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.
