Authenticating method between a smart card and a terminal
First Claim
1. An authenticating method between a memory chip card having at least one counter and a terminal, comprising the following steps:
- (a) inserting the memory chip card into the terminal, (b) calculating, in the terminal, a secret code CSC1, according to a cryptographic function F of a number of variables comprising at least a code CSN identifying the memory chip card and the value of said counter, (c) authenticating the terminal by the card when the calculated secret code CSC1 is identical to a code CSC0 recorded in a memory of the card at the end of a previous authentication operation, (d) carrying out a desired transaction and modifying the value of said counter, (e) calculating, in the terminal, a new secret code CSC2 according to the cryptographic function F of the code CSN identifying the memory chip card and the new value of said counter, (f) updating the memory chip card for the next transaction by recording, in said memory, the new secret code CSC2 calculated by the operation (e).
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Accused Products
Abstract
The invention concerns a method enabling a smart card and a terminal whereto it is connected to authenticate each other. The invention is characterized in that at the end of each transaction the terminal calculates, from data representing the card at said transaction end, a secret code CSC2 which is recorded in a zone ZCSC with unprotected access in the card memory and an authentication certificate CA2 which is recorded in a zone ZCA with protected access of the memory by presenting a secret code CSC2. At the next transaction, the terminal calculates, by means of data contained in the card, a secret code and an authentication certificate which are compared to those previously recorded to perform authentication. The invention is applicable to smart cards.
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Citations
15 Claims
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1. An authenticating method between a memory chip card having at least one counter and a terminal, comprising the following steps:
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(a) inserting the memory chip card into the terminal, (b) calculating, in the terminal, a secret code CSC1, according to a cryptographic function F of a number of variables comprising at least a code CSN identifying the memory chip card and the value of said counter, (c) authenticating the terminal by the card when the calculated secret code CSC1 is identical to a code CSC0 recorded in a memory of the card at the end of a previous authentication operation, (d) carrying out a desired transaction and modifying the value of said counter, (e) calculating, in the terminal, a new secret code CSC2 according to the cryptographic function F of the code CSN identifying the memory chip card and the new value of said counter, (f) updating the memory chip card for the next transaction by recording, in said memory, the new secret code CSC2 calculated by the operation (e). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification