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Conceptual Analysis and Extension of Zero-Knowledge Models & Definitions

Dousti, Mohammad Sadeq | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 47509 (19)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Jalili, Rasool
  7. Abstract:
  8. Zero-knowledge proofs are one of the most useful constructions of modern cryptography. Their invention has greatly affected both cryptography and complexity theories. The seemingly paradoxical characteristic of zero-knowledge proofs is that they convince the verifier of the validity of the proposition being proved, yet they yield to further knowledge to him. Two primary applications of zero-knowledge proofs are authentication protocols, as well as sub-protocols which prove that parties involved in some main protocol have acted honestly. In this research, we will survey the models and definitions of zero-knowledge, and analyze their relationship. We then pertain to the interplay between zero-knowledge and authentication models. We will see that a limited authentication model, called smart-card model, is consistent with zero-knowledge from an efficiency point of view. That is, there exist efficient zero-knowledge authentication protocols in this model. After consolidating all definitions of authentication in the smart-card model, we will present a very efficient zero-knowledge authentication protocol in this model. The protocol is zero-knowledge even with respect to infinitely powerful adversaries. Furthermore, it is conjectured that the protocol remains a secure authentication protocol, even in the advent of quantum computers. Next, we consider general authentication models, and observe that current definitions of zero-knowledge are not with these models. After a conceptual analysis of zero-knowledge models, we suggest two hierarchies of zero-knowledge models, and propose a protocol which is zeroknowledge according to one level of these hierarchies, and can be used as an efficient authentication protocol
  9. Keywords:
  10. Authentication ; Interactive Argument ; Cryptography ; Security ; Zero-Knowledge Proof ; Interactive Proof Systems ; Knowledge Proof

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