基于身份的无对密文等值测试公钥加密方案

公钥加密等值测试技术可以判断云服务器中使用了不同公钥加密的密文所对应的明文是否相同。基于传统PKI体系的密文等值测试公钥加密方案大多数是借助双线性对来实现，计算繁琐、效率偏低，同时随着用户数量增加，大量证书的生成、申请、颁发和撤销等工作愈发繁重，给系统的维护工作和可持续工作带来了挑战。针对该问题，提出了基于身份的无对密文等值测试公钥加密方案PF-IBEET，通过明文信息构造出的2点确定一条直线，利用直线实现加密、解密、授权和等值测试过程，摆脱了双线性对的限制，计算效率得到提高，同时PF-IBEET方案是在身份密码体制下构建的，解决了传统PKI体系中复杂的证书管理问题。在随机预言模型下,基于CDH和DDH数学困难问题，证明了PF-IBEET方案满足OW-ID-CCA和IND-ID-CCA安全。

Pairing-free identity-based public keyencryption with equality test

Public key encryption with equality test can determine whether the plaintexts of ciphertexts encrypted with different public keys in the cloud server are identical. Most of the public key encryption schemes with equality test based on traditional PKI system are implemented by bilinear pairs, whose computation is cumbersome and inefficient. At the same time, with the increase in the number of users, the generation, application, issuance and revocation of a large number of certificates become more and more onerous, which brings challenges to the maintenance and sustainable work of the system. To address this problem, this paper proposes a pairing-free identity-based public key encryption with equality test. The scheme determines a straight line through the two points constructed from the plaintext information, and uses the straight line to implement the encryption, decryption, authorization and equality test processes, which gets rid of the restriction of bilinear pairs and improves the computational efficiency. Meanwhile, the scheme is constructed based on the identity cryptosystem, which solves the complex certificate management problem in the traditional PKI system. Under the CDH and DDH assumptions in the random oracle model, the proposed scheme is capable to achieve the security of OW-ID-CCA and IND-ID-CCA.