高效的身份基多用户全同态加密方案

针对传统的身份基全同态加密（IBFHE）方案无法对不同身份标识（ID）下的密文进行同态运算的问题，提出一个基于误差学习（LWE）问题的分层身份基多用户全同态加密方案。该方案利用Clear等（CLEAR M，McGOLDRICK C.Multi-identity and multi-key leveled FHE from learning with errors.Proceedings of the 2015 Annual Cryptology Conference，LNCS 9216.Berlin：Springer，2015：630-656）在2015年提出的身份基多用户全同态加密方案（CM15]方案）的转化机制，结合Cash等（CASH D，HOFHEINZ D，KILTZ E，et al.Bonsai trees，or how to delegate a lattice basis.Proceedings of the 2010 Annual International Conference on the Theory and Applications of Cryptographic Techniques，LNCS 6110.Berlin：Springer，2010：523-552）在2010年提出的身份基加密（IBE）方案（CHKP10]方案），实现了不同身份标识下的密文同态运算，应用前景更加广阔，在随机预言机模型下为基于身份匿名的选择明文攻击下的不可区分性（IND-ID-CPA）安全。与CM15]方案相比，该方案在公钥规模、私钥规模、密文尺寸、分层性质和密钥更新周期方面都具有优势。

Efficient identity-based multi-identity fully homomorphic encryption scheme

Focusing on the issue that the traditional Identity-Based Fully Homomorphic Encryption scheme (IBFHE) cannot perform homomorphic operations on ciphertexts under different IDentities (ID), a hierarchical identity-based multi-identity fully homomorphic encryption scheme based on Learning With Error (LWE) problem was proposed. In the proposed scheme, the transformation mechanism of identity-based multi-identity homomorphic encryption scheme (CM15] scheme) proposed by Clear et al. (CLEAR M, McGOLDRICK C. Multi-identity and multi-key leveled FHE from learning with errors. Proceedings of the 2015 Annual Cryptology Conference, LNCS 9216. Berlin:Springer, 2015:630-656) in 2015 was combined with Identity-Based Encryption (IBE) scheme proposed by Cash et al. (CASH D, HOFHEINZ D, KILTZ E, et al. Bonsai trees, or how to delegate a lattice basis. Proceedings of the 2010 Annual International Conference on the Theory and Applications of Cryptographic Techniques, LNCS 6110. Berlin:Springer, 2010:523-552) in 2010 (CHKP10] scheme), guranteeing IND-ID-CPA (INDistinguishability of IDentity-based encryption under Chosen-Plaintext Attack) security in the random oracle model and realizing ciphertext homomorphic operation under different identities, so the application of this scheme was more promising. Compared withCM15] scheme, the proposed scheme has advantages in terms of public key scale, private key scale, ciphertext size, and hierarchical properties, and has a wide application prospect.