Cortier, Veronique and Rusinovitch, Michael and Zalinescu, Eugen - Relating two standard notions of secrecy

lmcs:1093 - Logical Methods in Computer Science, July 6, 2007, Volume 3, Issue 3
Relating two standard notions of secrecy

Authors: Cortier, Veronique and Rusinovitch, Michael and Zalinescu, Eugen

Two styles of definitions are usually considered to express that a security protocol preserves the confidentiality of a data s. Reachability-based secrecy means that s should never be disclosed while equivalence-based secrecy states that two executions of a protocol with distinct instances for s should be indistinguishable to an attacker. Although the second formulation ensures a higher level of security and is closer to cryptographic notions of secrecy, decidability results and automatic tools have mainly focused on the first definition so far. This paper initiates a systematic investigation of the situations where syntactic secrecy entails strong secrecy. We show that in the passive case, reachability-based secrecy actually implies equivalence-based secrecy for digital signatures, symmetric and asymmetric encryption provided that the primitives are probabilistic. For active adversaries, we provide sufficient (and rather tight) conditions on the protocol for this implication to hold.

Source :
DOI : 10.2168/LMCS-3(3:2)2007
Volume: Volume 3, Issue 3
Published on: July 6, 2007
Submitted on: January 5, 2007
Keywords: Computer Science - Cryptography and Security,Computer Science - Logic in Computer Science


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