) may then carry out any other steps necessary to generate the authentication data, which is to be output to a terminal for authentication of the transaction, as described earlier. For example, the result SK2 may be used to generate the PIN authentication data 390, which may then form at least part of the authentication data that is output to a terminal for authentication of the transaction, as described earlier.

In another example, the first and second parties may be configured to perform CA4 (and possibly CA3 too) using MPC. Thus, the result returned by the first party 720 in step 760 may be the PIN authentication data 390. Again, by utilising MPC, the initialisation vector 370 is not stored in its entirety in one location anywhere on the electronic device 1 00, thus improving the security of the implementation of the generation of the PIN authentication data 390 and the security of the implementation of the transaction software 1 10. If necessary, a different module within the transaction software 1 10 (which may or may not be the calling module 710) may then carry out any other steps required to generate the authentication data, which is to be output to a terminal for authentication of the transaction, as described earlier. For example, the PIN authentication data 370 may be combined with an ARQC 360 in order to form the authentication data to be output to the terminal, as described earlier.

In another example, the first and second parties may be configured to perform CA7 using MPC. Thus, the result returned by the first party 720 in step 760 may be the PIN authentication data 440. A different module within the transaction software 1 1 0 (which may or may not be the calling module 71 0) may then carry out any other steps necessary to generate the authentication data, which is to be output to a terminal for authentication of the transaction, as described earlier. For example, the PIN authentication data 440 may be combined with an ARQC 430 in order to form the authentication data to be output to the terminal, as described earlier.

In another example, the first and second parties may be configured to perform CA1 , CA2, CA3 and CA4 using MPC. Thus, the result returned by the first party 720 in step 760 may be the ARQC 360 and the PIN authentication data 390, or the PIN authentication data 390 and authentication data that is based at least in part on the ARQC 360, or authentication data that is based at least in part on the ARQC 360 and the PIN authentication data 390. A different module within the transaction software 1 1 0 (which may or may not be the calling module 710) may then carry out any other steps required to generate the authentication data, which is to be output to a terminal for authentication of the transaction, as described earlier. The first party 720 and the second party 730 may additionally, or alternatively, be configured to carry out any other cryptographic processes.

In another example, the first and second parties may be configured to perform CA5, CA6 and CA7 using MPC. Thus, the result returned by the first party 720 in step 760 may be the ARQC 430 and the PIN authentication data 440, or the PIN authentication data 440 and authentication data that is based at least in part on the ARQC 430, or authentication data that is based at least in part on the ARQC 430 and the PIN authentication data 440. A different module within the transaction software 1 1 0 (which may or may not be the calling module 710) may then carry out any other steps required to generate the authentication data, which is to be output to a terminal for authentication of the transaction, as described earlier. The first party 720 and the second party 730 may additionally, or alternatively, be configured to carry out any other cryptographic processes.

By configuring the first party 720 and the second party 730 in any of these ways, it is possible to more safely and securely carry out the cryptographic processes described earlier using software on the electronic device 100. In particular, the DK 320 and/or the initialisation vector 370 and/or the ATC 310 may not be exposed in their entirety in one location anywhere within the memory of the electronic device 1 00 and no single

party/application/module on the electronic device 1 00 or anywhere else will have access to the complete DK 320 and/or initialisation vector 370 and/or ATC 31 0. Thus, a secure element (SE) on the electronic device 100 is not required for storing any of the sensitive data, thereby simplifying the configuration of the electronic device 1 10 and reducing costs.

Additionally, or alternatively, the first party 720 and the second party 730 may be configured to generate the digital signature for the Off-line' authentication process described earlier (see, for example, Figure 6 and the associated description). As described earlier, the digital signature may be generated by using the device private key to digitally sign one or more items of information that are to be transmitted from the transaction software 1 10 to the POS 160. The calling module 710 may pass to the first party 720 in step 740 the one or more items of information to be digitally signed. The first and second parties may then jointly perform MPC in step 750 and return the digital signature in step 760.

Therefore, as described above in respect of the authentication data, it is possible to more safely and securely generate the digital signature using software on the electronic device 100. In particular, the device private key is not exposed in its entirety in one location within the memory of the device and no single party/application/module on the electronic 100, or anywhere else, has access to the complete device private key. Thus, a secure element (SE) on the electronic device 100 is not required for storing any of the sensitive data, thereby simplifying the configuration of the electronic device 100 and reducing costs.

The first and second parties may be configured to generate only a digital signature, which is returned in step 760 as the result, or generate only data relating the authentication data described above, which are returned in step 760 as the result, or generate both a digital signature and data relating to the authentication data described above, which all returned in step 760 as the result.

The authorisation system 171 may utilise the MPC processes described above in order to carry out the earlier described authentication process. In particular, the first party 720 and second party 730 may be implemented in software on the authorisation system 171 . The first and second parties may then jointly perform MPC in order to generate "test" (or second) authentication data, using which the authorisation system 171 may authenticate any authentication data received from the electronic device 100. Likewise, the POS 160 may utilise MPC to decrypt/validate the digital signature. In particular, the first party 720 and second party 730 may be implemented in software on the POS 160 and jointly perform MPC in order to decrypt/validate the digital signature and generate the unencrypted data output.

It will be appreciated that, in some embodiments, multiple cryptographic processes may be implemented using MPC. In some embodiments, each of those multiple cryptographic processes is implemented by its own respective first party 720 and second party 730. For example, if CA1 , CA2, CA3 and/or CA4 are to be implemented using MPC, then CA1 may be implemented using its own respective first party 720a and second party 730a; CA2 may be implemented using its own respective first party 720b and second party 730b; CA3 may be implemented using its own respective first party 720c and second party 730c; and CA4 may be implemented using its own respective first party 720d and second party 730d. Alternatively, the first party 720 and second party 730 may be arranged to implement multiple cryptographic process using MPC - for example, there may be a single first party 720 and a single second party 730 that, together, implement two or more of CA1 , CA2, CA3 and/or CA4 via MPC. The first party 720 and second party 730 may be arranged in analogous ways in respect of CA5, CA6 and/or CA7. The first party 720 may be programmed in a first programming language (for example, C,

C++, C#, Java, Fortran, Perl, assembly language, machine code, etc) and the second party 730 may be programmed in a second programming language (for example, C, C++, C#, Java, Fortran, Perl, assembly language, machine code, etc). The first programming language may be different from the second programming language, for example the first programming language may be C++ and the second programming language Java, or the first programming language may be Java and the second programming language Perl etc.

By writing the first party 720 using a programming language that is different to the programming language used to write the second party 730, the work effort required by an attacker to successfully attack both of the parties and obtain the first secret data from the first party 720 and the second secret data from the second party 730 is increased. Thus, the secret data stored in the first and second parties may be more difficult for an attacker to obtain, and the MPC processes be more difficult to understand and infiltrate/copy, thereby improving the security of the software. This may be particularly the case if, for example, one of the programming languages used is a compiled programming language (e.g. C or C++) whereas the other programming language used is not a compiled programming language and is, instead, a scripted or interpreted programming language (e.g. JavaScript).

Additionally, the programming (or code or instructions) of at least one of the first party 720 and/or second party 730 may be obfuscated, such that the code of the first party 720 and/or second party 730 are implemented as obfuscated code. Any known software obfuscation technique may be used, for example, any suitable obfuscation tools/libraries may be utilised. Further details regarding program obfuscation may be found, for example, at http://www.cs.princeton.edu/~boaz/Papers/obf_informal.html

By obfuscating at least one of the parties, the programming (or code or instructions) of that party or parties will be more difficult for an attacker to understand. Thus, the work effort required by an attacker to successfully attack an obfuscated party (or parties) will be even further increased, thus making it even more difficult for an attacker to obtain secret data stored in the party (or parties) and making the MPC processes more difficult to understand and infiltrate/copy, thereby further improving the security of the software.

The programming of both the first and second parties may be obfuscated such that the first party 720 is implemented as first obfuscated code and the second party is implemented as second obfuscated code. The obfuscation technique/methodology used for each of the parties may be different. This would even further increase the work effort required by an attacker to successfully attack the obfuscated parties, thus making it even more difficult for an attacker to obtain secret data stored in the parties, thereby even further improving the security of the software.

Whilst in the above described MPC implementations two parties jointly perform a cryptographic process using MPC to generate an result, it will be appreciated that any number of parties may be implemented in software on the electronic device 100 and jointly perform MPC to execute a cryptographic process to generate a result. For example, three or more parties may be implemented and each of the three or more parties may store respective secret data.

At least one of the three or more parties may be programmed using a different

programming language to one or more of the other parties. For example, two parties may be programmed using one programming language (such as C++) and one or more of the other parties may be programmed using a different programming language (such as Java). Alternatively, each of the three or more parties may be programmed using a different programming language, for example, a first party may be programmed using a first programming language (such as C), a second party may be programmed using a second programming language (such as Perl), a third party may be programmed using a third programming language (such as Java), etc.

At least one of the three or more parties may be implemented as obfuscated code. For example, the programming of all three or more parties may be obfuscated. The

obfuscation technique/methodology used for at least one of the three or more parties may be different to the technique/methodology used for one or more of the other parties. For example, two parties may be obfuscated using one obfuscation technique/methodology and one or more of the other parties may be obfuscated using a different obfuscation technique/methodology. Alternatively, each of the three or more parties may be obfuscated using a different obfuscation technique/methodology. For example, a first party may be obfuscated using a first obfuscation technique/methodology, a second party may be obfuscated using a second obfuscation technique/methodology , a third party may be obfuscated using a third obfuscation technique/methodology, etc. Whilst the above MPC implementations and techniques have been described above for use in mobile financial transactions using NFC, it will be appreciated that they may be utilised for any purpose where a cryptographic process is to be undertaken using software.

Any cryptographic process for encryption or decryption of data, or any other sort of cryptographic process, may be carried out using the MPC implementations described above. For example, the cryptographic process may comprise a data encryption or decryption process and/or a keyed hash function (which may be a cryptographic hash function, or any other function suitable for generating a message authentication code) for generating a message authentication code, and/or a process for generating a digital signature, and/or a process for validating or authenticating a message authentication code or a digital signature, etc.

Those processes may be carried out on a mobile electronic device, or on a static electronic device, or on a server, or a POS, or any other computing apparatus with a processor configured to execute a software program that is configured to perform one or more of the MPC processes described above.

Whilst the calling module 71 0, the first party 720 and second party 730 are all described as being modules (or 'applications' or 'sub-applications' or 'sub-modules') within the transaction software 1 10, it will be appreciated that one or more of those modules (or 'applications' or 'sub-applications' or 'sub-modules') may alternatively be implemented elsewhere within the electronic device 100. For example, the calling module 71 0 may form part of the transaction software 1 10 and each of the first party 720 and the second party 730 may be implemented as separate software instances (or 'modules' or 'applications') on the electronic device 100, separate from, but in direct or indirect communication with, the transaction software 1 10. Each of the first and second parties may be provisioned to the electronic device 1 00 along with the transaction software 1 10, or separately from the transaction software 1 10, for example as part of an update to the software.

Alternatively, only one of the first or second parties may be implemented as a module within the transaction software 1 10, with the other parties being implemented as a software module outside of the transaction software 1 10. The one or more parties that are implemented outside the transaction software 1 1 0 may be implemented as standalone modules (or 'applications'), or they may be implemented as part of another software module, for example another banking or financial

application/module/instance, or any other application/module/instance implemented in software on the electronic device 1 00. Thus, the functionality of at least one of the parties may be implemented as a module (or 'application' or 'sub-application' or 'sub-module') within another software application/module/instance on the electronic device 1 00. Where both the first and second parties are implemented outside of the transaction software 1 10, they may both be implemented as modules (or 'applications' or 'sub-applications' or 'sub- modules') within one other software application/module/instance, or the first party may be implemented as a module (or 'application' or 'sub-application' or 'sub-module') within a first other software application/module/instance and the second party may be implemented as a module (or 'application' or 'sub-application' or 'sub-module') within a second other software application/module/instance, or as a stand-alone second party software

i nstance/m od u le/appl icatio n . In all of these cases, each of the first and second parties may be provisioned to the electronic device 100 along with the transaction software 1 10, or separately from the transaction software 1 10, for example as part of an update to the software on the electronic device 100.

The provisioning system 172 may be configured to generate at least part of the software for performing the MPC process described above, or the software may be generated by a different system. Various other alternatives to the above aspects of the present disclosure may be readily appreciated.

For example, the processes shown in Figures 3 and 4 and described above may generate any type of authentication data that is suitable for the authentication of a transaction. For example, they may generate an ARQC, or any other type of message authentication code (MAC), or hashed message authentication code (HMAC), or another other suitable data.

Furthermore, the process of generating the authentication data may be different to that shown in Figure 3. For example, CA1 may be excluded altogether and CA2 may generate authentication data using a suitable cryptographic key (which may be DK 320, or any other key). The authentication data may be based on the device information 350 and any other suitable data, for example one or more of the internal card data 330, at least part of the transaction information 340, ATC 310 and/or any other suitable data. Furthermore, additional or alternative cryptographic algorithms to CA1 may be utilised.

Furthermore, for 'high-value' transactions, any process involving a user entered PIN may be undertaken. For example, CA3 may be omitted entirely and CA4 may use any suitable cryptographic key, for example SK1 or any other key. The PIN authentication data may be based on the user entered PIN and any other suitable data, for example the initialisation vector 370 and/or any other data. Furthermore, additional or alternative cryptographic algorithms to CA3 may be utilised. Alternatively, the authentication data generated by CA2 may be based at least in part on the user entered PIN 380.

Likewise, the process of generating the authentication data may be different to that shown in Figure 4. For example, CA5 may be excluded altogether and CA6 may generate authentication data using a suitable cryptographic key (which may be DK 320, or any other key). The authentication data may be based on the device information 350 and any other suitable data, for example one or more of the ATC 310, data relating to the transaction 340, the identifier of the virtual payment product 410 and the cryptographic version number (CVN) 420. Furthermore, where CA5 is included in the process, it may generate the hash, or any other suitable data such as a session key, based on the based on the device information 350 and any other suitable data, for example one or more of the ATC 310, data relating to the transaction 340, the identifier of the virtual payment product 410 and the cryptographic version number (CVN) 420. CA6 may then generate authentication data based on the output of CA5 and any other suitable data, for example any one or more of the above identified inputs that have not be used by CA5. Further, additional or alternative cryptographic algorithms to CA5 may be utilised.

Furthermore, for 'high-value' transactions, any process involving a user entered PIN may be undertaken. The PIN authentication data 440 may be based on the user entered PIN 380 and any other suitable data, for example the initialisation vector 370 and/or any other data. Furthermore, additional or alternative cryptographic algorithms to CA7 may be utilised. Alternatively, the authentication data generated by CA6 may be based at least in part on the user entered PIN 380.

Furthermore, a 'PIN transaction' may be required for transactions other than 'high-value' transactions. For example, the information relating to the transaction received by the electronic device 100 in Step S210 may indicate that a PIN transaction is required, regardless of the transaction value. For example, this may be implemented when purchasing age restricted products, paying for age restricted services such as gambling, or for any other reason.

The authentication information included in the transmission of Step S230 may take any form and may adhere to any suitable standards, for example EMVco standards.

The virtual transaction card provisioned on the transaction software 1 10 may be any type of financial transaction card, for example a credit card, debit card, prepayment card etc, from any card issuer. The provisioning system 172 may be configured to generate DK 320 and/or the initialisation vector 370 itself, or to instruct a different entity to generate one or both of DK 320 and/or the initialisation vector 370. The provisioning system 172 may store, in the database(s), the original value for DK 320, or may store other data that the authorisation system 171 can used to derive the original value of DK 320. Therefore, the DK 320 associated with the virtual transaction card may be obtained by retrieval or derivation. The same applies analogously to the PIN 380 and/or the initialisation vector 370 and/or the device information 350.

Whilst Figure 1 shows a direct data communication channel between the electronic device 100 and the host system 170, there may be any number of intervening elements, for example a mobile gateway etc. Likewise, there may also be any number of intervening elements in the data connection between the POS 160 and the host system 170.

Whilst the ATC 310 is described above as being implemented using an incremental counter, it may be implemented using any form of counter, for example a decremental counter, or any other means by which each transaction may be uniquely identified. It will be appreciated that the methods described have been shown as individual steps carried out in a specific order. However, the skilled person will appreciate that these steps may be combined or carried out in a different order whilst still achieving the desired result.

It will be appreciated that embodiments of the invention may be implemented using a variety of different information processing systems. In particular, although the figures and the discussion thereof provide an exemplary computing system and methods, these are presented merely to provide a useful reference in discussing various aspects of the invention. It will be appreciated that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or elements, or may impose an alternate decomposition of functionality upon various logic blocks or elements.

It will be appreciated that the above-mentioned functionality may be implemented as one or more corresponding software modules or components. Method steps implemented in flowcharts contained herein, or as described above, may each be implemented by corresponding respective modules; multiple method steps implemented in flowcharts contained herein, or as described above, may together be implemented by a single module.

It will be appreciated that, insofar as embodiments of the invention are implemented by software (or a computer program), then a storage medium and a transmission medium carrying the computer program form aspects of the invention. The computer program may have one or more program instructions, or program code, which, when executed by a computer carries out an embodiment of the invention. The term "program" or "software" as used herein, may be a sequence of instructions designed for execution on a computer system, and may include a subroutine, a function, a procedure, a module, an object method, an object implementation, an executable application, an applet, a servlet, source code, object code, a shared library, a dynamic linked library, and/or other sequences of instructions designed for execution on a computer system. The storage medium may be a magnetic disc (such as a hard drive or a floppy disc), an optical disc (such as a CD-ROM, a DVD-ROM or a BluRay disc), or a memory (such as a ROM, a RAM, EEPROM, EPROM, Flash memory or a portable/removable memory device), etc. The transmission medium may be a communications signal, a data broadcast, a communications link between two or more computers, etc.