This invention relates to security devices and to systems incorporating such devices, and is especially applicable to security devices in the form ot portable secure objects and associated systems The term portable secure object is well known and commonly used by those skilled in the art, to indicate a small portable object such as a credit card or smart card or a smart electronic key, which contains personal, commercial or other information in analogue or digital form which a user wishes to iemain secure, usually from use or access by unauthorised persons This invention is particularly applicable to arrangements using smart cards such as are described in the co-pending International patent application No PCT/GB97/01451 but may be applied to other systems using any card or other poi table secure object containing information which needs to be accessed by means of an acoustic, electrical, electronic, mechanical or vibrational transducer In the arrangement described in patent application No PCT/GB97/01451 an acoustic interface is provided to enable a person in possession ot a smart card to input a voice signal as a biometπc feature to a card reader machine into which the card has been inserted in order to confirm the identity ot the speaker and thus permit access by the speaker to the information on the card or in the system to which the card is inserted or otherwise applied In such systems the voice biometπc data may be coded appropriately and stored on the card or in some centralised store for retrieval and comparison

It is has been found that a major problem in embodying and using such systems is that the characteristics ot input microphones or othei input transducer^ vary significantly, such that the sound patterns generated and stoied during registration may not match the sound patterns produced by the individual during interrogation, even if the subject speaker spoke his or her input phrase in an identical fashion Microphone and transducer variability therefore is a major advei se feature of such systems which prevents or precludes their widespread

use.

It is an object of the present invention to provide an improved system whereby the problem related to microphone variability is substantially overcome. According to one aspect of the present invention there is provided a security device comprising a portable secure object which includes means for storing e.g. confidential information, means for storing a coded sound signal or a signal indicative thereof, and integral microphone means, said microphone means being adapted for use in generating said coded sound signal during a registration procedure, and subsequently for use in deriving a further coded sound signal for comparison with said generated coded sound signal for subsequent interrogation purposes.

In carrying out the invention it may be arranged that said coded sound signal is stored in said portable secure object or alternatively is stored remotely from said portable secure device. Preferably, the said portable secure object takes the form of a magnetic stripe swipe card, an electronic smart card, or a plastic card having bar coded information thereon.

According to a second aspect of the present invention there is provided a security system adapted for use with a security device as aforesaid, said system comprising means for receiving said security device, sound transmission means for transmitting a sound signal input to said system to die microphone means of said security device, signal processing means responsive to an electrical signal from said microphone means for generating a coded signal indicative of said sound signal, and means for applying a signal to said security device corresponding to said coded signal.

In carrying out the invention according to the second aspect it may be arranged that said system comprises means for receiving said security device, sound transmission means for transmitting a sound signal input to said system to the microphone means of said security device, signal processing means responsive to an electrical signal from said microphone means for generating a

coded signal indicative of said sound signal, means responsive to a signal stored in said security device for generating a coded sound signal, comparison means for comparing the generated coded sound signal with the coded sound signal generated by said processing means and for permitting access to the confidential information stored on said portable security device in dependence upon the correspondence therebetween.

In a preferred system said signal processing means comprises a plurality N of signal comparators, each signal comparator being adapted to compare the electrical signal from said microphone means with a plurality of different exemplar signals and for affording an output indicative of which of said exemplar signals corresponds most closely to said electrical signal, the sets of exemplar signals of each of said signal comparators being different, said electrical signal being input to each of said signal comparators to derive an N-part coded signal which is indicative of said sound signal. Advantageously each of said signal comparators will be based on TESPAR coding.

An exemplary embodiment of the invention will now be described, reference being made to the accompanying drawings, in which:

Fig. 1 is a schematic circuit diagram of a security device in accordance with the present invention in the form of a card reader terminal adapted for Registration purposes for use in conjunction with a portable secure object in accordance with the present invention in the form of a magnetic stripe swipe card; and

Fig. 2 is a schematic diagram of the security device of Fig. 1 , adapted for Interrogation purposes. In Fig. 1 of the drawings there is depicted a card reader terminal 1 which is closely based on the arrangement disclosed in Fig. 7 of the aforesaid International patent application No. PCT/GB97/001451 and which includes signal processing which is described in great detail in that application.

The card reader terminal 1 of Fig. 1 differs from that disclosed in Fig. 7 of the aforesaid International application in that the need for the microphone

which forms an integral part of the card reader terminal of Fig. 7 is obviated by fabricating a microphone actually on the swipe card as will be explained.

The card reader terminal 1 comprises a card receiving slot 2 into which a magnetic stripe swipe card 3 can be inserted by a user. The swipe card 3, as has been explained, is provided with an integrally formed microphone module 4 which, when the card is located in die slot 2 of the card reader terminal 1 locates adjacent the lower end 5 of an acoustic conduit 6 which extends upwards and terminates on the side face of the terminal 1 at a speech input cone 7. The slot 2 of the card reader terminal 1 is also provided with means (not shown) for making an electrical connection to the card 3 when it is located in the slot 2 so that the electrical output from the microphone module 4 may be fed via connection 8 to signal processing circuitry 9 including a TESPAR coder 10 as described in detail in the aforesaid International application, and which results in Registration data corresponding to a coded sound signal being stored in a digital output store 11 which forms part of the signal processing circuitry 9. The Registration data corresponding to the coded sound signal stored in the digital output store 11 is fed via output 12 and is read into the magnetic stripe of the swipe card 3.

The operation of the security system of Fig. 1 is as follows:- When a user wishes to register, a blank magnetic swipe card 3 is issued to him and is inserted in the slot 2 of the card reader terminal 1. The terminal 1 will then prompt the user to speak into the speech input cone 7. The speech input is then fed via the acoustic conduit 6 to the microphone module 4 on the swipe card 3, and the electrical output from it is fed to the signal processing circuitry 9 in the terminal 1 which generates the Registration data in the form of the coded sound signal which is stored in the digital output store 11 and which is read into the magnetic stripe of the swipe card 3.

In Fig. 2 of the drawings there is depicted the card reader terminal 1 of Fig. 1 adapted for card Interrogation purposes and is closely based on the arrangement disclosed in Fig. 6 of the aforesaid International application.

For Interrogation purposes, a user having in his possession a swipe card 3 having Registration data contained in the magnetic stripe thereof along with confidential data relating to the user, inserts the card 3 in the slot 2 of the card reader terminal 1 and the Registration data stored on the card 3 is read into a Registration data store 13. The terminal 1 then prompts the user to speak into the speech input cone 7 of the terminal 1. The speech input is then processed as has been described with reference to Fig. 1 and results in Interrogation data being stored in the digital output store 11 . The Interrogation data in the digital output store 1 1 is compared in a comparator 14 with the Registration data stored in the Registration data store 13 and a pass/fail output 15 is afforded.

A "pass" output is afforded if the comparison between the Interrogation data and the Registration data indicates a close match and enables the user to complete his transaction including providing access to the confidential information contained on his swipe card 3. A "fail " output is afforded if the comparison between the Interrogation data and the Registration data indicates that there is not a close match and prevents any transaction involving the swipe card 3 from proceeding.

As will be appreciated from the security system described with reference to Figs. 1 and 2 of the accompanying drawings, the microphone module 4 fabricated on the swipe card 3 is used for both registration and all interrogation purposes and accordingly overcomes the problems associated with using different microphones.

It will be appreciated that the microphone module 4 may take any convenient form and may be a simple piezo-electric thin film transducer which may form all or part of the substrate of the card . Alternatively, a silicon micromachined microphone such as that marketed by Noise Cancellation Technologies, Inc. , of the U.S. , fabricated integrally with a smart card microprocessor chip, or other forms of microphone such as those disclosed in U .S. patent Nos. 5146435, 5216490 and 5452268 may be used. It should be appreciated that the arrangements which have been described

have been given by way of example only and it will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the invention. For example, the acoustic conduit may take any convenient form and may be air filled or may comprise any appropriate vibration conducting material such as metal, fluid, liquid, gas, etc, or even foam. Also, instead of storing the Registration data in the form of a coded sound signal on the swipe card 3, it may be stored remotely e.g. at the terminal 1 or centrally and a coded signal corresponding to the coded sound signal may be stored on the card 3.