Practical client puzzles in the standard model

Kuppusamy, Lakshmi, Rangasamy, Jothi, Stebila, Douglas, Boyd, Colin, & Nieto, Juan Gonzalez (2012) Practical client puzzles in the standard model. In Youm, Heung Youl & Won, Yujae (Eds.) Proceedings of the 7th ACM Symposium on Information, Computer and Communications Security, SoonChunHyang University, Korea, Korea.

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Client puzzles are cryptographic problems that are neither easy nor hard to solve. Most puzzles are based on either number theoretic or hash inversions problems. Hash-based puzzles are very efficient but so far have been shown secure only in the random oracle model; number theoretic puzzles, while secure in the standard model, tend to be inefficient. In this paper, we solve the problem of constucting cryptographic puzzles that are secure int he standard model and are very efficient. We present an efficient number theoretic puzzle that satisfies the puzzle security definition of Chen et al. (ASIACRYPT 2009). To prove the security of our puzzle, we introduce a new variant of the interval discrete logarithm assumption which may be of independent interest, and show this new problem to be hard under reasonable assumptions. Our experimental results show that, for 512-bit modulus, the solution verification time of our proposed puzzle can be up to 50x and 89x faster than the Karame-Capkum puzzle and the Rivest et al.'s time-lock puzzle respectively. In particular, the solution verification tiem of our puzzle is only 1.4x slower than that of Chen et al.'s efficient hash based puzzle.

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ID Code: 51506
Item Type: Conference Paper
Refereed: Yes
Keywords: Client puzzle, Denial of service, Interval discrete log problem, Factorisation, Puzzle unforgeability, Puzzle difficulty
Subjects: Australian and New Zealand Standard Research Classification > INFORMATION AND COMPUTING SCIENCES (080000) > COMPUTER SOFTWARE (080300) > Computer System Security (080303)
Divisions: Current > Schools > School of Electrical Engineering & Computer Science
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2012 ACM
Deposited On: 10 Jul 2012 01:29
Last Modified: 12 Jun 2013 14:55

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