Hierarchical Identity-Based Conditional Proxy Re-encryption Scheme Based RLWE and NTRU Variant

IB-PRE can perform fine-grained access control on the user’s decryption rights based on the identity of the delegatee, while the proxy cannot obtain the identity information of the delegator and delegatee. The current identity-based proxy re-encryption scheme achieves the ciphertext conversion between users at the same level, while it does not further distinguish between different levels of user identity, which is not suitable for hierarchical user management system. This paper combines hierarchical identity encryption with proxy re-encryption, and uses RLWE encryption system and NTRU variant as the underlying encryption scheme. According to the difference of the key reversibility and the ciphertext share between the two systems, the control of the decryption authority of users’ different levels was realized. The transformed cipher text still satisfies the rules of higher level to decrypt lower level cipher, and constructs a unidirectionality, collusion resistant, and non-interactive hierarchical identity-based conditional proxy re-encryption scheme(HIB-CPRE), which is IND-sid-CPA security under the RLWE difficult assumption.