| 摘要 |
#CMT# #/CMT# The method involves subjecting a key (K) to a function (61) considering a selection value (M) e.g. selection bit or word of selected bits. Result of the function is completely or partly stored in registers (R0, R1). Content in the registers are read and subjected to another function (63) e.g. logical combination function, considering all or part of bits of the registers, when the key is called by an encryption/decryption algorithm (7). Result of combination is provided to an input of the algorithm, where the latter function is chosen such that the result of combination corresponds to the key. #CMT# : #/CMT# The function considering the selection value is a key bit distribution function or logical combination function. #CMT#USE : #/CMT# Method for protecting a key that is utilized in an encryption or decryption algorithm by an electronic circuit (claimed) of a chip card system. Can also be used for a pay TV system and an encrypted communication system. #CMT#ADVANTAGE : #/CMT# The method enables detecting unidirectional disturbances of the bits of the registers, and protecting the content of the registers against the unidirectional disturbances, without requiring any modification in the structure of processors of the chip card system. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a flow diagram illustrating a key protection method. K : Key M : Selection value R0, R1 : Registers 7 : Encryption/decryption algorithm 61, 63 : Functions. |
