1,064 research outputs found
Actor Network Procedures as Psi-calculi for Security Ceremonies
The actor network procedures of Pavlovic and Meadows are a recent graphical
formalism developed for describing security ceremonies and for reasoning about
their security properties. The present work studies the relations of the actor
network procedures (ANP) to the recent psi-calculi framework. Psi-calculi is a
parametric formalism where calculi like spi- or applied-pi are found as
instances. Psi-calculi are operational and largely non-graphical, but have
strong foundation based on the theory of nominal sets and process algebras. One
purpose of the present work is to give a semantics to ANP through psi-calculi.
Another aim was to give a graphical language for a psi-calculus instance for
security ceremonies. At the same time, this work provides more insight into the
details of the ANPs formalization and the graphical representation.Comment: In Proceedings GraMSec 2014, arXiv:1404.163
Seeing the full picture: the case for extending security ceremony analysis
The concept of the security ceremony was introduced a few years ago to complement the concept of the security protocol with everything about the context in which a protocol is run. In particular, such context involves the human executors of a protocol. When including human actors, human protocols become the focus, hence the concept of the security ceremony can be seen as part of the domain of socio-technical studies. This paper addresses the problem of ceremony analysis lacking the full view of human protocols. This paper categorises existing security ceremony analysis work and illustrates how the ceremony picture could be extended to support a more comprehensive analysis. The paper explores recent weaknesses found on the Amazon\u27s web interface to illustrate different approaches to the analysis of the full ceremony picture
Actor-network procedures: Modeling multi-factor authentication, device pairing, social interactions
As computation spreads from computers to networks of computers, and migrates
into cyberspace, it ceases to be globally programmable, but it remains
programmable indirectly: network computations cannot be controlled, but they
can be steered by local constraints on network nodes. The tasks of
"programming" global behaviors through local constraints belong to the area of
security. The "program particles" that assure that a system of local
interactions leads towards some desired global goals are called security
protocols. As computation spreads beyond cyberspace, into physical and social
spaces, new security tasks and problems arise. As networks are extended by
physical sensors and controllers, including the humans, and interlaced with
social networks, the engineering concepts and techniques of computer security
blend with the social processes of security. These new connectors for
computational and social software require a new "discipline of programming" of
global behaviors through local constraints. Since the new discipline seems to
be emerging from a combination of established models of security protocols with
older methods of procedural programming, we use the name procedures for these
new connectors, that generalize protocols. In the present paper we propose
actor-networks as a formal model of computation in heterogenous networks of
computers, humans and their devices; and we introduce Procedure Derivation
Logic (PDL) as a framework for reasoning about security in actor-networks. On
the way, we survey the guiding ideas of Protocol Derivation Logic (also PDL)
that evolved through our work in security in last 10 years. Both formalisms are
geared towards graphic reasoning and tool support. We illustrate their workings
by analysing a popular form of two-factor authentication, and a multi-channel
device pairing procedure, devised for this occasion.Comment: 32 pages, 12 figures, 3 tables; journal submission; extended
references, added discussio
Gulfs of Expectation: Eliciting and Verifying Differences in Trust Expectations using Personas
Personas are a common tool used in Human Computer Interaction to represent the needs and expectations of a systemâs stakeholders, but they are also grounded in large amounts of qualitative data. Our aim is to make use of this data to anticipate the differences between a user personaâs expectations of a system, and the expectations held by its developers. This paper introduces the idea of gulfs of expectation â the gap between the expectations held by a user about a system and its developers, and the expectations held by a developer about the system and its users. By evaluating these differences in expectation against a formal representation of a system, we demonstrate how differences between the anticipated user and developer mental models of the system can be verified. We illustrate this using a case study where persona characteristics were analysed to identify divergent behaviour and potential security breaches as a result of differing trust expectations
Ceremonies for End-to-End Verifiable Elections
State-of-the-art e-voting systems rely on voters to perform certain actions to ensure that the election authorities are not manipulating the election result. This so-called âend-to-end (E2E) verifiabilityâ is the hallmark of current e-voting protocols; nevertheless, thorough analysis of current systems is still far from being complete. In this work, we initiate the study of e-voting protocols as ceremonies. A ceremony, as introduced by Ellison [23], is an extension of the notion of a protocol that includes human participants as separate nodes of the system that should be taken into account when performing the security analysis. that centers on the two properties of end-to-end verifiability and voter privacy and allows the consideration of arbitrary behavioural distributions for the human participants. We then analyse the Helios system as an e-voting ceremony. Security in the e-voting ceremony model requires the specification of a class of human behaviours with respect to which the security properties can be preserved. We show how end-to-end verifiability and voter privacy are sensitive to human behaviour in the protocol by characterizing the set of behaviours under which the security can be preserved and also showing explicit scenarios where it fails. We then provide experimental evaluation with human subjects from two different sources where people used Helios: the elections of the International Association for Cryptologic Research (IACR) and a poll of senior year computer science students. We report on the auditing behaviour of the participants as we measured it and we discuss the effects on the level of certainty that can be given by each of the two electorates. The outcome of our analysis is a negative one: the auditing behaviour of people (including cryptographers) is not sufficient to ensure the correctness of the tally with good probability in either case studied. The same holds true even for simulated data that capture the case of relatively well trained participants while, finally, the security of the ceremony can be shown but under the assumption of essentially ideally behaving human subjects. We note that while our results are stated for Helios, they automatically transfer to various other e-voting systems that, as Helios, rely on client-side encryption to encode the voterâs choice
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