RE-ENCRYPTION KEY GENERATOR, RE-ENCRYPTION APPARATUS, ENCRYPTION APPARATUS, DECRYPTION APPARATUS, AND STORAGE MEDIUM

摘要

According to one embodiment, a re-encryption key generator which generates the re-encryption key based on the first private key, the second re-encryption key generation key, and a plurality of random numbers. The second re-encryption key generation key comprises a plurality of system-specific values and the second private key. The re-encryption key includes an exponent having a numerator portion and a denominator portion or a scalar having a numerator portion and a denominator portion. The numerator portion is in form of a linear coupling of the second private key on which at least one of a plurality of private values specifying relations between the system-specific values and the random numbers is allowed to act. The denominator portion is the first private key.