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We intend to narrow the gap between concrete implementations of cryptographic protocols and their verified models. We develop and verify a small functional implementation of the Transport Layer Security protocol (TLS 1.0). We make use of the same executable code for interoperability testing against mainstream implementations, for automated symbolic… (More)

We present and analyze monitoring algorithms for a safety fragment of metric temporal logics, which differ in their underlying time model. The time models considered have either dense or discrete time domains and are point-based or interval-based. Our analysis reveals differences and similarities between the time models for monitoring and highlights key… (More)

We consider the problem of finding short strings that contain all permutations of order k over an alphabet of size n, with k ≤ n. We show constructively that k(n − 2) + 3 is an upper bound on the length of shortest such strings, for n ≥ k ≥ 10. Consequently, for n ≥ 10, the shortest strings that contain all permutations of order n have length at most n 2 −… (More)

There is a large amount of work dedicated to the formal verification of security protocols. In this article, we revisit and extend the NP-complete decision procedure for a bounded number of sessions. We use a, now standard, deducibility constraint formalism for modeling security protocols. Our first contribution is to give a simple set of constraint… (More)

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… (More)

We propose a general transformation that maps a protocol secure in an extremely weak sense (essentially in a model where no adversary is present) into a protocol that is secure against a fully active adversary which interacts with an unbounded number of protocol sessions, and has absolute control over the network. The transformation works for arbitrary… (More)

In system monitoring, one is often interested in checking properties of aggregated data. Current policy monitoring approaches are limited in the kinds of aggregations they handle. To rectify this, we extend an expressive language, metric first-order temporal logic, with aggregation operators. Our extension is inspired by the aggregation operators common in… (More)

—IT systems manage increasing amounts of sensitive data and there is a growing concern that they comply with policies that regulate data usage. In this article, we use temporal logic to express policies, and runtime monitoring to check system compliance. While well-established methods for monitoring linearly-ordered system behavior exist, a major challenge… (More)

—We have previously presented a monitoring algorithm for compliance checking of policies formalized in an expressive metric first-order temporal logic. We explain here the steps required to go from the original algorithm to a working infrastructure capable of monitoring an existing distributed application producing millions of log entries per day. The main… (More)