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Title: Practical privacy-preserving cryptographic protocols
Author: Ghadafi, Essam
ISNI:       0000 0004 2724 3811
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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The main aim of this thesis is to construct efficient protocols to help preserve privacy of users in today's digital world. We are interested in not only theoretically sound constructions but also those which could be deployed in practice. In particular, we are interested in constructions whose security could be based on standard assumptions rather than idealized ones which are hard to realize in real life. We look at different types of protocols which include: proof systems, blind signatures, group signatures and their applications. We investigate the security of such schemes and present new efficient constructions. We investigate the Groth-Sahai proof system and extend its applicability to new settings which were not possible before. We then provide some efficient implementations of different proof systems in different models and compare and contrast their efficiency. For such implementations, we present optimization techniques which make the proofs more efficient and hence more suitable for being deployed in practice. For instance, we provide details of how to efficiently batch verify such proofs which would significantly speed up the verification process. In particular, we look at the case of using proof systems for the problem of circuit satisfiability. We also look at another application of proof systems and consider the case of proving set membership with as little interaction as possible. We then turn our attention to different variants of signature schemes where we present a new efficient blind signature scheme whose security is proved under standard assumptions. We also look at group signatures and related primitives where we formally investigate the security of group blind signatures for which we present a formalized security model for the first time. This would promote more rigorous security proofs. We then present an efficient construction which has a number of desirable properties and yet its security does not rely on any non-standard assumptions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available