A Fully Abstract Symbolic Semantics for Psi-Calculi

We present a symbolic transition system and bisimulation equivalence for psi-calculi, and show that it is fully abstract with respect to bisimulation congruence in the non-symbolic semantics. A psi-calculus is an extension of the pi-calculus with nominal data types for data structures and for logical assertions representing facts about data. These can be transmitted between processes and their names can be statically scoped using the standard pi-calculus mechanism to allow for scope migrations. Psi-calculi can be more general than other proposed extensions of the pi-calculus such as the applied pi-calculus, the spi-calculus, the fusion calculus, or the concurrent constraint pi-calculus. Symbolic semantics are necessary for an efficient implementation of the calculus in automated tools exploring state spaces, and the full abstraction property means the semantics of a process does not change from the original

Génération automatique de tests pour des propriétés de sécurité

National audienceDans cet article, nous nous intéressons à l'utilisation conjointe de techniques de génération automatique de tests et de synthèse de contrôleurs pour tester des propriétés de sécurité. Nous suivons une approche orientée modèle, c'est-à-dire que nous supposons disposer d'une spécification du comportement du système. Sur celle-ci nous étudions la satisfaction de certaines classes de propriétés de confidentialité et d'intégrité. Nous proposons une méthode qui consiste à calculer automatiquement un modèle du contrôle d'accès idéal assurant ces deux types de propriétés de sécurité. Nous montrons ensuite comment en dériver des cas de tests qui, exécutés sur l'implémentation, permettent de détecter la non-conformité de l'implémentation et sous certaines hypothèses, la violation des propriétés de sécurité, et une éventuelle mauvaise implémentation du contrôle d'accès mis en place

Un esquema de autenticación de usuario basado en el cliente para el entorno de la nube de las cosas

The limited capabilities of IoT devices have resulted in some of the tasks of IoT applications being distributed to a cloud server, which witnessed the arisen of the cloud of things (COT). It enables IoT applications’ development and deployment as a service, providing additional data storage, enhanced processing performance, and fast communication between devices. As COT involves communication between IoT devices, a remote server, and users, remote user authentication is crucial to meeting security demands. Therefore, this study designs a client-based user authentication scheme utilizing smartphone fingerprint recognition technology to fill the gap. The scheme comprises six phases, namely (i) configuration phase, (ii) enrolment phase, (iii) authentication phase, (iv) password update phase, (v) fingerprint revocation phase, and (vi) smartphone revocation phase. The security analysis and automated verification using ProVerif suggested that the scheme is resistant to user impersonating attacks, replay attacks, and man-in-the-middle attacks. The study’s outcome could help secure user credentials from attacks on applications that involve IoT and the cloud.Las capacidades limitadas de los dispositivos IoT han dado como resultado que algunas de las tareas de las aplicaciones IoT se distribuyan a un servidor en la nube, lo que es testigo del surgimiento de la Nube de las Cosas (COT). Esta permite el desarrollo y la implementación de aplicaciones IoT como un servicio, proporcionando almacenamiento de datos adicional, mayor rendimiento de procesamiento y comunicación rápida entre dispositivos. Dado que la COT implica la comunicación entre dispositivos IoT, un servidor remoto y usuarios, la autenticación de usuarios remotos es crucial para satisfacer las demandas de seguridad. Por lo tanto, este estudio diseña un esquema de autenticación de usuario basado en el cliente que utiliza tecnología de reconocimiento de huellas digitales en teléfonos inteligentes para colmar la brecha. El esquema consta de seis fases: (i) fase de configuración, (ii) fase de inscripción, (iii) fase de autenticación, (iv) fase de actualización de contraseña, (v) fase de revocación de huellas digitales y (vi) fase de revocación de teléfonos inteligentes. A partir del análisis de seguridad y la verificación automatizada con ProVerif surge que el esquema es resistente a diferentes ataques, por ejemplo ataques de suplantación de identidad del usuario, los ataques de repetición y los ataques manin- the-middle. El resultado del estudio podría ayudar a proteger las credenciales de los usuarios de los ataques a las aplicaciones que involucran IoT y la nube.Facultad de Informátic

Exploiting Symmetries When Proving Equivalence Properties for Security Protocols

International audienceVerification of privacy-type properties for cryptographic protocols in an active adversarial environment, modelled as a behavioural equivalence in concurrent-process calculi, exhibits a high computational complexity. While undecidable in general, for some classes of common cryptographic primitives the problem is coNEXP-complete when the number of honest participants is bounded.In this paper we develop optimisation techniques for verifying equivalences, exploiting symmetries between the two processes under study. We demonstrate that they provide a significant (several orders of magnitude) speed-up in practice, thus increasing the size of the protocols that can be analysed fully automatically

Verification of Stateful Cryptographic Protocols with Exclusive OR

International audienceIn cryptographic protocols, in particular RFID protocols, exclusive-or (XOR) operations are common. Due to the inherent complexity of faithful models of XOR, there is only limited tool support for the verification of cryptographic protocols using XOR. In this paper, we improve the TAMARIN prover and its underlying theory to deal with an equational theory modeling XOR operations. The XOR theory can be combined with all equational theories previously supported, including user-defined equational theories. This makes TAMARIN the first verification tool for cryptographic protocols in the symbolic model to support simultaneously this large set of equational theories, protocols with global mutable state, an unbounded number of sessions, and complex security properties including observational equivalence. We demonstrate the effectiveness of our approach by analyzing several protocols that rely on XOR, in particular multiple RFID-protocols, where we can identify attacks as well as provide proofs

Effective symbolic protocol analysis via equational irreducibility conditions

We address a problem that arises in cryptographic protocol analysis when the equational properties of the cryptosystem are taken into account: in many situations it is necessary to guarantee that certain terms generated during a state exploration are in normal form with respect to the equational theory. We give a tool-independent methodology for state exploration, based on unification and narrowing, that generates states that obey these irreducibility constraints, called contextual symbolic reachability analysis, prove its soundness and completeness, and describe its implementation in the Maude-NPA protocol analysis tool. Contextual symbolic reachability analysis also introduces a new type of unification mechanism, which we call asymmetric unification, in which any solution must leave the right side of the solution irreducible. We also present experiments showing the effectiveness of our methodology.S. Escobar and S. Santiago have been partially supported by the EU (FEDER) and the Spanish MEC/MICINN under grant TIN 2010-21062-C02-02, and by Generalitat Valenciana PROMETEO2011/052. The following authors have been partially supported by NSF: S. Escobar, J. Meseguer and R. Sasse under grants CCF 09- 05584, CNS 09-04749, and CNS 09-05584; D. Kapur under grant CNS 09-05222; C. Lynch, Z. Liu, and C. Meadows under grant CNS 09-05378, and P. Narendran and S. Erbatur under grant CNS 09-05286.Erbatur, S.; Escobar Román, S.; Kapur, D.; Liu, Z.; Lynch, C.; Meadows, C.; Meseguer, J.... (2012). Effective symbolic protocol analysis via equational irreducibility conditions. En Computer Security - ESORICS 2012. Springer Verlag (Germany). 7459:73-90. doi:10.1007/978-3-642-33167-1_5S73907459IEEE 802.11 Local and Metropolitan Area Networks: Wireless LAN Medium Access Control (MAC) and Physical (PHY) Specifications (1999)Abadi, M., Cortier, V.: Deciding knowledge in security protocols under equational theories. Theor. 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IOS Press (2011)Blanchet, B., Abadi, M., Fournet, C.: Automated verification of selected equivalences for security protocols. J. Log. Algebr. Program. 75(1), 3–51 (2008)Ciobâcă, Ş., Delaune, S., Kremer, S.: Computing Knowledge in Security Protocols under Convergent Equational Theories. In: Schmidt, R.A. (ed.) CADE-22. LNCS (LNAI), vol. 5663, pp. 355–370. Springer, Heidelberg (2009)Comon-Lundh, H., Delaune, S.: The Finite Variant Property: How to Get Rid of Some Algebraic Properties. In: Giesl, J. (ed.) RTA 2005. LNCS, vol. 3467, pp. 294–307. Springer, Heidelberg (2005)Comon-Lundh, H., Delaune, S., Millen, J.: Constraint solving techniques and enriching the model with equational theories. In: Cortier, V., Kremer, S. (eds.) Formal Models and Techniques for Analyzing Security Protocols. Cryptology and Information Security Series, vol. 5, pp. 35–61. IOS Press (2011)Comon-Lundh, H., Shmatikov, V.: Intruder deductions, constraint solving and insecurity decision in presence of exclusive or. In: LICS, pp. 271–280. IEEE Computer Society (2003)Ciobâcă, Ş.: Knowledge in security protocolsDolev, D., Yao, A.C.-C.: On the security of public key protocols (extended abstract). In: FOCS, pp. 350–357 (1981)Escobar, S., Meadows, C., Meseguer, J.: A rewriting-based inference system for the NRL protocol analyzer and its meta-logical properties. Theoretical Computer Science 367(1-2), 162–202 (2006)Escobar, S., Meadows, C., Meseguer, J.: State Space Reduction in the Maude-NRL Protocol Analyzer. In: Jajodia, S., Lopez, J. (eds.) ESORICS 2008. LNCS, vol. 5283, pp. 548–562. Springer, Heidelberg (2008)Escobar, S., Meadows, C., Meseguer, J.: Maude-NPA: Cryptographic Protocol Analysis Modulo Equational Properties. In: Aldini, A., Barthe, G., Gorrieri, R. (eds.) FOSAD 2007. LNCS, vol. 5705, pp. 1–50. Springer, Heidelberg (2009)Escobar, S., Meadows, C., Meseguer, J., Santiago, S.: State space reduction in the maude-nrl protocol analyzer. Information and Computation (in press, 2012)Escobar, S., Sasse, R., Meseguer, J.: Folding variant narrowing and optimal variant termination. J. Log. Algebr. Program (in press, 2012)Thayer Fabrega, F.J., Herzog, J., Guttman, J.: Strand Spaces: What Makes a Security Protocol Correct? Journal of Computer Security 7, 191–230 (1999)Jouannaud, J.-P., Kirchner, H.: Completion of a set of rules modulo a set of equations. SIAM J. Comput. 15(4), 1155–1194 (1986)Küsters, R., Truderung, T.: Using ProVerif to analyze protocols with Diffie-Hellman exponentiation. In: CSF, pp. 157–171. IEEE Computer Society (2009)Küsters, R., Truderung, T.: Reducing protocol analysis with xor to the xor-free case in the horn theory based approach. Journal of Automated Reasoning 46(3-4), 325–352 (2011)Liu, Z., Lynch, C.: Efficient General Unification for XOR with Homomorphism. In: Bjørner, N., Sofronie-Stokkermans, V. (eds.) CADE 2011. LNCS, vol. 6803, pp. 407–421. 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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