Towards the Correctness of Security Protocols

AbstractIn [19], the authors presented a type-theoretic approach to the verification of security protocols. In this approach, a universal type system is proposed to capture in a finite way all the possible computations (internal actions or protocol instrumentations) that could be performed by a smart malicious intruder. This reduces the verification of cryptographic protocols to a typing problem where types are attack scenarios. In this paper, we recall this type system and we prove its completeness i.e. if the intruder can learn a message from a given protocol instrumentation, then this message could be infered from the type system. A significant result of this paper is the presentation of a new transformation that allows us to abstract a non-terminating type inference system into a terminating deductive proof system. We demonstrate how these results could be used to establish the security of cryptographic protocols from the secrecy standpoint. Finally, the usefulness and the efficiency of the whole approach is illustrated by proving the correctness of a new version of the Needham-Shoreder protocol with respect to the secrecy property

Alloy experiments for a least privilege separation kernel

A least privilege separation kernel (LPSK) is part of a long-term project known as the Trusted Computing Exemplar (TCX). A major objective of the TCX is the creation of an open framework for high assurance development. A relatively new specification tool called Alloy has shown potential for high assurance development. We implemented the formal security policy model (FSPM) and the formal top level specification (FTLS) of the TCX LPSK in Alloy and concluded that Alloy has few limitations and is more than sufficiently useful, as measured by utility and ease of use, to include in the TCX framework.http://archive.org/details/alloyexperiments109453390Civilian author.Approved for public release; distribution is unlimited

Abstractions pour la vérification de propriétés de sécurité de protocoles cryptographiques

Since the development of computer networks and electronic communications, it becomes important for the public to use secure electronic communications. Cryptographic considerations are part of the answer to the problem and cryptographic protocols describe how to integrate cryptography in actual communications. However, even if the encryption algorithms are robust, there can still remain some attacks due to logical flaw in protocols and formal verification can be used to avoid such flaws. In this thesis, we use abstraction techniques to formally prove various types of properties : secrecy and authentication properties, fairness properties and anonymity.Depuis le développement de l'utilisation des réseaux informatiques et de l'informatisation des communications, il est apparu pour le public un besoin de sécuriser les communications électroniques. Les considérations cryptographiques constituent un élément de réponse au problème de la sécurité des communications et les protocoles cryptographiques décrivent comment intégrer la cryptographie à l'intérieur de communications réelles. Cependant, même dans le cas où les algorithmes de chiffrement sont supposés robustes, les protocoles peuvent présenter des failles de conception exploitables (failles logiques), entrainant un besoin de vérification formelle. Dans cette thèse, nous utilisons des techniques d'abstraction afin de prouver formellement divers types de propriétés. les propriétés de secret et d'authentification, les propriétés de type équité et des propriétés de type anonymat

Computing and estimating information leakage with a quantitative point-to-point information flow model

Information leakage occurs when a system exposes its secret information to an unauthorised entity. Information flow analysis is concerned with tracking flows of information through systems to determine whether they process information securely or leak information. We present a novel information flow model that permits an arbitrary amount of secret and publicly-observable information to occur at any point and in any order in a system. This is an improvement over previous models, which generally assume that systems process a single piece of secret information present before execution and produce a single piece of publicly-observable information upon termination. Our model precisely quantifies the information leakage from secret to publicly-observable values at user-defined points - hence, a "point-to-point" model - using the information-theoretic measures of mutual information and min-entropy leakage; it is ideal for analysing systems of low to moderate complexity. We also present a relaxed version of our information flow model that estimates, rather than computes, the measures of mutual information and min-entropy leakage via sampling of a system. We use statistical techniques to bound the accuracy of the estimates this model provides. We demonstrate how our relaxed model is more suitable for analysing complex systems by implementing it in a quantitative information flow analysis tool for Java programs

Policy based runtime verification of information flow.

Standard security mechanism such as Access control, Firewall and Encryption only focus on controlling the release of information but no limitations are placed on controlling the propagation of that confidential information. The principle problem of controlling sensitive information confidentiality starts after access is granted. The research described in this thesis belongs to the constructive research field where the constructive refers to knowledge contributions being developed as a new framework, theory, model or algorithm. The methodology of the proposed approach is made up of eight work packages. One addresses the research background and the research project requirements. Six are scientific research work packages. The last work package concentrates on the thesis writing up. There is currently no monitoring mechanism for controlling information flow during runtime that support behaviour configurability and User interaction. Configurability is an important requirement because what is considered to be secure today can be insecure tomorrow. The interaction with users is very important in flexible and reliable security monitoring mechanism because different users may have different security requirements. The interaction with monitoring mechanism enables the user to change program behaviours or modify the way that information flows while the program is executing. One of the motivations for this research is the information flow policy in the hand of the end user. The main objective of this research is to develop a usable security mechanism for controlling information flow within a software application during runtime. Usable security refers to enabling users to manage their systems security without defining elaborate security rules before starting the application. Our aim is to provide usable security that enables users to manage their systems' security without defining elaborate security rules before starting the application. Security will be achieved by an interactive process in which our framework will query the user for security requirements for specific pieces of information that are made available to the software and then continue to enforce these requirements on the application using a novel runtime verification technique for tracing information flow. The main achievement of this research is a usable security mechanism for controlling information flow within a software application during runtime. Security will be achieved by an interactive process to enforce user requirements on the application using runtime verification technique for tracing information flow. The contributions are as following. Runtime Monitoring: The proposed runtime monitoring mechanism ensures that the program execution is contains only legal flows that are defined in the information flow policy or approved by the user. Runtime Management: The behaviour of a program that about to leak confidential information will be altered by the monitor according to the user decision. User interaction control: The achieved user interaction with the monitoring mechanism during runtime enable users to change the program behaviours while the program is executing.Libyan Embass