The Transmission Control Protocol.

The B Book

We present unikernels, a new approach to deploying cloud services via applications written in high-level source code. Unikernels are single-purpose appliances that are compile-time specialised into standalone kernels, and sealed against modification when deployed to a cloud platform. In return they offer significant reduction in image sizes, improved efficiency and security, and should reduce operational costs. Our Mirage prototype compiles OCaml code into unikernels that run on commodity clouds and offer an order of magnitude reduction in code size without significant performance penalty. The architecture combines static type-safety with a single address-space layout that can be made immutable via a hypervisor extension. Mirage contributes a suite of type-safe protocol libraries, and our results demonstrate that the hypervisor is a platform that overcomes the hardware compatibility issues that have made past library operating systems impractical to deploy in the real-world.

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Unikernels: library operating systems for the cloud

Functional Programming Languages and Computer Architecture

Security protocols are one of the most critical elements in enabling the secure communication and processing of information, ensuring its confidentiality, integrity, authenticity and availability. These protocols are vulnerable to a host of subtle attacks, so designing protocols to be impervious to such attacks has proved to be extremely challenging and error prone.This book provides a thorough and detailed understanding of one of the most effective approaches to the design and evaluation of security critical systems, describing the role of security protocols in distributed secure systems and the vulnerabilities to which they are prey.The authors introduce security protocols, the role they play and the cryptographic mechanisms they employ, and detail their role in security architectures, e-commerce, e-cash etc. Precise characterizations of key concepts in information security, such as confidentiality, authentication and integrity are introduced and a range of tools and techniques are described which will ensure that a protocol guarantees certain security services under appropriate assumptions.Modeling and Analysis of Security Protocols provides: An in-depth discussion of the nature and role of security protocols and their vulnerabilities. A rigorous framework in which security protocols and properties can be defined in detail. An understanding of the tools and techniques used to design and evaluate security protocols.

/pdf/the-modelling-and-analysis-of-security-protocols-the-csp-peb985ee9l.pdf

The modelling and analysis of security protocols: the csp approach

Constraint LTL, a generalization of LTL over Presburger constraints, is often used as a formal language to specify the behavior of operational models with constraints. The freeze quantifier can be part of the language, as in some real-time logics, but this variable-binding mechanism is quite general and ubiquitous in many logical languages (first-order temporal logics, hybrid logics, logics for sequence diagrams, navigation logics, etc.). We show that Constraint LTL over the simple domain augmented with the freeze operator is undecidable which is a surprising result regarding the poor language for constraints (only equality tests). Many versions of freeze-free constraint LTL are decidable over domains with qualitative predicates and our undecidability result actually establishes /spl Sigma//sub 1//sup 1/ -completeness. On the positive side, we provide complexity results when the domain is finite (EXPSPACE-completeness) or when the formulae are flat in a sense introduced in the paper.

/pdf/on-the-freeze-quantifier-in-constraint-ltl-decidability-and-3odusv07o5.pdf

On the freeze quantifier in constraint LTL: decidability and complexity

A concurrent system is data-independent with respect to a data type when the only operation it can perform on values of that type is equality testing. The system can also assign, input, nondeterministically choose, and output such values. Based on this intuitive definition, syntactic restrictions which ensure data-independence have been formulated for a variety of different formalisms. However, it is difficult to see how these are related.

We present the first semantic definition of data-independence which allows equality testing, and its extension which allows constant symbols and predicate symbols. Both are special cases of a definition of when a family of labelled transition systems is parametric. This provides a unified approach to data-independence and its extensions.

The paper also contains two theorems which, given a system and a specification which are data-independent, enable the verification for all instantiations of the data types (and of the constant symbols and the predicate symbols, in the case of the extension) to be reduced to the verification for a finite number of finite instantiations.

We illustrate the applicability of the approach to particular formalisms by a programming language similar to UNITY.

A unifying approach to data-independence

To be accepted, a cryptographic scheme must come with a proof that it satisfies some standard security properties. However, because cryptographic schemes are based on non-trivial mathematics, proofs are error-prone and difficult to check. The main contributions of this paper are a refinement of the game-based approach to security proofs, and its implementation on top of the proof assistant Coq. The proof assistant checks that the proof is correct and deals with the mundane part of the proof. An interesting feature of our framework is that our proofs are formal enough to be mechanically checked, but still readable enough to be humanly checked. We illustrate the use of our framework by proving in a systematic way the so-called semantic security of the encryption scheme Elgamal and its hashed version.

/pdf/a-framework-for-game-based-security-proofs-4xcdg97zsk.pdf

A framework for game-based security proofs

Logical relations and their generalisations are a fundamental tool in proving properties of lambda calculi, for example, for yielding sound principles for observational equivalence. We propose a natural notion of logical relations that is able to deal with the monadic types of Moggi's computational lambda calculus. The treatment is categorical, and is based on notions of subsconing, mono factorisation systems and monad morphisms. Our approach has a number of interesting applications, including cases for lambda calculi with non-determinism (where being in a logical relation means being bisimilar), dynamic name creation and probabilistic systems.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0960129508007172

Logical relations for monadic types

Logical relations andt heir generalizations are a fundamental tool in proving properties of lambda-calculi, e.g., yielding sound principles for observational equivalence. We propose a natural notion of logical relations able to deal with the monadic types of Moggi's computational lambda-calculus. The treatment is categorical, and is based on notions of subsconing and distributivity laws for monads. Our approach has a number of interesting applications, including cases for lambda-calculi with non-determinism (where being in logical relation means being bisimilar), dynamic name creation, and probabilistic systems.

David Nowak

Papers

On the freeze quantifier in constraint LTL: decidability and complexity

A unifying approach to data-independence

A framework for game-based security proofs

Logical relations for monadic types

Logical Relations for Monadic Types