Patent EA-002994-B1 (EA)
Title: Method for indivisibly modifying a plurality of sites in a microcircuit card non volatile memory, in particular a contactless card
Inventor: DIDIER STEPHANE
IPC: G06F21/64
Filed: 1999-04-09
Abstract: 1. A method for indivisibly modifying non volatile memory in a microcircuit card, in particular, a contactless card according to which the card is temporarily connected to a terminal while a transaction is being executed, in particular teleticketing transaction, wherein the transaction comprising the application by the terminal to the card of a plurality of modification commands each comprising at least an operation for posting, in the card memory, a respective information indicated by the modification command, the different data being thus posted mutually interdependent, characterized in that said method comprises the following steps executed by the card: a) on receiving from the terminal the corresponding respective modification commands, modifying the card memory content by provisional posting in the card memory each of said interdependent data without losing previous values corresponding to said data, then b) finalising said modifications, either by confirming all of them, or by denying them such that for subsequent operations the commands executed at step a) are either all taken into account, or are all null and void. 2. The method according to claim 1, characterized in that in case of confirmation at step b) a flag confirming proper execution is posted in the card memory, and when the card later receives the command for reading or modifying at least one data element posted at step a) or corresponding to its value, the card examines the flag condition and if it is not posted the card ignores or erases executed earlier at step a) and execute a command based on said previous values corresponding to the data elements. 3. The method according to claim 2, characterized in that when examining the flag condition by a card and detecting that it is posted the card executes operations of copying conditional posts executed at step a). 4. The method according to one of claims 1 or 2, characterized in that the card is adapted for functioning in two modes, namely: in in-session mode at which the posts are introduced by executing steps a) and b), and  in out-session mode at which the posts are not confirmed for steps a) and b). 5. The method according to any of claims 1 t0 4, characterized in that comprises combining a function of authentification with the function of finalization of step b), in case of unsuccessful authentification all said modifications are rejected at step b). 6. The method according to claim 5, characterized in that said authentification is operated by a card authentificating the terminal and/or data which are exchanged with the card, wherein the card controls a cryptographic certificate produced by the terminal and transmitted to the card confirm modifications introduced at step b), only in case if the certificate is acknowledged correct. 7. The method according to claim 6, characterized in that the card is adapted for functioning in two modes, namely: in in-session mode at which the posts are introduced by executing steps a) and b), and  in out-session mode at which the posts are not confirmed for steps a) and b) and that when the card receives the command for modification of the memory content from the terminal, including verification of said cryptographic certificate, said verification is performed when receiving command in out-session and not performed when receiving command in in-session. 8. The method according to claim 5, characterized in that said authentification is operated by a card authentificating the terminal and/or data which are exchanged with the card, wherein the card produces and transmits to the terminal a cryptographic certificate in a conditional manner only when modifications are confirmed at step b). 9. The method according to claim 1, characterized in that the card is adapted for functioning in two modes, namely: in in-session mode at which the posts are introduced by executing steps a) and b), and  in out-session mode at which the posts are not confirmed for steps a) and b) and that when the card receives from the terminal the command for modification of the memory content, including production of cryptographic certificate, said production is performed when receiving command in out-session and not performed when receiving command in in-session. 10. The method according to one of claims 1 or 2, characterized in that when the card receives the command for modification of the memory content from the terminal, including production a plurality of cryptographic certificates, said certificates store at step b) and then transmit together to the terminal, when said modifications are confirmed at step b). 11. The method according to claim 1, characterized in that the card is adapted for functioning in two modes, namely: in in-session mode at which the posts are introduced by executing steps a) and b), and  in out-session mode at which the posts are not confirmed for steps a) and b) and that  at least some of commands which can be executed at step b) comprise optional inhibition attribute and if the card executes said command in in-session mode at step b), then modifications operated by said command remain effective independently of the result of step b). 12. The method according to one of claims 1 or 2, characterized in that after the step b) and after confirmation said modifications d) execution by the terminal its function after said confirmation by the card, and e) in case of the proper execution of said function by the terminal, information of ratification is recorded in the card accessible for reading. 13. The method according to claim 1, characterized in that the command for recording at step d) is an implicit information, any command received by the card after step b) is interpreted as a command for recording information to the card of the ratification.