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Intruders with Caps

Siva Anantharaman 1 Paliath Narendran 2 Michaël Rusinowitch 3
3 CASSIS - Combination of approaches to the security of infinite states systems
FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174), INRIA Lorraine, LORIA - Laboratoire Lorrain de Recherche en Informatique et ses Applications
Abstract : In the analysis of cryptographic protocols, a "treacherous" set of terms is one from which an intruder can get access to what was intended to be secret, by adding on to the top of a sequence of elements of this set, a "cap" ormed of symbols legally part of his/her knowledge. In this paper, we give sufficient conditions on the rewrite system modeling the intruder's abilities, such as using encryption and decryption functions, to ensure that it is decidable if such caps exist. The following classes of intruder systems are studied: linear, dwindling, Delta-strong, and optimally reducing; and depending on the class considered, the cap problem (``find a cap for a given set of terms'') is shown respectively to be in P, NP-complete, decidable, and undecidable.
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Contributor : Siva Anantharaman <>
Submitted on : Wednesday, May 2, 2007 - 11:00:02 AM
Last modification on : Wednesday, September 16, 2020 - 10:43:02 AM
Long-term archiving on: : Tuesday, April 6, 2010 - 11:32:18 PM


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  • HAL Id : hal-00144178, version 1


Siva Anantharaman, Paliath Narendran, Michaël Rusinowitch. Intruders with Caps. 2007. ⟨hal-00144178⟩



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