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167
Protocol insecurity with finite number of sessions is NPcomplete
 Theoretical Computer Science
, 2001
"... We investigate the complexity of the protocol insecurity problem for a finite number of sessions (fixed number of interleaved runs). We show that this problem is NPcomplete with respect to a DolevYao model of intruders. The result does not assume a limit on the size of messages and supports nonat ..."
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Cited by 183 (12 self)
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We investigate the complexity of the protocol insecurity problem for a finite number of sessions (fixed number of interleaved runs). We show that this problem is NPcomplete with respect to a DolevYao model of intruders. The result does not assume a limit on the size of messages and supports nonatomic symmetric encryption keys. We also prove that in order to build an attack with a fixed number of sessions the intruder needs only to forge messages of linear size, provided that they are represented as dags.
Formal Methods for Cryptographic Protocol Analysis: Emerging Issues and Trends
, 2003
"... The history of the application of formal methods to cryptographic protocol analysis spans over 20 years and recently has been showing signs of new maturity and consolidation. Not only have a number of specialized tools been developed, and generalpurpose ones been adapted, but people have begun apply ..."
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Cited by 77 (0 self)
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The history of the application of formal methods to cryptographic protocol analysis spans over 20 years and recently has been showing signs of new maturity and consolidation. Not only have a number of specialized tools been developed, and generalpurpose ones been adapted, but people have begun applying these tools to realistic protocols, in many cases supplying feedback to designers that can be used to improve the protocol’s security. In this paper, we will describe some of the ongoing work in this area, as well as describe some of the new challenges and the ways in which they are being met.
A Proof Theory for Generic Judgments
, 2003
"... this paper, we do this by adding the #quantifier: its role will be to declare variables to be new and of local scope. The syntax of the formula # x.B is like that for the universal and existential quantifiers. Following Church's Simple Theory of Types [Church 1940], formulas are given the ..."
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Cited by 76 (20 self)
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this paper, we do this by adding the #quantifier: its role will be to declare variables to be new and of local scope. The syntax of the formula # x.B is like that for the universal and existential quantifiers. Following Church's Simple Theory of Types [Church 1940], formulas are given the type o, and for all types # not containing o, # is a constant of type (# o) o. The expression # #x.B is ACM Transactions on Computational Logic, Vol. V, No. N, October 2003. 4 usually abbreviated as simply # x.B or as if the type information is either simple to infer or not important
Multiset Rewriting and the Complexity of Bounded Security Protocols
 Journal of Computer Security
, 2002
"... We formalize the DolevYao model of security protocols, using a notation based on multiset rewriting with existentials. The goals are to provide a simple formal notation for describing security protocols, to formalize the assumptions of the DolevYao model using this notation, and to analyze the ..."
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Cited by 74 (9 self)
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We formalize the DolevYao model of security protocols, using a notation based on multiset rewriting with existentials. The goals are to provide a simple formal notation for describing security protocols, to formalize the assumptions of the DolevYao model using this notation, and to analyze the complexity of the secrecy problem under various restrictions. We prove that, even for the case where we restrict the size of messages and the depth of message encryption, the secrecy problem is undecidable for the case of an unrestricted number of protocol roles and an unbounded number of new nonces. We also identify several decidable classes, including a dexpcomplete class when the number of nonces is restricted, and an npcomplete class when both the number of nonces and the number of roles is restricted. We point out a remaining open complexity problem, and discuss the implications these results have on the general topic of protocol analysis.
Tree Automata With One Memory, Set Constraints and Cryptographic Protocols
"... We introduce a class of tree automata that perform tests on a memory that is updated using function symbol application and projection. The language emptiness problem for this class of tree automata is shown to be in DEXPTIME. ..."
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Cited by 72 (3 self)
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We introduce a class of tree automata that perform tests on a memory that is updated using function symbol application and projection. The language emptiness problem for this class of tree automata is shown to be in DEXPTIME.
Secrecy Types for Asymmetric Communication
, 2001
"... We develop a typed process calculus for security protocols in which types convey secrecy properties. We focus on asymmetric communication primitives, especially on publickey encryption. These present special difficulties, partly because they rely on related capabilities (e.g., "public" an ..."
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Cited by 68 (6 self)
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We develop a typed process calculus for security protocols in which types convey secrecy properties. We focus on asymmetric communication primitives, especially on publickey encryption. These present special difficulties, partly because they rely on related capabilities (e.g., "public" and "private" keys) with different levels of secrecy and scopes.
A Compositional Logic for Proving Security Properties of Protocols
 Journal of Computer Security
, 2002
"... We present a logic for proving security properties of protocols that use nonces (randomly generated numbers that uniquely identify a protocol session) and publickey cryptography. The logic, designed around a process calculus with actions for each possible protocol step, consists of axioms about ..."
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Cited by 63 (15 self)
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We present a logic for proving security properties of protocols that use nonces (randomly generated numbers that uniquely identify a protocol session) and publickey cryptography. The logic, designed around a process calculus with actions for each possible protocol step, consists of axioms about protocol actions and inference rules that yield assertions about protocols composed of multiple steps. Although assertions are written using only steps of the protocol, the logic is sound in a stronger sense: each provable assertion about an action or sequence of actions holds in any run of the protocol that contains the given actions and arbitrary additional actions by a malicious attacker. This approach lets us prove security properties of protocols under attack while reasoning only about the sequence of actions taken by honest parties to the protocol. The main securityspecific parts of the proof system are rules for reasoning about the set of messages that could reveal secret data and an invariant rule called the "honesty rule." 1
Open Issues in Formal Methods for Cryptographic Protocol Analysis
 In Proceedings of DISCEX 2000
, 2000
"... The history of the application of formal methods to cryptographic protocol analysis spans nearly twenty years, and recently has been showing signs of new maturity and consolidation. A number of specialized tools have been developed, and others have effectively demonstrated that existing generalpurp ..."
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Cited by 63 (5 self)
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The history of the application of formal methods to cryptographic protocol analysis spans nearly twenty years, and recently has been showing signs of new maturity and consolidation. A number of specialized tools have been developed, and others have effectively demonstrated that existing generalpurpose tools can also be applied to these problems with good results. However, with this better understanding of the field comes new problems that strain against the limits of the existing tools. In this paper we will outline some of these new problem areas, and describe what new research needs to be done to to meet the challenges posed.
An improved constraintbased system for the verification of security protocols
 9TH INT. STATIC ANALYSIS SYMP. (SAS), VOLUME LNCS 2477
, 2002
"... We propose a constraintbased system for the verification of security protocols that improves upon the one developed by Millen and Shmatikov [30]. Our system features (1) a significantly more efficient implementation, (2) a monotonic behavior, which also allows to detect flaws associated to partial ..."
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Cited by 61 (15 self)
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We propose a constraintbased system for the verification of security protocols that improves upon the one developed by Millen and Shmatikov [30]. Our system features (1) a significantly more efficient implementation, (2) a monotonic behavior, which also allows to detect flaws associated to partial runs and (3) a more expressive syntax, in which a principal may also perform explicit checks. In this paper we also show why these improvements yield a more effective and practical system.