Preventing Attacks on Machine Readable Travel Documents (MRTDs)

After the terror attacks of 9/11, the U.S. Congress passed legislation that requires in the US Visa Waiver Program to begin issuing issuing machine readable passports that are tamper resistant and incorporate biometric and document authentication identifiers. The International Civil Aviation Organization (ICAO) has issued specifications for Machine Readable Travel Documents (MRTD) that are equipped with a smart card processor to perform biometric identification of the holder. Some countries, such as the United States, will issue machine readable passports that serve only as passports. Other countries, such as the United Kingdom, intend to issue more sophisticated, multi-application passports that can also serve as national identity cards. We have conducted a detailed security analysis of these specificationsm, and we illustrate possible scenarios that could cause a compromise in the security and privacy of holders of such travel documents. Finally, we suggest improved cryptographic protocols and high-assurance smart card operating systems to prevent these compromises and to support electronic visas as well as passports

Intransitive non-interference for cryptographic purposes. In

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Transformations of specifications and proofs to support an evolutionary formal software development

Like other software engineering activities, formal modelling needs to deal with change: bugs and omissions need to be corrected, and changes from the outside need to be dealtwith. In the context of axiomatic specifications and (partly) interactive proofs, the main obstacle is that changes invalidate proofs, which then need to be rebuilt using an inhibitive amount of resources. This thesis proposes to solve the problem by considering the state of a formal development consisting of (potentially buggy) specification and (potentially partial) proofs as one entity and transforming it using preconceived transformations. These transformations are operationally motivated: how would one patch the proofs on paper given a consistent transformation for the specification? They are formulated in terms of the specification and logic language, so as to be usable for several application domains. In order to make the approach compatible with the architecture of existing support systems, development graphs are added as an intermediate concept between specification and proof obligations, and the transformations are extended to work in the presence of the indirection. This leads to a separation of a framework for propagating transformations through development graphs and a reference instantiation that commits to concrete languages and proof representation. The reference instantiation works for many practically relevant scenarios. Other instantiations can be based on the framework

Security via Noninterference: Analyzing Information Flows

Nowadays, the security of information systems is of crucial importance. The large number of detected security vulnerabilities in many systems indicates that new methods for developing secure systems are necessary. These require an appropriate formal foundation. A widely used approach revolves around the notions noninterference and information flow. They allow to express and analyze the absence of illegal information flows and covert channels. In this thesis, the framework of noninterference for state-based asynchronous systems is extended and enriched with new techniques in order to gain a deeper understanding and a broader applicability. As a result, a formal foundation for developing secure systems is obtained. First, new results for the notion of intransitive noninterference are obtained. In particular, a complete characterization by unwinding relations makes the development of a polynomial-time verification algorithm possible in the first place. Second, the previous noninterference definitions are extended with support for policies changing during execution. To capture all resulting security requirements, a new theory of so-called dynamic noninterference is developed and compared to previous approaches. The applicability of this framework is demonstrated by several examples and a complex case study of a distributed dynamic access control system. Third, algorithmic problems are examined, in particular with regard to the question of decidability and complexity of the analyzed security definitions. New undecidability results for some of the present security definitions are obtained, and new efficient algorithms for the verification of both the previously existing and in this thesis developed different notions of noninterference are established

Verification of a Formal Security Model for Multiapplicative Smart Cards

Abstract. We present a generic formal security model for operating systems of multiapplicative smart cards. The model formalizes the main security aspects of secrecy, integrity, secure communication between applications and secure downloading of new applications. The model satisfies a security policy consisting of authentication and intransitive noninterference. The model extends the classical security models of Bell/ LaPadula and Biba, but avoids the need for trusted processes, which are not subject to the security policy by incorporating such processes directly in the model itself. The correctness of the security policy has been formally proven with the VSE II system.