基于NTRU的多密钥同态代理重加密方案及其应用

为了提高同态加密算法在多用户云计算场景下的实用性,构造了一个基于NTRU的多密钥同态代理重加密方案.首先利用密文扩张思想提出了一种新的NTRU型多密钥同态密文形式,并基于此设计了相应的同态运算和重线性化过程,从而形成一个支持分布式解密的NTRU型多密钥同态加密方案;然后借助于密钥交换思想设计了重加密密钥和重加密过程,将...

Multi-key homomorphic proxy re-encryption scheme based on NTRU and its application

To improve the practicability of homomorphic encryption in the application of multi-user cloud computing,a NTRU-based multi-key homomorphic proxy re-encryption(MKH-PRE)scheme was constructed.Firstly,a new form of NTRU-based multi-key ciphertext was proposed based on the idea of ciphertext extension,and the corresponding homomorphic operations and relinearization procedure were designed on the basis of this new ciphertext form,so that a NTRU-based multi-key homomorphic encryption(MKHE)scheme which supported distributed decryption was constructed.Then,resorting to the idea of key switching,the re-encryption key and re-encryption procedure were put forward such that the functionality of proxy re-encryption(PRE)was integrated to this new NTRU-based MKHE scheme.The MKH-PRE scheme preserved the properties of MKHE and PRE,and had a better performance on the client side.The scheme was applied to the privacy-preserving problems in federated learning and an experiment of the application was carried out.The results demonstrate that the accuracy of learning is scarcely affected by the encryption procedure and the computational overhead of this MKH-PRE scheme is acceptable.