Proxy re-encryption is a new public key encryption system.Proxy re-encryption has a secure cipher conversion function.In proxy re-encryption,the proxy uses a proxy re-encryption key to convert the cipher-text encrypted by the delegator's public key to a cipher-text encrypted by the public key of the delegatee.At the same time,the proxy cannot obtain any plain-text information of the cipher-text in the process of cipher-text conversion.Since the concept of proxy re-encryption was put forward,it has been a hotspot in the field of cryptography and information security.In this paper,we study the proxy re-encryption system with special properties for different application scenarios.including:(1)Based on identity encryption and identity broadcast encryption,a cross system agent re-encryption scheme based on identity is proposed.In the proposed scheme,the proxy uses the re-encryption key to convert the ciphertext based on identity encryption into the ciphertext based on identity broadcast encryption.Firstly,the formal definition,security model and specific scheme of the scheme are given.Secondly,based on the General decisional Diffie-Hellman exponent hypothesis,the scheme is proved to be safe in the random Oracle model.Finally,the analysis shows that the proposed scheme has a small amount of computation in the encryption stage and the re-encryption key generation stage.(2)Combining the thought of priority proxy re-encryption and time control proxy re-encryption,a time controlled priority proxy re-encryption scheme is proposed.In the proposed scheme,the time server performs time control,and the proxy uses the re-encryption key to generate the next decrypted ciphertext in a given time.Firstly,the formal definition of the scheme,the security model and the concrete scheme are given.Secondly,based on the assumption of 3-weakly determinant bilinear Diffe-Hellman inversion,it is proved that the scheme is safe in the random Oracle model.Finally,the analysis shows that the proposed scheme has the performance of time control. |