MESSAGE ENCODING METHOD AND DECIPHERING DEVICE

摘要

PROBLEM TO BE SOLVED: To make the determination of a secret key through a deciphering action more complicated by adding a random bit pattern to a first partial key and coupling this bit pattern and an Euler's phi function applied to a second partial key so as not to affect the final result of the power. SOLUTION: A first partial key (e) and a second partial key N are stored in a memory 20 and these keys (e) and N are supplied through a connection means 50 to a processor 10. Then, a message is encoded at a deciphering device 1 based on a disclosed key method using the power of the message to be encoded due to the first partial key (e) with the second partial key N as a modulus. In this case, a bit pattern (r) generated by a random number generator 30 is added to the first partial key (e) and this bit pattern and the Euler'sΦfunction applied to the second partial key N are coupled so as not to affect the final result of the power. Thus, a different exponent per execution of deciphering is used and this exponent can not be deciphered.