Identity-based proxy re-encryption scheme from RLWE assumption with ciphertext evolution

Proxy re-encryption (PRE) allows users to transfer decryption rights to the data requester via proxy. Due to the current PRE schemes from lattice (LPRE) cannot fulfill chosen-ciphertext attack (CCA) security, an identity-based PRE (IB-PRE) scheme from learning with errors over ring (RLWE) assumption with ciphertext evolution (IB-LPRE-CE) was proposed. IB-LPRE-CE generates the private key using the preimage sampling algorithm (SamplePre) and completes the ciphertext delegation using the re-encryption algorithm. In addition, for the problem of ciphertext delegation change caused by the long-term secret key update, the idea of PRE is used to complete ciphertext evolution and the modification of ciphertext delegation, which improves the efficiency of secure data sharing. In terms of security, IB-LPRE-CE is CCA security based on RLWE assumption. Compared with the current LPRE schemes, IB-LPRE-CE offers greater security and improves the computational efficiency of the encryption algorithm. © 2023, Beijing University of Posts and Telecommunications. All rights reserved.