We present an architecture and tools for verifying implementations of security protocols. Our implementations can run with both concrete and symbolic implementations of cryptographic algorithms. The concrete implementation is for production and interoperability testing. The symbolic implementation is for debugging and formal verification. We develop our approach for protocols written in F#, a dialect of ML, and verify them by compilation to ProVerif, a resolution-based theorem prover for cryptographic protocols. We establish the correctness of this compilation scheme, and we illustrate our approach with protocols for Web Services security.

This article presents a model and implementation techniques for speeding up constraint propagation. Three fundamental approaches to improving constraint propagation based on propagators as implementations of constraints are explored: keeping track of which propagators are at fixpoint, choosing which propagator to apply next, and how to combine several propagators for the same constraint. We show how idempotence reasoning and events help track fixpoints more accurately. We improve these methods by using them dynamically (taking into account current variable domains to improve accuracy). We define priority-based approaches to choosing a next propagator and show that dynamic priorities can improve propagation. We illustrate that the use of multiple propagators for the same constraint can be advantageous with priorities, and introduce staged propagators that combine the effects of multiple propagators with priorities for greater efficiency.

WS-SecurityPolicy is a declarative language for configuring web services security mechanisms. We describe a formal semantics for WS-SecurityPolicy and propose a more abstract language for specifying secure links between web services and their clients. We present the architecture and implementation of tools that (1) compile policy files from link specifications, and (2) verify by invoking a theorem prover whether a set of policy files run by any number of senders and receivers correctly implements the goals of a link specification, in spite of active attackers. Policy-driven web services implementations are prone to the usual subtle vulnerabilities associated with cryptographic protocols; our tools help prevent such vulnerabilities. We can verify policies when first compiled from link specifications, and also re-verify policies against their original goals after any modifications during deployment. Moreover, we present general security theorems for all configurations that rely on compiled policies.

Atomicity is a fundamental correctness property in multithreaded programs. A method is atomic if, for every execution, there is an equivalent serial execution in which the actions of the method are not interleaved with actions of other threads. Atomic methods are amenable to sequential reasoning, which significantly facilitates subsequent analysis and verification. This article presents a type system for specifying and verifying the atomicity of methods in multithreaded Java programs using a synthesis of Lipton's theory of reduction and type systems for race detection. The type system supports guarded, write-guarded, and unguarded fields, as well as thread-local data, parameterized classes and methods, and protected locks. We also present an algorithm for verifying atomicity via type inference. We have applied our type checker and type inference tools to a number of commonly used Java library classes and programs. These tools were able to verify the vast majority of methods in these benchmarks as atomic, indicating that atomicity is a widespread methodology for multithreaded programming. In addition, reported atomicity violations revealed some subtle errors in the synchronization disciplines of these programs.

We propose a type system for lock-freedom in the π-calculus, which guarantees that certain communications will eventually succeed. Distinguishing features of our type system are: it can verify lock-freedom of concurrent programs that have sophisticated recursive communication structures; it can be fully automated; it is hybrid, in that it combines a type system for lock-freedom with local reasoning about deadlock-freedom, termination, and confluence analyses. Moreover, the type system is parameterized by deadlock-freedom/termination/confluence analyses, so that any methods (e.g. type systems and model checking) can be used for those analyses. A lock-freedom analysis tool has been implemented based on the proposed type system, and tested for nontrivial programs.

We provide a parametric framework for verifying safety properties of concurrent heap-manipulating programs. The framework combines thread-scheduling information with information about the shape of the heap. This leads to verification algorithms that are more precise than existing techniques. The framework also provides a precise shape-analysis algorithm for concurrent programs. In contrast to most existing verification techniques, we do not put a bound on the number of allocated objects. The framework produces interesting results even when analyzing programs with an unbounded number of threads. The framework is applied to successfully verify the following properties of a concurrent program: —Concurrent manipulation of linked-list based ADT preserves the ADT datatype invariant. —The program does not perform inconsistent updates due to interference. —The program does not reach a deadlock. —The program does not produce runtime errors due to illegal thread interactions. We also found bugs in erroneous programs violating such properties. A prototype of our framework has been implemented and applied to small, but interesting, example programs.

This article defines AspectML, a typed functional, aspect-oriented programming language. The main contribution of AspectML is the seamless integration of polymorphism, run-time type analysis and aspect-oriented programming language features. In particular, AspectML allows programmers to define type-safe polymorphic advice using pointcuts constructed from a collection of polymorphic join points. AspectML also comes equipped with a type inference algorithm that conservatively extends Hindley--Milner type inference. To support first-class polymorphic point-cut designators, a crucial feature for developing aspect-oriented profiling or logging libraries, the algorithm blends the conventional Hindley--Milner type inference algorithm with a simple form of local type inference. We give our language operational meaning via a type-directed translation into an expressive type-safe intermediate language. Many complexities of the source language are eliminated in this translation, leading to a modular specification of its semantics. One of the novelties of the intermediate language is the definition of polymorphic labels for marking control-flow points. When a set of labels is assembled as a pointcut, the type of each label is an instance of the type of the pointcut.

In the context of statically typed, class-based languages , we investigate classes that can be extended with trait composition. A trait is a collection of methods without state; it can be viewed as an incomplete stateless class . Traits can be composed in any order, but only make sense when imported by a class that provides state variables and additional methods to disambiguate conflicting names arising between the imported traits. We introduce FeatherTrait Java (FTJ), a conservative extension of the simple lightweight class-based calculus Featherweight Java (FJ) with statically typed traits . In FTJ, classes can be built using traits as basic behavioral bricks; method conflicts between imported traits must be resolved explicitly by the user either by (i) aliasing or excluding method names in traits, or by (ii) overriding explicitly the conflicting methods in the class or in the trait itself. We present an operational semantics with a lookup algorithm, and a sound type system that guarantees that evaluating a well-typed expression never yields a message-not-understood run-time error nor gets the interpreter stuck. We give examples of the increased expressive power of the trait-based inheritance model. The resulting calculus appears to be a good starting point for a rigorous mathematical analysis of typed class-based languages featuring trait-based inheritance.

Despite significant progress in the theory and practice of program analysis, analyzing properties of heap data has not reached the same level of maturity as the analysis of static and stack data. The spatial and temporal structure of stack and static ...

The π-calculus, a calculus of mobile processes, can compositionally represent dynamics of major programming constructs by decomposing them into name passing. The present work reports our experience in using a linear/affine typed π-calculus for the analysis and development of type-based analyses for programming languages, focussing on secure information flow analysis. After presenting a basic typed calculus for secrecy, we demonstrate its usage by a sound embedding of the dependency core calculus (DCC) and the development of the call-by-value version of DCC. The secrecy analysis is then extended to stateful computation, for which we develop a novel type discipline for imperative programming language that extends a secure multi-threaded imperative language by Smith and Volpano with general references and higher-order procedures. In each analysis, the embedding gives a simple proof of noninterference.