Efficient Cryptographic Protocols and Protection of Privacy

该项目有两个主要目标，旨在创建高效和安全的密码算法和协议，并提供在电子时代保护和增强隐私的手段。公钥密码(PKC)在现代安全通信和电子商务中占据核心地位。与PKC有关的一些基本问题具有重要的实践和理论意义。设ER是公钥加密函数。在合理的假设下，加密C=ER(M)保护了M的保密性。但是，对ER的攻击更为微妙。两种很难防范的威胁是选择密文攻击和延展性攻击。在后者中，对手可以用C*=ER(M+3)替换密文C，而不知道M是什么。为了保护加密免受这些危险的攻击，人们投入了大量深入的工作。所有普遍适用的解决方案都涉及到一般零知识证明(ZKP)的应用，因此，在多项式复杂性的原则下，需要过多的计算量。最近，PI能够通过不需要ZKP的更高效的算法来使任何语义安全的加密函数ER免受选择密文攻击和延展性攻击。一种新颖高效的明文知识证明协议起到了关键作用。所有这些方法都是通用的，因为它们适用于增强任何PK加密ER。这些新方法的进一步开发、应用和优化将继续进行。总体目标是为PKC及其应用程序实现一种全面、可证明安全和有效的方法。电子计算和互联网时代使个人隐私面临相当大的威胁。第二个重点是将密码学应用于这些隐私问题的解决。同样，重点是真正有效和可证明安全的解决方案，如安全和隐私保护访问包含个人数据的数据库，保护投票等交易的隐私。

The proposed project has two main thrusts, aimed at creating efficient and secure cryptographic algorithms and protocols, and providing means for protecting and enhancing privacy in the electronic era.Public-Key Cryptography (PKC) occupies a central position in modern secure communications and electronic commerce. There are a number of fundamental issues, of great practical and theoretical significance, related to PKC. Let ER be a public-key encryption function. Under reasonable assumptions an encryption C = ER(M) protects the secrecy of M. But there are more subtle attacks on ER. Two such threats which are very difficult to protect against, are the chosen ciphertext attack and the malleability attack. In the latter, and adversary may replace, say, the ciphertext C by C* = ER(M + 3), without knowing what M is. A considerable amount of profound work was invested in protecting encryptions against these dangerous attacks. All the generally applicable solutions involved application of general Zero Knowledge Proofs (ZKP) and consequently, while in principle of polynomial complexity, required an inordinate amount of computations. Recently the PI was able to immunize any semantically secure encryption function ER against chosen ciphertext attacks and malleability attacks by considerably more efficient algorithms which do not require ZKPs. A key role is played by a novel and efficient Proof of Plaintext Knowledge Protocol. All these methods are generic, in the sense that they apply to enhance any PK encryption ER. Further development, applications and optimization of these novel methods will be pursued. The overall objective is to achieve a comprehensive, provably secure, and efficient methodology for PKC and its applications.The electronic computing and Internet era exposes individuals to considerable threats to their privacy. The second thrust is aimed at bringing cryptography to bear on the solution of these privacy problems. Again, the emphasis is on truly efficient and provably secure solutions for such problems as secure and privacy preserving access to data bases containing personal data, privacy protection for transactions such as voting.