AU748808B2 - 3D human subject identification and authentication system - Google Patents

Description

S&FRef: 503022

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: 0 0 0 0.0.

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.00.0 0*0:0 oo Actual Inventor(s): Address for Service: Invention Title: Canon Kabushiki Kaisha 30-2, Shimomaruko 3-chome, Ohta-ku Tokyo 146 Japan Sue-Ken Yap Spruson Ferguson St Martins Tower 31 Market Street Sydney NSW 2000 3D Human Subject Identification and Authentication System ASSOCIATED PROVISIONAL APPLICATION DETAILS [33] Country [31] Applic. No(s) AU PQ0404 [32] Application Date 17 May 1999 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815c -1- 3D HUMAN SUBJECT IDENTIFICATION AND AUTHENTICATION SYSTEM Technical Field of the Invention The present invention relates generally to human identification and, in particular, to secure human identification and authentication. The invention also relates to a computer program product comprising a computer readable medium having recorded thereon a computer program for identifying humans and authenticating the identification.

Background Art Conventional identification systems used for the purpose of identifying a human subject to allow entry into an area (eg. a country or a restricted security area) generally :i 10 rely on photographs. A person presents their personal photo identification (ID) to a security officer who authenticates the ID by comparing the photo to the person. These photo ID's can comprise a watermark which is impressed on the ID during its manufacture and becomes visible when the ID is viewed in the light at a certain angle.

The watermark aids in authentication of the ID in that it is more difficult to forge than the photo. However, photo IDs only present to the security officer one particular perspective image of the person concerned and that image can be dependent on the quality of the photo. Further, photo IDs can be easily counterfeited which is illustrated by the huge black market in counterfeit passports.

A more recent development in the field of human subject identification is biometrics, which measures some biological characteristic of the individual. A sample (eg. saliva) is taken from a human subject and analysed. The results of the analysis are kept as a record by the identification authority along with relevant data about the human subject. A person wishing to enter a secure area has a sample taken from them by a security officer who authenticates the sample by IDs since a human sample is unable to be forged. However, biometrics is not always convenient to capture and verify, and requires 503022 CFP1703AU MMediaO9 I:\ELEC\CISRA\MMEDIA\MMedia49503022.doc -2more technological infrastructure. Further, biometric samples are considered to be intrusive to the subject and are not intuitively comprehended. Biometric analysis is also subject to a certain margin for error.

It is an object of the present invention to substantially overcome, or at least ameliorate, one or more disadvantages of existing arrangements.

Disclosure of the Invention According to one aspect of the present invention there is provided a system for identifying a subject, said system comprising: a first apparatus comprising: three dimensional video camera means for recording an image signal representing said subject; audio means for recording an audio signal from said subject; (first) processor means for processing said image and audio signals and applying a digital signature to said signals to form an encrypted composite u 15 signal; oo•• :-•-*recording means for recording said encrypted composite signal on a recording medium; and a second apparatus comprising: (second) processor means for accepting said recording medium, verifying said digital signature, and decoding said encrypted composite signal based on said digital signature to form a decoded signal; reproducing means for reproducing said image and audio signals from said decoded signal.

503022.doc -3- According to another aspect of the present invention there is provided a system for identifying a subject, said system comprising: a first apparatus comprising: camera means for recording an image signal representing said subject; audio means for recording an audio signal from said subject; (first) processor means for processing said image and audio signals and applying a digital signature to said signals to form an encrypted composite signal; recording means for recording said encrypted composite signal on a 10 recording medium; and *oo a second apparatus comprising: :(second) processor means for accepting said recording medium, verifying said digital signature, and decoding said encrypted composite signal based on said digital signature to form a decoded signal; 15 reproducing means for reproducing said image and audio signals from said decoded signal.

According to still another aspect of the present invention there is provided a method of identifying a subject, said method comprising the steps of: recording a three dimensional image signal of said subject; (ii) recording an audio signal from said subject; (iii) processing said image and audio signals to form a composite encoded signal; (iv) applying a digital signature to said composite encoded signal to form an encrypted composite signal; storing said encrypted composite encoded signal; 503022.doc -4- (vi) accessing said encrypted composite signal; (vii) verifying said digital signature; (viii) decoding said encrypted composite signal based on said digital signal to form a decoded signal; and (ix) reproducing said three dimensional image and said audio signal from said decoded signal.

According to still another aspect of the present invention there is provided a system for producing an image of a subject, said system comprising: camera means for recording a three dimensional image signal representing said subject; audio means for recording an audio signal from said subject; S' processor means for processing said image and audio signals and applying a 9 digital signature to said signals to form an encrypted composite signal; and recording means for recording said encrypted composite signal on an identification medium.

:..-°According to still another aspect of the present invention there is provided a 9 system for authenticating a recording medium, said system comprising: processor means for accepting said recording medium, reading an encrypted composite signal from said recording medium, verifying a digital signature decoding said encrypted composite signal based on said digital signature and outputting a three dimensional image signal and an audio signal; and reproducing means for reproducing said three dimensional image signal and said audio signal.

503022.doc According to still another aspect of the present invention there is provided a computer readable medium for storing a program for apparatus which processes data, said process comprising a method of identifying a subject, said program comprising: code for recording a three dimensional image signal of said subject; code for recording an audio signal from said subject; code for processing said image and audio signals to form a composite encoded signal; code for applying a digital signature to said composite encoded signal to form an encrypted composite signal; code for storing said encrypted composite signal; code for accessing said encrypted composite signal; code for verifying said digital signature; code for decoding said encrypted composite signal based on said digital signature to form a decoded signal; and code for reproducing said three dimensional image and said audio signal from said decoded signal.

Brief Description of the Drawings A number of preferred embodiments of the present invention will now be described with reference to the drawings, in which: Fig. 1 shows a system for capturing a video image of a human subject in accordance with the preferred embodiment; Fig. 2 shows a system for examining and authenticating the video image of the human subject, which was captured using the system of Fig. 1, in accordance with the preferred embodiment; 503022.doc Fig. 3 shows a flow chart of a method of capturing the video image of the human subject utilising the system of Fig. 1; Fig. 4 shows a flow chart of a method of examining and authenticating the video image of the human subject, which was captured using the system of Fig. 1; and Fig. 5 is a schematic block diagram of a general purpose computer which can be utilised in the system of Fig. 1.

Detailed Description including Best Mode Where reference is made in any one or more of the accompanying drawings to steps and/or features, which have the same reference numerals, those steps and/or features have for the purposes of this description the same function(s) or operation(s), unless the contrary intention appears.

The principles of the preferred embodiment described herein have general applicability to identification and authentication systems. However, for ease of *o.

V

V. 0 oo 503022.doc -6explanation, the steps of the preferred method are described with reference to human subject identification systems for the purposes of gaining entry into a secure area. It is not intended that the present invention be limited to the described method. For example, the invention may have application to identifying and authenticating automobiles entering a parking area or to the identification of animals being imported into a country.

The first embodiment is an identification system, which can capture a short identification three-dimensional (3D) video and audio clip of a subject as digital data.

The digital data can then be cryptographically signed to prevent forgery. At the point of entry to a secure area, the digital data can be replayed by a security officer controlling the S 10 entry point and compared to the person requesting entry. A 3D video is much harder than a still photograph to counterfeit because a subject's facial expressions, movements and voice contain substantially more data.

SFig. 1 shows a system 100 for capturing a video image of a human subject 105 in accordance with the preferred embodiment. The system comprises a 3D video camera 101 connected to microphone 107, which are used to capture a video and audio :representation of the human subject 105. Any known 3D video camera can be used in the system 100 and preferably the 3D video camera 101 would be under the control of an authority such as a consulate or embassy. The 3D video camera 101 preferably forms first image data for the right eye of a viewer and second image data for the left eye of a viewer, respectively. The method of forming first and second image data is well known per se and represents a 3D subject. The system 100 also comprises a computer system 102, connected to the 3D video camera 101, for processing the video and audio signals and converting the signals to a digital format. The computer system 102 comprises an encryption module (not illustrated), for example, a public key cryptosystem, which is used to sign the digital data with a secure key that is traceable to the video camera 101.

503022 CFP1703AU MMedia49 I:\ELEC\CISRA\MMEDIA\MMedia49\503022.doc -7- The computer system 102 preferably signs the digital data for the whole video clip. Any known public key cryptosystem can be used in the system 100 for providing the digital signature. A well-known technique for signing digital data will be detailed in the following paragraphs. The computer system 102 is connected to a recording means 109 for recording the signed digital data onto an identification medium 103. The identification medium 103 in accordance with the first embodiment is preferably an optical card.

In accordance with one embodiment, the computer system 102 can process the first image data or the second image data described above, selectively for applying a 10 digital signature to an image. Processing the first image data and the second image data selectively makes the provision of a digital signature more efficient.

cryptosystem works by processing a piece of digital data, which can be regarded as a sequence of bits, using the following known technique. Firstly, the bits comprising the digital data are summarised using a hash algorithm, sometimes known as a message digest algorithm, which is a data volume reduction technique that combines all of the bits to obtain a digital signature known as a "fingerprint" in such a way that o* substitution of any of the bits results in the generation of a different fingerprint. The "technique is probabilistic, such that when the number of bits in the sum can be made sufficiently large, for example, 1024 bits, it would take an infeasibly large number of sets of digital data to have a significant chance of two sets having the same fingerprint.

Furthermore, the algorithm chosen to convert between the original data and the fingerprint is unidirectional so that there is no way to discover in a feasible amount of time how to alter the original data while preserving the same fingerprint. An example of such a well-known algorithm is the MD5 hash algorithm. The fingerprint is encoded using a private key associated with the "sender". In the case of the preferred embodiment, 503022 CFP1703AU MMedia49 I:\ELEC\CISRA\MMEDIA\MMedia49503022.doc -8the camera 101 represents the sender. The fingerprint is appended digitally to the video clip and serves as a certification that the video clip was indeed generated by a particular camera. The fingerprint must be digitally attached in such a way that it cannot be detached from the video clip. This is simply accomplished by having a certificate which comprises the encoded fingerprint and also describes the total length of the video clip data, the starting bit number and the ending bit number of the portion of the data that is to be certified, and appending the certificate to the video clip data. This guards against a forger substituting an arbitrary length of video clip data fabricated so as to have the same checksum.

10 In public key encryption, a private key is generated at the same time as a public key in a unique pair. Messages encoded with the private key can be decoded only with the public key, and vice versa. In use, the sender keeps the private key confidential and makes public the public key. Knowledge of the public key does not reveal the private key. Thus a message that can be decoded with a given public key could only have been a.o.

generated by the sender possessing the corresponding private key, provided the sender has not disclosed his private key to any other party. In accordance with the preferred embodiment, the private key belongs to the camera and is embedded in the hardware in "such a way that it cannot be disclosed.

Upon reception of the video clip and the appended certificate, the viewing apparatus reverses the process. The video clip is summarised using the same hash algorithm to obtain a computed fingerprint. The certificate is decoded using the wellknown public key of the camera and the transmitted fingerprint is extracted. This is compared with the computed fingerprint and if the two are identical, then it can be asserted, with a very high degree of probability, that the video clip was indeed generated with that particular camera.

503022 CFP1703AU MMedia49 I:ELEC\CISRA\MMEDIA\MMedia49\503022.doc -9- Fig. 2 shows a system 200 for examining and authenticating the video image of the human subject 105, which was captured using the system 100 of Fig. 1, in accordance with the preferred embodiment. The system 200 comprises a playing means 203, which accepts the identification medium 103 and can play back the signed digital data on a viewing means 201. The viewing means 201 is preferably a pair of 3D viewing glasses, which are known per se. The playing means 203 can also read the certificate which has been appended to the digital data and verify that the signed digital data has not been altered after it was recorded, by using the technique described above. The playing means 203 uses a public key that matches the secure key of the video camera 101, to decode the 10 certificate. Preferably the playing means 203 would comprise a database of all the sees .*0:1 of 4* matching public keys to secure keys relevant to that playing means 203. Thus, a security officer at a secure entry point can view the signed digital data using the system 200 and :Cog.

compare the displayed image with the subject wishing to gain entry. The security officer can also be sure of the authenticity of the identification medium 103 since the digital signature has been verified by the playing means 203.

Fig. 3 shows a flow chart of a method of capturing the video image of the human subject 105 utilising the system 100 of Fig. 1. The method begins at step 301, where the "subject 105 to be recorded is placed in front of the 3D video camera 101 and asked to say a phrase into the microphone 107. For example, the subject 105 can say, "My name is Elvis!". The 3D video camera 101 preferably captures approximately 10 seconds of video and audio data. Preferably the 3D video camera 101 can pan in an arc around the subject 105 to allow a fuller capture of the subject's features. At the next step 303, the captured video and audio signals are processed in the computer system 102 to convert the signals to digital format. The process continues at step 305, where the encryption module signs the digital data with a fingerprint using a key that is traceable to the 3D video 503022 CFP1703AU MMedia49 I:ELEC\CISRA\MMEDIAMMedia49\53022.doc camera 101. In addition, the encryption module can ensure that the data is protected by a checksum so that the data cannot be tampered with or replaced on the identification medium 103 without discovery. At the next step 307, the signed digital data including the fingerprint and checksum information are recorded onto the identification medium 103 using the recording means 109. The signed digital data is preferably compressed using MPEG compression before being recorded onto the identification medium. The method concludes when all of the signed digital data has been recorded on the identification medium 102.

As discussed above, the system 100 can be under the control of an authority such as a consulate or embassy. For example, an Australian person wishing to enter France may go to the French Consulate, at Level 26, St Martin's Tower, Sydney, where a consular official would capture a ten second video and audio representation of the person, oooo utilising the system 100. A digital key used to sign the video and audio representation would be a secure key held by the French Consulate. The consular official can also take S 15 the details (eg. name, date of birth etc.) of the Australian person, which could also be recorded on a personal optical card along with the video and audio representation. The consular official would then give the person the personal optical card containing the recorded video and audio representation.

S•Fig. 4 shows a flow chart of a method of examining and authenticating the video image of the human subject 105, which was captured using the system 100 of Fig. 1, in accordance with the preferred embodiment. The method begins at step 401, where the subject 105 offers the identification medium 103 to a security officer controlling entry to a secure site that the subject 105 wishes to enter. At the next step 403, the security officer inserts the identification medium 103 into the playing means 203 and plays back the signed digital data which is observed on the viewing means 201. The playing means 203 503022 CFP1703AU MMediaO9 I:\ELEC\CISRA\MMEDIA\MMedia49\503022.doc -11decrypts the signed digital data using the matching public key to the secure key of the 3D video camera 101. The observed image can then be compared to the subject. At step 405, which is carried out in parallel to step 403, the playing means 203 reads the identification medium 103 and verifies the fingerprint and checksum information to ensure that the digital data has not been altered after being recorded.

The system 200, of the preferred embodiment, can be controlled by an authority such as a customs immigration agency. In keeping with the example discussed above, the French Immigration Authorities at 'Charles De Gaulle Airport' would control the system 200. The Australian person would present their personal optical card to the French immigration official upon landing in Paris. The immigration official would insert the card into the playing means 203 and play back the signed digital data, which they then observe on the viewing means 201. The playback machine 203 would have a database .i containing the matching public key to the secure key held by the French Consulate in Australia. The database of the playback machine 203 would preferably contain all the S 15 public keys that match the secure keys of cameras trusted by the French authorities. The immigration official can then compare the image to the subject. At the same time the 00 "playing means 203 verifies the digital signature to ensure that the digital data has not been altered.

The preferred embodiment provides a more convenient and secure system for subject identification, since a subject's facial expressions, movements and voice are difficult to impersonate. Further, the preferred embodiment provides a much richer representation of a subject than a mere photograph. The richer representation aids in identification and enables a better verification of a subject to be made. Still further, the method is not intrusive to a subject and is intuitively comprehensible. Finally, any 503022 CFP1703AU MMedia49 I:\ELEC\CISRA\MMEDIA\MMedia49\503022.doc -12margin for error in identification is greatly reduced since the digital signature ensures that the digital data has not been altered after being recorded.

The aforementioned preferred methods comprise a particular control flow. There are many other variants of the preferred methods which use different control flows without departing the spirit or scope of the invention. Furthennrmore more of the steps of the preferred methods may be performed in parallel rather sequentially.

The computer system 102 is preferably a conventional general-purpose computer system 500, such as that shown in Fig. 5 wherein the processes of Fig. 3 may be implemented as software, such as an application program executing within the computer system 500. In particular, the steps of method of Fig. 3 are effected by instructions in the software that are carried out by the computer. The software may be divided into two separate parts; one part for carrying out the method; and another part to manage the user interface between the latter and the user. The software may be stored in a computer readable medium, including the storage devices described below, for example. The software is loaded into the computer from the computer readable medium, and then executed by the computer. A computer readable medium having such software or computer program recorded on it is a computer program product. The use of the computer program product in the computer preferably effects an advantageous apparatus •for processing the video and audio signals and converting the signals to a digital format in accordance with the embodiments of the invention.

The computer system 500 comprises a computer module 501, input devices such as a keyboard 502 and mouse 503, output devices including a printer 515 and a display device 514. A Modulator-Demodulator (Modem) transceiver device 516 is used by the computer module 501 for communicating to and from a communications network 520, for example connectable via a telephone line 521 or other functional medium. The modem 503022 CFP1703AU MMedia49 I:\ELEC\CISRA\MMEDIA\MMedia49\503022.doc -13- 516 can be used to obtain access to the Internet, and other network systems, such as a Local Area Network (LAN) or a Wide Area Network (WAN).

The computer module 501 typically comprises at least one processor unit 505, a memory unit 506, for example formed from semiconductor random access memory (RAM) and read only memory (ROM), input/output interfaces including a video interface 507, and an I/O interface 513 for the keyboard 502 and mouse 503 and optionally a joystick (not illustrated), and an interface 508 for the modem 516. A storage device 509 is provided and typically comprises a hard disk drive 510 and a floppy disk drive 511. A magnetic tape drive (not illustrated) may also be used. A CD-ROM drive 512 is typically provided as a non-volatile source of data. The components 505 to 513 of •the computer module 501, typically communicate via an interconnected bus 504 and in a manner which results in a conventional mode of operation of the computer system 500 known to those in the relevant art. Examples of computers on which the embodiments can be practised include IBM-PC's and compatibles, Sun Sparcstations or alike computer S 15 systems evolved therefrom.

Typically, the application program of the preferred embodiment is resident on :the hard disk drive 510 and read and controlled in its execution by the processor 505.

Intermediate storage of the program and any data fetched from the network 520 may be -•accomplished using the semiconductor memory 506, possibly in concert with the hard disk drive 510. In some instances, the application program may be supplied to the user encoded on a CD-ROM or floppy disk and read via the corresponding drive 512 or 511, or alternatively may be read by the user from the network 520 via the modem device 516.

Still further, the software can also be loaded into the computer system 500 from other computer readable medium including magnetic tape, a ROM or integrated circuit, a magneto-optical disk, a radio or infra-red transmission channel between the computer 503022 CFP1703AU W~edia49 I:\ELEC\CISRA\MMEDIA\MMedia49\503022.doc -14module 501 and another device, a computer readable card such as a PCMCIA card, and the Internet and Intranets including email transmissions and information recorded on websites and the like. The foregoing is merely exemplary of relevant computer readable mediums. Other computer readable mediums may be practiced without departing from the scope and spirit of the invention.

The method of Fig. 3 may alternatively be implemented in dedicated hardware such as one or more integrated circuits performing the functions or sub functions of Fig.

3. Such dedicated hardware may include graphic processors, digital signal processors, or one or more microprocessors and associated memories.

The foregoing describes only one embodiment of the present invention, and modifications and/or changes can be made thereto without departing from the scope and spirit of the invention as be illustrative and not restrictive. For example, the identification :medium 103 can be a flashcard. Further, the identification medium 103 can be a CD-

SROM.

15 In the context of this specification, the word "comprising" means "including principally but not necessarily solely" or "having" or "including" and not "consisting only of'. Variations of the word comprising, such as "comprise" and "comprises" have corresponding meanings.

503022 CFP1703AU MMediaO9 I:ELEC\CIRA\MMEDIA\MMedia49\503022.doc

Claims (4)

1. A system for identifying a subject, said system comprising: a first apparatus comprising: three dimensional video camera means for recording an image signal representing said subject; audio means for recording an audio signal from said subject; (first) processor means for processing said image and audio signals and applying a digital signature to said signals to form an encrypted composite signal; .recording means for recording said encrypted composite signal on a o*°a. recording medium; and a second apparatus comprising: (second) processor means for accepting said recording medium, 15 verifying said digital signature, and decoding said encrypted composite signal based on said digital signature to form a decoded signal; i., :reproducing means for reproducing said image and audio signals from :said decoded signal.

2. The system according to claim I, wherein said digital signature is dependent on a key.

3. The system according to any one of the preceding claims, wherein said recording medium is an optical card.

503022.doc -16-

4. The system according to any one of claims 1 or 2, wherein said recording medium is a flashcard. The system according to any one of claims 1 or 2, wherein said recording medium is a compact read only memory disk (CD ROM). 6. The system according to any one of the preceding claims, wherein said (first) processor means is configured to convert said video and audio signals to digital signals. 7. The system according to any one of the preceding claims, wherein said camera •0 0 pans in an arc around said subject. @0 0 0o S* 8. The system according to any one of the preceding claims, wherein said signed digital data is compressed before being recorded on said recording medium. 9. The system according to any one of the preceding claims, wherein said (second) 0go• processor means comprises a plurality of public keys. The system according to any one of the preceding claims, wherein said display means is a pair of viewing goggles. 11. The system according to any one of the preceding claims, wherein said camera captures a sequence of images. S12. A system for identifying a subject, said system comprising: 503022.doc -17- a first apparatus comprising: camera means for recording an image signal representing said subject; audio means for recording an audio signal from said subject; (first) processor means for processing said image and audio signals and applying a digital signature to said signals to form an encrypted composite signal; recording means for recording said encrypted composite signal on a recording medium; and a second apparatus comprising: (second) processor means for accepting said recording medium, verifying said digital signature, and decoding said encrypted composite signal based on said digital signature to form a decoded signal; reproducing means for reproducing said image and audio signals from said decoded signal. 13. The system according to claim 12, wherein said digital signature is dependent on 0 *0o* a key. 0* 14. The system according to any one of claims 12 or 13, wherein said recording medium is an optical card. The system according to any one of claims 12 or 13, wherein said recording medium is a flashcard. 503022.doc -18- 16. The system according to any one of claims 12 or 15, wherein said recording medium is a compact read only memory disk (CD ROM). 17. The system according to any one of claims 12 to 16, wherein said camera is a three dimensional video camera. 18. The system according to claim 17, wherein said (first) processor means is configured to convert said video and audio signals to digital signals. 19. The system according to any one of claims 12 to 16, wherein said camera is a digital camera. S. 20. The system according to any one of claims 12 to 19, wherein said camera is a still camera. o. o. 21. The system according to any one of claims 12 to 20, wherein said camera pans in S S555 S an arc around said subject. 22. The system according to any one of claims 12 to 21, wherein said signed digital data is compressed before being recorded on said recording medium. 23. The system according to any one of claims 12 to 22, wherein said (second) processor means comprises a plurality of public keys. 503022.doc -19- 24. The system according to any one of claims 12 to 23, wherein said display means is a pair of viewing goggles. The system according to any one of claims 12 to 24, wherein said camera captures a sequence of images. 26. A method of identifying a subject, said method comprising the steps of: recording a three dimensional image signal of said subject; (ii) recording an audio signal from said subject; (iii) processing said image and audio signals to form a composite encoded signal; e (iv) applying a digital signature to said composite encoded signal to form an encrypted composite signal; storing said encrypted composite encoded signal; (vi) accessing said encrypted composite signal; (vii) verifying said digital signature; (viii) decoding said encrypted composite signal based on said digital signal to form a decoded signal; and (ix) reproducing said three dimensional image and said audio signal from said decoded signal. 29. The method according to claim 26, wherein said digital signature is dependent on a key. 503022.doc The method according to any one of claims 26 to 29, wherein said three dimensional image signal is a video signal. 31. The method according to claim 30, wherein said step (iii) further comprises a sub-step of converting said video and audio signals to digital signals. 32. The method according to any one of claims 26 to 31, wherein said encrypted composite encoded signal is compressed before being stored. 10 33. The method according to any one of claims 26 to 32, wherein a sequence of images is recorded. 34. A system for producing an image of a subject, said system comprising: camera means for recording a three dimensional image signal representing said so so 15 subject; audio means for recording an audio signal from said subject; 00 oo processor means for processing said image and audio signals and applying a 0 0 digital signature to said signals to form an encrypted composite signal; and .0.0 *0 0 recording means for recording said encrypted composite signal on an identification medium. The system according to claim 38, wherein said camera is a three dimensional video camera. 503022.doc -21 36. The system according to claim 35, wherein said processor means is configured to convert said video and audio signals to digital signals. 37. A system for authenticating a recording medium, said system comprising: processor means for accepting said recording medium, reading an encrypted composite signal from said recording medium, verifying a digital signature, decoding said encrypted composite signal based on said digital signature and outputting a three dimensional image signal and an audio signal; and reproducing means for reproducing said three dimensional image signal and said 10 audio signal. o 40. A computer readable medium for storing a program for apparatus which processes data, said process comprising a method of identifying a subject, said program comprising: 15 code for recording a three dimensional image signal of said subject; 5559 •.code for recording an audio signal from said subject; °ooo code for processing said image and audio signals to form a composite encoded signal; code for applying a digital signature to said composite encoded signal to form an encrypted composite signal; code for storing said encrypted composite signal; code for accessing said encrypted composite signal; code for verifying said digital signature; code for decoding said encrypted composite signal based on said digital I4, gnature to form a decoded signal; and 503022.doc -22- code for reproducing said three dimensional image and said audio signal from said decoded signal. 41. A system for identifying a subject, substantially as herein described with reference to the accompanying drawings. Dated this Fourteenth Day of March 2002 Canon Kabushiki Kaisha Patent Attorneys for the Applicant SPRUSON&FERGUSON 0*0 i. p *PP* o•* ooo* 503022.doc