BACKGROUND

[0001] The disclosure relates generally to a computer-implemented method for providing a secure data access, and more specifically, to a computer-implemented method for providing a secure data access service that encrypts data. The disclosure relates further to a data protection system for providing a secure data access service that encrypts data, and a computer program product.

[0002] Protecting enterprise or government data in any storage system but, in particular on cloud storage systems, is a must in view of the increasing number of cyber-attacks. Very often, sensitive data in the cloud are protected by an (hardware security module) (HSM) service. Examples of this are products like Key Protect or Hyper Protect Crypto Services from IBM. A data service uses the customer root key (CRK) in the respective HSM to give the client control over its data. Hence, the cloud operator may typically not access the encrypted data. This concept also includes a CRK rotation and cryptographic erasure of data by revoking the CRK, which means that the service can no longer access data.

[0003] However, the HSM is typically administered by a client administrator. Theoretically, as well as often practically, the user can access the data although, from an organizational perspective , the user shall not have access. So far, organizational processes have been used to prevent access to encrypted data by the customer or client operator. However, it has been proven that the organizational processes are not “water-tight” so that it would be useful to have a technical implementation for this.

[0004] There are several disclosures related to the encrypting of data. E.g., US Publication No. 2020/ 0195621 Al discloses a method, an apparatus and a computer program product for encrypting and decrypting data using multiple authority keys including receiving, from a first computing device, a data decrypt request to decrypt encrypted data and determining that the user key is associated with the key hierarchy that comprises the server key.

[0005] Additionally, Publication No. US 2019/0173674 Al discloses a method facilitating and enabling key encryption key (KEK) rotation for a running multi-tenant system without requiring system downtime or interruption The example method facilitates decrypting a set of one or more DEKs using a preexisting KEK; using a new KEK to re-encode the DEKs using the new KEK, all while simultaneously enabling servicing of tenant requests.

[0006] However, the disadvantage of known solutions may be that an access by an individual and malicious administrator cannot be completely prevented.

[0007] Hence, there may be a need to overcome this security hole and technically prevent that a single operator or administrator may access encrypted data without authorization.

SUMMARY

[0008] According to an aspect of the present disclosure, a computer-implemented method provides a secure data access service that encrypts data may be provided. The method may comprise wrapping a data encryption key by at least two customer root keys, wherein the at least two customer root keys are assigned to different user identifiers, and wherein the at least two customer root keys are stored in different hardware security modules, and wherein a wrapping structure for the at least two customer root keys is applied according to an access policy that defines which of the assigned user identifiers must concur to enable a data access to the encrypted data by the secure data access service. Moreover, the method may comprise encrypting the data by the secure data access service using the unwrapped data encryption key.

[0009] According to another aspect of the present disclosure, a data protection system provides a secure data access service that encrypts data may be provided. The system may comprise a processor and a memory, communicatively coupled to the processor, wherein the memory stores program code portions that, when executed, enable the processor, to wrap a data encryption key by at least two customer root keys, wherein the at least two customer root keys are assigned to different user identifiers, and wherein the at least two customer root keys are stored in different hardware security modules, and wherein a wrapping structure for the at least two customer root keys is applied according to an access policy that defines which of the assigned user identifiers must concur to enable a data access to the encrypted data by the secure data access service. The processor may further be enabled to encrypt the data by the secure data access service using the unwrapped data encryption key.

[0010] The proposed computer-implemented method for providing a secure data access service that encrypts data may offer multiple advantages, technical effects, contributions and/or improvements:

[0011] In general, sensitive, encrypted data may be protected much better with the technical concept proposed here. Advantageously, it may be prevented that a single operator or administrator may access encrypted data alone and without any third party control. This is achieved by a double ownership of the data, i.e., the novel access method. Thereby, it may be technically enforced that a data access may only be possible if two customer root keys are used in combination in order to unwrap a data encryption (decryption) key. The at least two customer root keys used to protect the data encryption key or the data access key are protected by hardware security modules which are linked to individual user IDs of the respective operators. Hence, at least two operators or administrators may be required independently in order to facilitate any access to the sensitive data.

[0012] Thereby, in particular in cloud computing environments, the impossible and un-allowed data access by the cloud storage provider may remain intact. Furthermore, it may also be enforced, that one of the at least two customer root keys may be controlled by an official governmental or other enabled authority.

[0013] As a consequence, in an illustrative example, the situation where on operator alone may have access to the salary of an executive director of the company can be completely avoided.

[0014] Another aspect is that each owner of a customer root key can unilaterally block access to data. Use cases of this aspect include cryptographically erasing content by disabling access to the data in the clear by disabling access to the data encryption key used for the actual data. [0015] In the following, additional embodiments of the disclosure, applicable for the method as well as for the system, will be described.

[0016] According to embodiments, the wrapping structure may define a sequence of application of the at least two customer root keys for the wrapping of the data encryption key. The wrapping structure may be defined as a part of the access policy in which it may also be defined that a multi-user root key may have to be used to encrypt or decrypt the data encryption key DEK. Alternatively, the sequence of application of the at least two customer root keys may be defined within the secure data access service or in a storage, only accessible by the secure data access service. A useful sequence of wrapping may be defined by ascending or descending order of the customer root keys. This approach is also expandable to a plurality of customer root keys.

[0017] According to an embodiment, the secure data access service may store only the wrapped data encryption key wDEK. Hence, the unwrapped data encryption key may only be available within the secure data access service as long it may be required to encrypt or decrypt the data associated with it. This way, the secure data access service may be constructed in a temper- proven way. Alternatively, the secure data access service may only comprise a pointer to the wrapped data encryption and/or decryption key.

[0018] According to an advantageous embodiment, the different hardware security modules may be physical different hardware security modules (HSM), virtual different hardware security modules or a mixture thereof. Using an HSM (or more) has been proven to be one of the safest methods to protect data against unauthorized access. The proposed concept brings this level of security again to a higher level.

[0019] According to a further embodiment, the at least two customer root keys are n customer root keys out of m customer root keys, wherein m > n. This may expand the level of protection even further as more customer root keys may be required, i.e., more than two operators with related user or operator identities (i.e., user IDs) may be required for an allowed data access. Moreover, this approach adds flexibility. As an example: If five operators are generally allowed to have access rights to the secure data, it can be defined that only any combination of two or three or four or five operators may be needed to access the data. In general, the number of possible combinations may be determined by the formula (m! / n! *(m-n), wherein m is comparably close to n).

[0020] Furthermore, from an organizational perspective, which may also be enabled by a technical implementation, one of the n customer root keys may belong to a regulatory authority. Hence, the operators may never be allowed to access the data by a combination of them alone. It may always be required to have a regulator as part of the group. As a consequence, very sophisticated policies can be implemented through appropriate wrapping schemes.

[0021] According to a further embodiment, the at least two customer root keys may be symmetric encryption/ decry ption keys. Because none of the keys may be transported along publicly accessible communication lines, a symmetric key may be sufficient. Hence, only one encryption/decryption key may be required by the secure data access service and it may be easier to define the sequence according to which the customer root keys may have to be applied.

[0022] According to another optional embodiment, the at least two customer root keys may have to be different. This may further enhance data security because it may be enforced that none of the at least two customer root keys may have the same value. Hence, no single human operator may get access to the data by logging in with two user IDs and using the same customer root key.

[0023] According to a further embodiments, the data encryption key may be a symmetric or asymmetric key. Thereby, the wrapping keys, i.e., the customer root keys, may be used to wrap the symmetric encryption/decryption key or the asymmetric key pair for encryption and decryption. This may be useful if the data may be encrypted and decrypted at different ends of a public communication line.

[0024] According to another embodiment, the data encryption key may only be valid for a limited time window. Also this feature may increase data security. If the data encryption key may expire, the data may have to be decrypted with the old encryption key (if it is a symmetric key) and encrypted again with then new data encryption key. Furthermore, the new data encryption key may have to be wrapped with the at least two customer root keys. From there on, only the new data encryption key may enable a proper encryption as well as a decryption of the secured data.

[0025] According to another embodiment, the wrapping structure may define a sequence of application of the at least two customer root keys for an unwrapping of the data encryption key. Hence, for the wrapping of the data encryption/ decry ption key and the unwrapping of the data encryption/decryption key, the same sequence may be enforced. Typically, this is a consequence of the symmetric character of the customer root keys. This may also be codified in the access policy.

[0026] According to another embodiment, the unwrapped data encryption key may be passed from a security service to another data access function for a final data access. Thus, the data encryption key is not used directly for a data access but it may pass the unwrapped data access key to another service which then may access the data. This may be a useful approach to service chaining. Thus, the secure data access service may provide its wrapping/unwrapping service for several other services that ultimately accessing the data. Hence, a central control of the wrapping/unwrapping may exist in a complex service-oriented architecture (SOA). Such architecture may enhance successfully legacy installations and may improve a more central any coordinated control of a data access.

[0027] Furthermore, embodiments may take the form of a method, related computer program product, accessible from a computer-usable or computer-readable medium providing program code for use, by, or in connection, with a computer or any instruction execution system. For the purpose of this description, a computer-usable or computer-readable medium may be any apparatus that may contain means for storing, communicating, propagating or transporting the program for use, by, or in connection, with the instruction execution system, apparatus, or device.

BRIEF DESCRIPTION OF THE DRAWINGS [0028] It should be noted that embodiments of the disclosure are described with reference to different subject-matters. In particular, some embodiments are described with reference to methods, whereas other embodiments are described with reference to apparatus. However, a person skilled in the art will gather from the above and the following description that, unless otherwise specifically disclosed, in addition to any combination of features belonging to one type of subject matter, any combination between features relating to different subject matters, in particular, between features of the method, and features of the apparatus and systems and computer program products, is considered as to be disclosed within this document.

[0029] The aspects defined above and further aspects of the present disclosure are apparent from the examples of embodiments to be described hereinafter and are explained with reference to the examples of embodiments, to which the disclosure is not limited.

[0030] Preferred embodiments of the disclosure will be described, by way of example only, and with reference to the following drawings:

FIG. 1 shows a block diagram of an embodiment of the inventive computer-implemented method for providing a secure data access service that encrypts data.

FIG. 2 shows a block diagram of an embodiment of components instrumental for the proposed concept.

FIG. 3 shows a block diagram of an embodiment of the inventive data protection system for providing a secure data access service that encrypts data.

FIG. 4 shows an embodiment of a computing system comprising the system according to FIG. 3.

DETAILED DESCRIPTION

[0031] In the context of this description, the following conventions, terms and/or expressions may be used: [0032] The term 'secure data access service' may denote the data service proposed here accessing encrypted data, or encrypting them, with a data access key DEK which may be wrapped by at least two customer root keys.

[0033] The term 'encrypted data' may denote the known process in cryptography by which information or data may be encoded by a key. The key may be a symmetric key or in an asymmetric key. Encrypted data may only be accessed again if the decryption key is known.

[0034] The term 'hardware security module' may denote a physical computing device that may safeguard and manage digital data access keys. It may also enable and perform an encryption and decryption for digital signatures, strong authentication and other cryptographic functions. Such hardware security modules are typically used in enterprise class computer systems.

[0035] The term 'wrapping structure' may denote a sequence by which a plurality of wrapping keys may be applied in order to protect data, i.e., a data encryption key.

[0036] The term 'access policy' may denote rules according to which a data access to certain data may be allowed. Often, data access policies reflect organizational requirements. However, it may also be possible that specific technical rules are defined in the access policy which need to be applied to decrypt data in a sequential way. E.g., if a plurality of customer root keys may be required to decrypt a data encryption key, the access policy may define that the keys have to be applied in an, e.g., ascending or descending (or any other predefined) order of the key identifiers or the keys itself.

[0037] The term 'data encryption key' may denote a digital bit sequence required to encode data. In addition, a data decryption key may denote a digital bit sequence required to decode the data again.

[0038] The term 'wrapped data encryption key' may denote a data encryption key which may again be encrypted, i.e., wrapped, by a wrapping key. [0039] In the following, a detailed description of the figures will be given. All instructions in the figures are schematic. Firstly, a block diagram of an embodiment of the computer- implemented method provides a secure data access service that encrypts data is given. Afterwards, further embodiments, as well as embodiments of the data protection system which provides a secure data access service that encrypts data will be described.

[0040] FIG. 1 shows a block diagram of a preferred embodiment of the computer-implemented method 100 for providing a secure data access service that encrypts data. The method 100 comprises, for example, wrapping, 102, a data encryption key, and potentially also a decryption key, in case of an asymmetric key pair, by at least two customer root keys. Thereby, the at least two customer root keys are assigned to different user identifiers, and the at least two customer root keys are stored in different hardware security modules. Furthermore, a wrapping structure for the at least two customer root keys is applied according to an access policy that defines which of the assigned user identifiers must concur to enable a data access to the encrypted data by the secure data access service. One of the access policies may define the sequence by which the unwrapping the two customer root keys has to be performed. Alternatively, this unwrapping sequence may also be codified within the secure data access service. Furthermore, also an “m out of n” rule may be defined by the access policy.

[0041] Furthermore, the method 100 comprises encrypting, 104, the data by the secure data access service using the unwrapped data encryption key. To secure the data by the data encryption key, any known encryption method may be used. Hence, the disclosure does not limit or negatively influence the use of the data encryption key in any form.

[0042] FIG. 2 shows a block diagram 200 of an embodiment of components instrumental. The secure data access service 202 manages the access to the persistent data 204 which are encrypted by the data encryption key DEK which may, typically but not necessary, be a symmetric data access key. The data may be stored as part of the secure data access service or externally. Furthermore, the secure data access service 202 may also be implemented directly into a hardware device like a storage system. The persistent data may be part of the secure data access service 202 (as shown) or its persistent storage can be managed outside the secure data access service 202. [0043] The DEK 210 will not be stored unwrapped in the secure data access service 202. Hence, in an unwrapped form, it will have only a transient character. The DEK 210 can only be accessed when it is unwrapped using a second of at least two customer root keys CRK2. DEK 210 wrapped with the customer root key 2, 208, is also only available in transient form in the secure data access service 202.

[0044] A second wrapping layer, in particular, by the first of the at least two customer root keys, is securing DEK 210 by the customer root key 2. Hence, DEK 210 is wrapped twice. However, the customer root keys are typically not even available in transient form in the secure data access service 202. Only the double wrapped DEK 210 is available in the form DEK(w2)(wl) 206.

[0045] The customer root keys CRK1 214 and CRK2 218 are stored independently of each other in the hardware security modules and/or a related service HSM svc 1 212 and HSM svc2 216. If the secure data access service needs to encrypt or decrypt the data, the secure data access service 202 requests an unwrapped operation on DEK(w2)(wl) 206 and DEK(w2) from the respective HSM svc 1 212 and HSM svc2 216. In case more customer root keys are required, even more calls to the respective HSMs are required.

[0046] As a consequence, and in contrast to existing technologies, none of the administrators or operators 222, 226 can access the persistent data 204 independently of one another. Operator 222, using the user ID 220 of admin 1, may enable or set the customer root key 1; whereas operator 226, using the user ID 224 of admin2, may independently enable or set the customer root key 2.

[0047] It may be noted that this implementation form represents a basic version. However, implementations with more than two customer root keys or an “m out of n” implementation would be done accordingly with more wrapping layers.

[0048] The flow between the just mentioned components can be summarized as follows: During the instantiation of the secure data access service, the following happens. The data service instantiation is started by specifying customer root key identifiers and related HSMs as well as the required access policy for the service. Then, the data service generates the data encryption key DEK which is used for the actual data encryption (as well as the decryption in case of a symmetric key). The secure data access service generates a list of combinations to support the required access policy. Thereby, for each combination, the secure data service defines the order of the CRKs to be used for wrapping. For example, this may be done in an ascending order of key -IDs. However, any other rule may be applied for the ordering of the wrapping/dewrapping. Next, the secure data access service sequentially asks the related HSMs in combination to incrementally wrap or unwrapped the data encryption key DEK, i.e., wrapping wrapped DEK, etc.

[0049] During the use of the secure data access service the following happens: If the unwrapped, i.e., transient, DEK is not available, e.g., because it has expired, the secure data access service selects the order that satisfies the access policy (e.g., in a 3-out-of-5 scenario: attempt 1- 2-3) and the secure data access service selects the multiple wrapped DEK and unwraps it in the given order (e.g., by an ascending or descending key-IDs). If one of the HSMs refuses to support the data service, e.g., in case the key is suspended or revoked, the secure data access service starts over, using the next sensible combination (e.g., if unwrapped with 2 failed: start over was 1-3-4). Finally, the unwrapped (i.e., transient) DEK is used for the data access operation.

[0050] FIG. 3 shows a block diagram of an embodiment of the data protection system 300 which provides a secure data access service that encrypts data. The data protection system 300(in short, system 300) comprises a processor 302 and a memory 304, communicatively coupled to the processor 302, wherein the memory 304 stores program code portions that, when executed, enable the processor 302, to wrap - in particular, by a wrapping module 306 of the secure data access service module 310 - a data encryption key by at least two customer root keys. Thereby, the at least two customer root keys are assigned to different user identifiers, and the at least two customer root keys are stored in different hardware security modules. Furthermore, a wrapping structure for the at least two customer root keys is applied according to an access policy that defines which of the assigned user identifiers must concur to enable a data access to the encrypted data by the secure data access service. [0051] Additionally, the processor 302 is enabled to encrypt - in particular, by an encryption unit of the secure data access service module 310 (c.f., FIG. 2, 202) the data by the secure data access service using the unwrapped data encryption key.

[0052] It shall be understood that all functional units, modules and functional blocks, in particular, the processor 302, the memory 304, the secure data access service module 310, as well as the wrapping module 306 and encryption unit 308, may be communicatively coupled to one another for signal or message exchange in a selected 1 : 1 manner. Alternatively the functional units, modules and functional blocks can be linked to a system internal bus system 312 for a selective signal or message exchange.

[0053] Embodiments of the disclosure may be implemented together with virtually any type of computer, regardless of the platform being suitable for storing and/or executing program code. FIG. 4 shows, as an example, a computing system 400 suitable for executing program code related to the proposed method.

[0054] The computing system 400 is only one example of a suitable computer system, and is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the invention described herein, regardless, whether the computer system 400 is capable of being implemented and/or performing any of the functionality set forth hereinabove. In the computer system 400, there are components, which are operational with numerous other general purpose or special purpose computing system environments or configurations. Examples of well-known computing systems, environments, and/or configurations that may be suitable for use with computer system/server 400 include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments that include any of the above systems or devices, and the like.

Computer system/server 400 may be described in the general context of computer systemexecutable instructions, such as program modules, being executed by a computer system 400. Generally, program modules may include routines, programs, objects, components, logic, data structures, and so on that perform particular tasks or implement particular abstract data types. Computer system/server 400 may be practiced in distributed cloud computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed cloud computing environment, program modules may be located in both, local and remote computer system storage media, including memory storage devices.

[0055] As shown in the figure, computer system/server 400 is shown in the form of a general- purpose computing device. The components of computer system/server 400 may include, but are not limited to, one or more processors or processing units 402, a system memory 404, and a bus 406 that couple various system components including system memory 404 to the processor 402. Bus 406 represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example, and not limiting, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnects (PCI) bus. Computer system/server 400 typically includes a variety of computer system readable media. Such media may be any available media that is accessible by computer system/server 400, and it includes both, volatile and non-volatile media, removable and non-removable media.

[0056] The system memory 404 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 408 and/or cache memory 410. Computer system/server 400 may further include other removable/non-removable, volatile/non- volatile computer system storage media. By way of example only, a storage system 412 may be provided for reading from and writing to a non-removable, non-volatile magnetic media (not shown and typically called a 'hard drive'). Although not shown, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a 'floppy disk'), and an optical disk drive for reading from or writing to a removable, non-volatile optical disk such as a CD-ROM, DVD-ROM or other optical media may be provided. In such instances, each can be connected to bus 406 by one or more data media interfaces. As will be further depicted and described below, memory 404 may include at least one program product having a set (e.g., at least one) of program modules that are configured to carry out the functions of embodiments of the invention. [0057] The program/utility, having a set (at least one) of program modules 416, may be stored in memory 404 by way of example, and not limiting, as well as an operating system, one or more application programs, other program modules, and program data. Each of the operating systems, one or more application programs, other program modules, and program data or some combination thereof, may include an implementation of a networking environment. Program modules 416 generally carry out the functions and/or methodologies of embodiments of the invention, as described herein.

[0058] The computer system/server 400 may also communicate with one or more external devices 418 such as a keyboard, a pointing device, a display 420, etc.; one or more devices that enable a user to interact with computer system/server 400; and/or any devices (e.g., network card, modem, etc.) that enable computer system/server 400 to communicate with one or more other computing devices. Such communication can occur via Input/Output (VO) interfaces 414. Still yet, computer system/server 400 may communicate with one or more networks such as a local area network (LAN), a general wide area network (WAN), and/or a public network (e.g., the Internet) via network adapter 422. As depicted, network adapter 422 may communicate with the other components of the computer system/server 400 via bus 406. It should be understood that, although not shown, other hardware and/or software components could be used in conjunction with computer system/server 400. Examples, include, but are not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc.

[0059] Additionally, the data protection system 300 for providing a secure data access service that encrypts data may be attached to the bus system 406.

[0060] The descriptions of the various embodiments of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skills in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skills in the art to understand the embodiments disclosed herein. [0061] The present invention may be embodied as a system, a method, and/or a computer program product. The computer program product may include a computer readable storage medium(or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention.

[0062] The medium may be an electronic, magnetic, optical, electromagnetic, infrared or a semi - conductor system for a propagation medium. Examples of a computer-readable medium may include a semi-conductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read - only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk - read only memory (CD- ROM), compact disk-read / write (CD R/W), DVD and Blu-Ray -Disk.

[0063] The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non - exhaustive list of more specific examples of the computer readable storage medium includes the following : a portable computer diskette, a hard disk, a random access memory (RAM), a read - only memory (ROM), an erasable programmable read - only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disk read - only memory (CD - ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch - cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber - optic cable), or electrical signals transmitted through a wire.

[0064] Computer readable program instructions described herein can be downloaded to respective computing / processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing / processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing / processing device.

[0065] Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state - setting data, or either source code or object code written in any combination of one or more programming languages, including an object-oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the C programming language or similar programming languages. The computer readable program instructions may execute entirely on the user's computer, partly on the user's computer as a stand - alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention.

[0066] Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. [0067] These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function / act specified in the flowchart and/or block diagram block or blocks.

[0068] The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatuses, or another device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatuses, or another device implement the functions / acts specified in the flowchart and/or block diagram block or blocks.

[0069] The flowcharts and/or block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s).In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware - based systems that perform the specified functions or act or carry out combinations of special purpose hardware and computer instructions. [0070] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms a, an and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will further be understood that the terms comprises and/or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0071] The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements, as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skills in the art without departing from the scope and spirit of the disclosure. The embodiments are chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skills in the art to understand the disclosure for various embodiments with various modifications, as are suited to the particular use contemplated.

A summary is provided below:

A computer-implemented method which provides a secure data access service that encrypts data, the method comprising wrapping a data encryption key by at least two customer root keys, the at least two customer root keys are assigned to different user identifiers, the at least two customer root keys are stored in different hardware security modules, and a wrapping structure for the at least two customer root keys is applied according to an access policy that defines which of the assigned user identifiers must concur to enable a data access to the encrypted data by the secure data access service, and encrypting the data by the secure data access service using the unwrapped data encryption key. 1. The method according to clause 1, wherein the wrapping structure defines a sequence of application of the at least two customer root keys for the wrapping of the data encryption key.

2. The method according to clause 1 or 2, wherein the secure data access service stores only the wrapped data encryption key.

3. The method according to any of the preceding clauses, wherein the different hardware security modules are physical different hardware security modules, virtual different hardware security modules or a mixture thereof.

4. The method according to any of the preceding clauses, wherein the at least two customer root keys are n customer root keys out of m customer root keys, wherein m < n.

5. The method according to any of the preceding clauses, wherein the at least two customer root keys symmetric encryption/decryption keys.

6. The method according to any of the preceding clauses, wherein the at least two customer root keys have to be different.

7. The method according to any of the preceding clauses, wherein the data encryption key is a symmetrical or asymmetric key.

8. The method according to any of the preceding clauses, wherein the data encryption key is only valid for a limited time window.

9. The method according to any of the preceding clauses, wherein the wrapping structure defines a sequence of application of the at least two customer root keys for an unwrapping of the data encryption key.

10. The method according any of the preceding clauses, wherein the unwrapped data encryption key is passed from a security service to another data access function for a final data access. 11. A data protection system for providing a secure data access service that encrypts data, the data protection system comprising a processor and a memory, communicatively coupled to the processor, wherein the memory stores program code portions that, when executed, enable the processor, to wrap a data encryption key by at least two customer root keys, the at least two customer root keys are assigned to different user identifiers, the at least two customer root keys are stored in different hardware security modules, and a wrapping structure for the at least two customer root keys is applied according to an access policy that defines which of the assigned user identifiers must concur to enable a data access to the encrypted data by the secure data access service, and encrypt the data by the secure data access service using the unwrapped data encryption key.

12. The data protection system according to clause 12, wherein the wrapping structure defines a sequence of application of the at least two customer root keys for the wrapping of the data encryption key.

13. The data protection system according to clause 12 or 13, wherein the secure data access service stores only the wrapped data encryption key.

14. The data protection system according to any of clauses 12 to 14, wherein the different hardware security modules are physical different hardware security modules, virtual different hardware security modules or a mixture thereof.

15. The data protection system according to any of clauses 12 to 15, wherein the at least two customer root keys are n customer root keys out of m customer root keys, wherein m < n.

16. The data protection system according to any of clauses 12 to 16, wherein the at least two customer root keys are symmetric encryption/ decry ption keys.

17. The data protection system according to any of clauses 12 to 17, wherein the at least two customer root keys have to be different. 18. The data protection system according to any of clauses 12 to 18, wherein the data encryption key is only valid for a limited time window.

19. A computer program product for a data protection system, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions being executable by one or more computing systems or controllers to cause the one or more computing systems to wrap a data encryption key by at least two customer root keys, the at least two customer root keys are assigned to different user identifiers, the at least two customer root keys are stored in different hardware security modules, and a wrapping structure for the at least two customer root keys is applied according to an access policy that defines which of the assigned user identifiers must concur to enable a data access to the encrypted data by the secure data access service, and encrypt the data by the secure data access service using the unwrapped data encryption key.