Unforgeable identification device, identification device reader and method of identification

Abstract: Memory cards are cheap and contain memory means, but can be forged and duplicated easily. Smart-cards contain also a micro-processor and can be used for cryptographic purposes, but are much more expensive. The plastic support (14) of the card contains randomly distributed ferrite particles (11) (eg. small steel marbles, introduced into the plastic paste during the melting process). This random distribution of the particles is assumed to be impossible to control or influence during the process of fabrication. For personalizing a card, the issuing authority scans the plastic support of the card with a magnetic inductance detector, thereby reading the emplacement of the ferrite particles as a number p. Then the authority computes s = SIG(ID,p), where "SIG" denotes any secure public-key digital signature algorithm and ID the identification details of the card's owner. Finally, s and ID are recorded in the memory means (13) of the card. When such a card is inserted into a reader, the reader scans the plastic part of the card and reads the distribution characteristics as a number p. Then ID and s are retrieved from the card's memory means and the reader checks that s is the valid signature of {ID,p}.

Description: The invention relates to an unforgeable identification device, identification device reader and to a method of identification. Background Different kind of plastic cards are known. Memory cards are cheap and contain memory means, but can be forged and duplicated easily. Smart-cards contain also a microprocessor and can be used for cryptographic purposes, e.g. in pay TV applications and banking, but are much more expensive. US-A-4 094 462 discloses an unforgeable credit card including a diffraction grating stripe which has a distribution which can be represented by a unique number, wherein the diffraction grating cannot be controlled under production of said card but can be evaluated in a card reader. The card further contains a memory stripe for storing a customer number which is combined with said unique number to form a security information. Invention A device according to the preamble of claim 1 is known from US-A-4 094 462. It is one object of the invention to disclose a cheap and unforgeable memory card. This object is achieved by the identification device disclosed in claim 1. The inventive memory card is characterised in that once issued by an authority, the card is nearly impossible to copy and duplicate. This new memory card has significant cost advantages over microprocessor-based smart-cards. The process of fabrication of the new cards differs from that of standard cards in that small metal or ferrite particles (eg. steel marbles) are mixed with the plastic paste from which the plastic support of the card is to be produced. Each resulting card will therefore contain a different random distribution pattern of particles. This random distribution of the particles is assumed to be impossible to control or influence during the process of fabrication. A reader of the identification device is defined in claim 4. The reader is provided with magnetic inductance detectors (reader) that allow to read the distribution of particles as a number p and with a chip reader for reading the card's memory means. In order to personalize a card, the issuing authority does the following : 1. Establish the identity details ID of the card's owner; 2. Pick a card and read it's random pattern p; 3. Compute s = SIG(ID,p); 4. Record s and ID in the memory means of the card; 5. Give the card to the user. Here "SIG" stands for any secure public key digital signature scheme. The memory means are electronically protected. When a memory card is inserted into a verification reader, the reader will scan it and convert the random distribution of particles into the number p. Next, the verification reader will read s and ID from the card's memory means and will check that s is actually the signature of {ID,p} by performing SIG -1 . An identification system consisting of an identification device and a reader is disclosed in claim 6. A method of identification which utilizes the inventive identification device and reader is defined in claim 8. Drawings Preferred embodiments of the invention are described with reference to the accompanying drawings, which show in: Fig. 1 structure of an inventive memory card; Fig. 2 structure of an inventive reader for the memory card. Preferred embodiments In Fig. 1 buried ferrite particles 11 are distributed within the plastic support 14 of a memory card with standardized shape. This card contains a chip 13 with which data can be exchanged in a respective reader, e.g. contactless. At two sides of the card electronic scanner synchronisation marks 12 are arranged. In Fig. 2 the card is inserted in a reader (scanner). The reader includes electromagnetic scanning cells 22 for generating the distribution value p, e.g. an optical scanning synchronization head 23 and reading means (smart-card chip reader) 24 for at least the identity data ID and data s stored in the memory of the chip 13. ID, s, the distribution value p and possibly the password w are evaluated in a microprocessor 21 which can be a part of the reader device. One example of digital signature schemes is Rabin's signature scheme where n is an RSA modulus and s is defined by s = SIG(m) = m 1/2 mod n. The corresponding verification is done by checking that s 2 mod n = m. Optionally, one can improve the basic scheme by including also a user's password w. In such a case, the process of issuing a card and verifying it's validity becomes : 1. Establish the identity details ID of the card's owner. 2. Pick a card and read it's random pattern p. 3. Decide about a password w specific to the user. 4. Compute s = SIG(ID,p,w) 5. Record s and ID in the memory means of the card. 6. Give the card and w to the user. For verifying the validity of this card, the verification reader will proceed as before but will request from the user to key-in w. The SIG scheme can be one of the following or respective methods: Rabin's digital signature; RSA algorithm, Rivest, Shamir, Adelman, "A method for obtaining digital signatures and public-key cryptosystems", Communications of the ACM, Vol 21, No 2, pp 120-126, 1978); Data Signature Standard (DSS); El Gamal, "A public-key cryptosystem and a signature scheme based on the discrete logarithm", IEEE Transactions on Information Theory, vol. 31, No. 4, pp. 469-472, 1985; Fiat, Feige and Shamir, "Zero-Knowledge Proofs of Identity", Journal of Cryptology, vol 1, pp. 77-94. See also EP-A-0252499 and EP-A-0325238. For synchronizing the scanning of the ferrite particles (whatever the insertion speed of the card is), the card can be marked, e.g. at the boundaries, by a sequence of mechanical (embossed or holes) or optical marks. The marks are preferably detected optically by the reader and trigger the scanning of plastic band by band. The marks can also be based on electromagnetic detection techniques and the triggering of the scanning is done accordingly. Instead of a card any other kind of device or shape can be used, whereby the reader is adapted respectively. Identification shall also mean authentication.

Claims: Unforgeable plastic device including an area (14) in which detectable elements (11) have a distribution which can be represented by a value p, wherein said distribution cannot be controlled under production of said plastic device but can be evaluated in reader means (22), the device containing a memory chip (13) for storing at least identity data (ID) and data s = SIG(ID, p) corresponding to a digital signature scheme SIG which is a function of the identity data (ID) and p, characterised by: said detectable elements are magnetic particles (11), in particular steel or ferrite pellets, having a random distribution and being buried in and mixed with the plastic of the device; the digital signature scheme is public-key digital signature scheme; the memory means are of the type electronically protected. Device according to claim 1, wherein said scheme is further a function of a user-specific password. Device according to claim 1 or 2, which is marked (12) for scanning control, e.g. scanning speed and/or synchronisation, using a sequence of embossed marks or holes or optical marks. Identification device verification reader for an identification device according to any of claims 1 to 3, including detector means (22) for scanning said elements (11) in order to determine the value p, and including reading means (24) for reading at least said identity data (ID) and data s from the memory means of said identification device, characterised in that said detector means (22) is in particular a magnetic inductance reader, and that the verification reader checks whether s is actually the signature of {ID,p} by performing the inverse public-key digital signature scheme SIG -1 . Reader according to claim 4, including means (23) for evaluating said scanning control marks (12). Identification system, including an identification device according to any of claims 1 to 3 and an identification device verification reader according to claim 4 or 5. Method of identification using an identification device according to any of claims 1 to 3 and an identification device verification reader according to claim 4 or 5, including the following identification device issuing steps: collecting identity details ID of a user; reading p and computing s = SIG(ID, p), where SIG is a public-key digital signature scheme function; storing s and ID in memory means (in 13) of said identification device, and including the following identification steps: reading the identification device using an identification device verification reader, whereby value p is generated (22) and at least s and ID are read from said memory means (in 13); checking that s is actually the signature of ID and p concatenated by performing (21) the respective inverse public-key digital signature scheme function SIG -1 . Method according to claim 7, wherein in the issuing steps said public-key digital signature scheme s = SIG(ID, p, w) includes a password w specific to said user and that in the identification steps the user enters said password w, whereafter it is checked that s is actually the signature of ID, p and w concatenated. Method according to claim 7 or 8, wherein the reading of said identification device is synchronised using scanning control marks (12).

Inventors: FREMANTEAU PATRICE, NACCACHE DAVID, FREMANTEAU, PATRICE, NACCACHE, DAVID
Applicants: THOMSON MULTIMEDIA SA, THOMSON MULTIMEDIA
Application year: 1993
Main classification: G06K19
IPC codes: G07F7, G06K19