ENCRYPTION DEVICE, DECRYPTION DEVICE, ENCRYPTION METHOD, DECRYPTION METHOD, AND PROGRAM

摘要

An encryption device generates non-commutative matrices A1, A2 based on private data A and prime numbers p1, p2 (100), and operates the non-commutative matrices A1, A2 on vectors v i 1 , v i-1 2 (104). The encryption device performs non-linear transformation to transform the vectors v i 1 , v i 2 into bit sequences, and joins these to the bit sequences W1, W2 (106, 108). The encryption device repeats the operation of the non-convertible matrices and the non-linear transformation until the respective numbers of bits of the bit sequence W1 and the bit sequence W2 have reached a number of bits of a bit sequence expressing encryption target data (110). The encryption device derives a pseudo-random number bit sequence by computing the exclusive logical sum between the bit sequence W1 and the bit sequence W2 (112), and performs encryption using the pseudo-random number bit sequence. The encryption device is thereby able to increase the speed of encryption processing and to increase the cryptographic strength in cases in which the number of bits of the encryption target data is modifiable.