1,312 research outputs found
A Spatial-Epistemic Logic for Reasoning about Security Protocols
Reasoning about security properties involves reasoning about where the
information of a system is located, and how it evolves over time. While most
security analysis techniques need to cope with some notions of information
locality and knowledge propagation, usually they do not provide a general
language for expressing arbitrary properties involving local knowledge and
knowledge transfer. Building on this observation, we introduce a framework for
security protocol analysis based on dynamic spatial logic specifications. Our
computational model is a variant of existing pi-calculi, while specifications
are expressed in a dynamic spatial logic extended with an epistemic operator.
We present the syntax and semantics of the model and logic, and discuss the
expressiveness of the approach, showing it complete for passive attackers. We
also prove that generic Dolev-Yao attackers may be mechanically determined for
any deterministic finite protocol, and discuss how this result may be used to
reason about security properties of open systems. We also present a
model-checking algorithm for our logic, which has been implemented as an
extension to the SLMC system.Comment: In Proceedings SecCo 2010, arXiv:1102.516
YAPA: A generic tool for computing intruder knowledge
Reasoning about the knowledge of an attacker is a necessary step in many
formal analyses of security protocols. In the framework of the applied pi
calculus, as in similar languages based on equational logics, knowledge is
typically expressed by two relations: deducibility and static equivalence.
Several decision procedures have been proposed for these relations under a
variety of equational theories. However, each theory has its particular
algorithm, and none has been implemented so far. We provide a generic procedure
for deducibility and static equivalence that takes as input any convergent
rewrite system. We show that our algorithm covers most of the existing decision
procedures for convergent theories. We also provide an efficient
implementation, and compare it briefly with the tools ProVerif and KiSs
Relating two standard notions of secrecy
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.Comment: 29 pages, published in LMC
Probabilistic Opacity for Markov Decision Processes
Opacity is a generic security property, that has been defined on (non
probabilistic) transition systems and later on Markov chains with labels. For a
secret predicate, given as a subset of runs, and a function describing the view
of an external observer, the value of interest for opacity is a measure of the
set of runs disclosing the secret. We extend this definition to the richer
framework of Markov decision processes, where non deterministic choice is
combined with probabilistic transitions, and we study related decidability
problems with partial or complete observation hypotheses for the schedulers. We
prove that all questions are decidable with complete observation and
-regular secrets. With partial observation, we prove that all
quantitative questions are undecidable but the question whether a system is
almost surely non opaque becomes decidable for a restricted class of
-regular secrets, as well as for all -regular secrets under
finite-memory schedulers
Efficient First-Order Temporal Logic for Infinite-State Systems
In this paper we consider the specification and verification of
infinite-state systems using temporal logic. In particular, we describe
parameterised systems using a new variety of first-order temporal logic that is
both powerful enough for this form of specification and tractable enough for
practical deductive verification. Importantly, the power of the temporal
language allows us to describe (and verify) asynchronous systems, communication
delays and more complex properties such as liveness and fairness properties.
These aspects appear difficult for many other approaches to infinite-state
verification.Comment: 16 pages, 2 figure
Decidability of trace equivalence for protocols with nonces
International audiencePrivacy properties such as anonymity, unlinkability, or vote secrecy are typically expressed as equivalence properties.In this paper, we provide the first decidability result for trace equivalence of security protocols, for an unbounded number of sessions and unlimited fresh nonces. Our class encompasses most symmetric key protocols of the literature, in their tagged variant
Privacy Architectures: Reasoning About Data Minimisation and Integrity
Privacy by design will become a legal obligation in the European Community if
the Data Protection Regulation eventually gets adopted. However, taking into
account privacy requirements in the design of a system is a challenging task.
We propose an approach based on the specification of privacy architectures and
focus on a key aspect of privacy, data minimisation, and its tension with
integrity requirements. We illustrate our formal framework through a smart
metering case study.Comment: appears in STM - 10th International Workshop on Security and Trust
Management 8743 (2014
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