IACR News item: 18 July 2014
Nico Döttling, Daniel Kraschewski, Jörn Müller-Quade, Tobias Nilges
ePrint ReportWe investigate the natural question of what is possible if an adversary can reset a token at most a bounded number of times (e.g., because each resetting attempt imposes a significant risk to trigger a self-destruction mechanism of the token). Somewhat surprisingly, our results come close to the known positive results with respect to non-resettable stateful tokens. In particular, we construct polynomially many instances of statistically secure and universally composable oblivious transfer, using only a constant number of tokens. Our techniques have some abstract similarities to previous solutions, which we grasp by defining a new security property for protocols that use oracle access. Additionally, we apply our techniques to zero-knowledge proofs and obtain a protocol that achieves the same properties as bounded-query zero-knowledge PCPs (Kilian, Petrank, Tardos; STOC 1997), even if a malicious prover may issue stateful PCP oracles.
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