Identity-Based Unidirectional Collusion-Resistant Proxy Re-Encryption from U-LWE

Identity-based proxy re-encryption (IB-PRE) converts the ciphertext encrypted under the delegator's identity to the one encrypted under the delegatee's identity through a semitrusted proxy without leaking delegator's private key and the underlying plaintext. At present, the security of most IB-PRE schemes relies on the hardness of the discrete logarithm solution or large integer decomposition and cannot resist attacks of the quantum algorithms. The majority of the IB-PRE schemes over lattice are secure only in the random oracle model. Aiming at such problems, the paper constructs a secure IB-PRE scheme over lattice in the standard model. In the scheme, the underlying encryption scheme proposed by Gentry et al. in EUROCRYPT 2010 is adopted to reduce the storage space of ciphertext. The proposed scheme is unidirectional collusion-resistant multihop and anonymous, and it is semantically secure against selective identity and chosen plaintext attack based on Decisional Learning With Errors with uniformly distributed errors (D-U-LWE) hard problem in the standard model.