Abstract: A process for managing an electronic transaction with a trader by use of a microprocessor chip card and of a reading terminal able to interact with the card. The card performs a first comparison where it compares a transaction amount with a first threshold value and instigates a bearer authentication procedure when this amount is above the first threshold. When the amount of the transaction is below the first threshold, the chip card performs a second comparison where it compares with a second threshold value an incremented value of a first counter. The first counter being an aggregate of small amounts counter and being successively incremented by values of amounts of transaction in cases where the amounts are below the first threshold. A procedure for authenticating the bearer of the card is instigated by the card depending on the result of this second comparison.

Abstract: The transaction is made between an object and a terminal. According to the invention, an authentication value is inserted in the object which is a digital signature appearing on an identifier of the object. Each object also has a diversified key created from a base key diversified by the identifier. The terminal can thus authenticate the identifier and check that the debit has actually been made. Application to electronic payment.

Abstract: Method for carrying out an electronic transaction using several signatures. In the present invention, entities (or actors) are spread over a communication network and share keys. A message is encapsulated inside several cryptograms, and intermediate entities progressively decapsulate the cryptograms that they receive. The invention is applicable to all electronic transactions, in particular to “electronic wallet” applications.

Abstract: A process for managing an electronic transaction with a trader by use of a microprocessor chip card and of a reading terminal able to interact with the card. The card performs a first comparison where it compares a transaction amount with a first threshold value and instigates a bearer authentication procedure when this amount is above the first threshold. When the amount of the transaction is below the first threshold, the chip card performs a second comparison where it compares with a second threshold value an incremented value of a first counter. The first counter being an aggregate of small amounts counter and being successively incremented by values of amounts of transaction in cases where the amounts are below the first threshold. A procedure for authenticating the bearer of the card is instigated by the card depending on the result of this second comparison.

Abstract: A method for making a telecommunication terminal secure when it is connected to a terminal user identification module. The method including execution of a matching procedure in which the terminal transmits terminal identification information to the identification module connected to the terminal, and the identification module compares the identification information received from the terminal with terminal identification information stored in a memory, transmits the result of the comparison to the terminal, and if the identification information stored by the identification module corresponds to the information for the terminal, it sets an internal matching indicator (LOCK) indicating that the terminal has been identified by the identification module.

Abstract: A method for performing electronic transactions between a card, a service provider having at least one terminal configured to accept the card and a centralized system configured to be connected to the terminal. The terminal transmits to the card a parameter M including the sum of the transaction and its identity. The card produces two signatures, a first signature (z) depending on a secret debit key (k) and on the parameter (M), this first signature being a proof that the card balance has been debited; and a second signature (y) depending on the first signature (z), the second signature being produced either by an RSA algorithm or by an interactive algorithm. The terminal checks the second signature (y) but not the first one because it is unable to recover the secret debit key (k). The terminal stores the different first signatures (proofs) (z) and the parameters (M) for the different transactions. The centralized system can collect the first signatures and the parameters.

Abstract: A process for exchange of rights between microprocessor cards, wherein multiple keys (K1, K2, . . . ) and varied keys (Ka5, Kb3) are used. A card to be debited calculates a voucher with varied key (Ka5) that the card to be credited reconstitutes. The process has application to electronic payment.

Abstract: Electronic payment method wherein a memory is used with two zones of equal capacity, a payment zone and a reloading zone. A stop-bit equal to "0" is written in the payment zone. A first payment of a certain amount is obtained by counting an amount equal to the payment of "1's" in the payment zone starting from the first bit in the memory. A "0" is written accordingly. A second payment of any other amount is obtained by counting another amount of "1's" equal to the new payment starting from the preceeding "0" and a "0" is written and so on until the rank of the bit to be written as "0" in the payment zone overshoots the rank of the stop-bit in the reloading zone. For a reloading operation a "0" is written in the reloading zone for all bits having the same rank as the "0" bits in the payment zone and a new stop-bit is determined and this is set equal to "0" by writing in the reloading zone.