ENCRYPTION DEVICE, DECRYPTION DEVICE, CRYPTOGRAPHY VERIFYING DEVICE, ENCRYPTION METHOD, DECRYPTION METHOD AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide an encryption technique which can reduce the size of data while restraining increase in processing time in a public key cryptosystem, which has basis of safety on discrete logarithm problem on a sub-group of a multiplication group.;SOLUTION: An encryption device compresses some cryptography components of the respective cryptography components of a cryptography (c1, c2) and generates the other cryptography components at the same time. Meanwhile, a decryption device expands the compressed cryptography components of the respective cryptography components of the cryptography (c1, c2) and performs various operations such as exponentiation and multiplication using the non-compressed cryptography components or already expanded cryptography components and a private key at the same time to thereby obtain a plaintext.;COPYRIGHT: (C)2010,JPO&INPIT