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多方云计算是同态加密体制的重要应用.作为近年来的研究热点,同态加密可以直接对密文操作,其结果解密后相当于对明文进行同样操作.但是一般的同态加密方案只能作用于同一密钥加密的密文,而在多方计算的环境中,要对属于不同参与方的、用不同公钥加密后的密文进行运算,现有的同态加密方案无法满足这种应用.本文从代理重加密的思想出发,结合同态加密方案构造了一个同态代理重加密方案,该方案解决了由不同公钥加密的密文无法进行同态计算的问题,从而可以支持多方云计算.通过使用支持加法、乘法同态操作的类同态加密方案,实现了一个支持多方云计算的同态代理重加密方案.最后,提出了多方云计算的安全需求,并分析了该方案的安全性.
Multi-party cloud computing is an important application of homomorphic encryption system. As a hot research field in recent years, homomorphic encryption can directly operate on ciphertext, and the result after decryption is equivalent to that of plaintext. However, the common homomorphic encryption scheme can only In the environment of multi-party computing, ciphertexts encrypted by different public keys belonging to different parties are to be operated, and the existing homomorphic encryption schemes can not satisfy this application In this paper, we proceed from the idea of re-encryption of proxies and construct a homomorphic agent re-encryption scheme based on the homomorphic encryption scheme. This scheme solves the problem that the ciphertexts encrypted by different public keys can not be computed homogeneously, A homomorphic agent re-encryption scheme that supports multi-party cloud computing is implemented by using a homomorphic encryption scheme that supports addition and multiplication.Finally, the security requirements of multi-party cloud computing are proposed and analyzed safety.