Method of securely modifying data on a smart card
AssigneeKoninklijke PTT Nederland N.V.
InventorsMichel Marco Paul Drupsteen, Frank Muller
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Abstract
A method of securely transferring data, such as program data, to a smart card (1) is disclosed. In order to be applicable in non-secure environments, the method of the invention involves a one-way authentication mechanism, comprising the use of a series of interrelated authentication values (R0, R1, R2, . . . ). Further security is achieved by using commands (INIT, TRAN) which are each provided with an authentication code (MAC0, MAC1, . . . ). In order to transfer data only to selected cards, the card may accept transfer commands only if a card profile (CP) matches a distribution profile (DP).
Claims12
A method of securely modifying data in a smart card (1), the method comprising the steps of:
- producing an initiation command (INIT) comprising an initial authentication value (R0) and producing an initial authentication code (MAC0) based on the command and the initial value (R0),
- producing at least one transfer command (TRAN) comprising data (DATA) to be transferred and producing a subsequent authentication code (MAC1, MAC2, . . . ) based on both the command (TRAN) and a subsequent authentication value (R1, R2, . . . ) derived from the initial value (R0),
- transferring the commands and their authentication codes thus produced to the smart card (1),
- authenticating the commands in the smart card (1) by checking the authentication codes (MAC0, MAC1, . . . ) and checking the subsequent authentication values (R1, . . . ) derived from the initial value (R0), and
- storing the transferred data (DATA) in the card.
Dependencies are inferred from the claim text.