12,893 research outputs found
Classical Knowledge for Quantum Security
We propose a decision procedure for analysing security of quantum
cryptographic protocols, combining a classical algebraic rewrite system for
knowledge with an operational semantics for quantum distributed computing. As a
test case, we use our procedure to reason about security properties of a
recently developed quantum secret sharing protocol that uses graph states. We
analyze three different scenarios based on the safety assumptions of the
classical and quantum channels and discover the path of an attack in the
presence of an adversary. The epistemic analysis that leads to this and similar
types of attacks is purely based on our classical notion of knowledge.Comment: extended abstract, 13 page
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
Asynchronous Announcements
We propose a multi-agent epistemic logic of asynchronous announcements, where
truthful announcements are publicly sent but individually received by agents,
and in the order in which they were sent. Additional to epistemic modalities
the logic contains dynamic modalities for making announcements and for
receiving them. What an agent believes is a function of her initial uncertainty
and of the announcements she has received. Beliefs need not be truthful,
because announcements already made may not yet have been received. As
announcements are true when sent, certain message sequences can be ruled out,
just like inconsistent cuts in distributed computing.
We provide a complete axiomatization for this \emph{asynchronous announcement
logic} (AA). It is a reduction system that also demonstrates that any formula
in is equivalent to one without dynamic modalities, just as for public
announcement logic. The model checking complexity is in PSPACE. A detailed
example modelling message exchanging processes in distributed computing in
closes our investigation
The Logic of Joint Ability in Two-Player Tacit Games
Logics of joint strategic ability have recently received attention, with arguably the most influential being those in a family that includes Coalition Logic (CL) and Alternating-time Temporal Logic (ATL). Notably, both CL and ATL bypass the epistemic issues that underpin Schelling-type coordination problems, by apparently relying on the meta-level assumption of (perfectly reliable) communication between cooperating rational agents. Yet such epistemic issues arise naturally in settings relevant to ATL and CL: these logics are standardly interpreted on structures where agents move simultaneously, opening the possibility that an agent cannot foresee the concurrent choices of other agents. In this paper we introduce a variant of CL we call Two-Player Strategic Coordination Logic (SCL2). The key novelty of this framework is an operator for capturing coalitional ability when the cooperating agents cannot share strategic information. We identify significant differences in the expressive power and validities of SCL2 and CL2, and present a sound and complete axiomatization for SCL2. We briefly address conceptual challenges when shifting attention to games with more than two players and stronger notions of rationality
Modularity and Openness in Modeling Multi-Agent Systems
We revisit the formalism of modular interpreted systems (MIS) which
encourages modular and open modeling of synchronous multi-agent systems. The
original formulation of MIS did not live entirely up to its promise. In this
paper, we propose how to improve modularity and openness of MIS by changing the
structure of interference functions. These relatively small changes allow for
surprisingly high flexibility when modeling actual multi-agent systems. We
demonstrate this on two well-known examples, namely the trains, tunnel and
controller, and the dining cryptographers.
Perhaps more importantly, we propose how the notions of multi-agency and
openness, crucial for multi-agent systems, can be precisely defined based on
their MIS representations.Comment: In Proceedings GandALF 2013, arXiv:1307.416
Offline and online data: on upgrading functional information to knowledge
This paper addresses the problem of upgrading functional information to knowledge. Functional information is defined as syntactically well-formed, meaningful and collectively opaque data. Its use in the formal epistemology of information theories is crucial to solve the debate on the veridical nature of information, and it represents the companion notion to standard strongly semantic information, defined as well-formed, meaningful and true data. The formal framework, on which the definitions are based, uses a contextual version of the verificationist principle of truth in order to connect functional to semantic information, avoiding Gettierization and decoupling from true informational contents. The upgrade operation from functional information uses the machinery of epistemic modalities in order to add data localization and accessibility as its main properties. We show in this way the conceptual worthiness of this notion for issues in contemporary epistemology debates, such as the explanation of knowledge process acquisition from information retrieval systems, and open data repositories
- …