Computationally sound automated proofs of cryptographic schemes
Ngo, Long (2012) Computationally sound automated proofs of cryptographic schemes. PhD thesis, Queensland University of Technology.

Long Ngo Thesis
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Abstract
Proving security of cryptographic schemes, which normally are short algorithms, has been known to be timeconsuming and easy to get wrong. Using computers to analyse their security can help to solve the problem. This thesis focuses on methods of using computers to verify security of such schemes in cryptographic models.
The contributions of this thesis to automated security proofs of cryptographic schemes can be divided into two groups: indirect and direct techniques. Regarding indirect ones, we propose a technique to verify the security of publickeybased key exchange protocols. Security of such protocols has been able to be proved automatically using an existing tool, but in a noncryptographic model. We show that under some conditions, security in that noncryptographic model implies security in a common cryptographic one, the BellareRogaway model [11]. The implication enables one to use that existing tool, which was designed to work with a different type of model, in order to achieve security proofs of publickeybased key exchange protocols in a cryptographic model.
For direct techniques, we have two contributions. The first is a tool to verify DiffieHellmanbased key exchange protocols. In that work, we design a simple programming language for specifying DiffieHellmanbased key exchange algorithms. The language has a semantics based on a cryptographic model, the BellareRogaway model [11]. From the semantics, we build a Hoarestyle logic which allows us to reason about the security of a key exchange algorithm, specified as a pair of initiator and responder programs.
The other contribution to the direct technique line is on automated proofs for computational indistinguishability. Unlike the two other contributions, this one does not treat a fixed class of protocols. We construct a generic formalism which allows one to model the security problem of a variety of classes of cryptographic schemes as the indistinguishability between two pieces of information. We also design and implement an algorithm for solving indistinguishability problems. Compared to the two other works, this one covers significantly more types of schemes, but consequently, it can verify only weaker forms of security.
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ID Code:  54668 

Item Type:  QUT Thesis (PhD) 
Supervisor:  Boyd, Colin 
Keywords:  computational soundness, automated proof, DiffieHellman, key exchange, encryption, random, oracle model, BellareRogaway model, DolevYao, symbolic, bridging, Hoare logic, modular, proof, universal algebra, passive security, INDCPA security. 
Divisions:  Current > QUT Faculties and Divisions > Science & Engineering Faculty 
Institution:  Queensland University of Technology 
Deposited On:  07 Nov 2012 04:59 
Last Modified:  03 Sep 2015 11:28 
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