Re-encryption system, re-encryption method and re-encryption program

摘要

Provided is a re-encryption system. The re-encryption system includes a replacement key generation unit. The replacement key generation unit receives a master key owned by a manager, an allowable decryptor set before change, and an allowable decryptor set after change. The re-encryption system generates and outputs a replacement key to convert a ciphertext which can be decrypted with a secret key of a decryptor belonging to the allowable decryptor set before change to a ciphertext which can be decrypted with a secret key of a decryptor belonging to the allowable decryptor set after change.

主权项

1. A re-encryption system comprising:
a replacement key generation unit configured to:
receive a master key owned by a manager, an allowable decryptor set before change, and an allowable decryptor set after change,generate and output a replacement key to convert a ciphertext which can be decrypted with a secret key of a decryptor belonging to the allowable decryptor set before change to a ciphertext which can be decrypted with a secret key of a decryptor belonging to the allowable decryptor set after change, andgenerate a new master key and update information used in generation of the secret key of the decryptor belonging to the allowable decryptor set after change.