| 摘要 |
A method for protecting a portable card, provided with at least a crypto algorithm for enciphering data and/or authenticating the card, against deriving the secret key used from statistical analysis of its information leaking away to the outside world in the event of cryptographic operations, such as power-consumption data, electromagnetic radiation and the like. The card is provided with at least a shift register having a linear and a non- linear feedback funtion for creating cryptographic algorithms. An algorithm is applied to the card, which is constructed in such a manner that the collecti on of values of recorded leak-information signals is resistant to deriving the secret key from statistical analysis of said values. Advantageously, after t he key has been loaded into the shift register, the shift register clocks on, using at least the linear-feedback function. A suitable alternative is loadi ng only the key into the shift register in the event of a fixed content of the shift register.
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