PUBLIC-KEY ENCRYPTED COMMUNICATION SYSTEM, PUBLIC-KEY ENCRYPTED COMMUNICATION METHOD, AND PUBLIC-KEY ENCRYPTED COMMUNICATION PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide public-key encrypted communication whose public key is easy and safe to manage even when a key pair of a public key and a secret key are updated at any time. SOLUTION: A public-key encrypted communication system includes a transmitting terminal which transmits encryption data generated by encrypting plaintext data with a public key and a receiving terminal which receives the encryption data from the transmitting terminal and deencrypts the data with the secret key paired with the public key. Each time the key pair consisting of the public key and secret key are updated, the receiving terminal manages secret keys of a plurality of generations including the secret key of the newly updated key pair, receives encryption data encrypted with a public key of one of the generation to acquire a secret key from the managed secret keys of the plurality of generations, and deencrypts the encryption data. The transmitting terminal transmits encryption data generated by encrypting the plaintext data with an open key of one of the generations. COPYRIGHT: (C)2008,JPO&INPIT