Jouez à Faire Consensus Avec MITTEN (démonstration)

National audienceCet article présente Mitten, un outil pour décrire finement et jouer des scénarios sur une implémentation de Tenderbake-le prochain protocole de consensus à la pBFT de la blockchain Tezos. Mitten est paramétrable pour filtrer et examiner les messages selon des scénarios particuliers écrits dans un DSL construit sur OCaml. Grâce à Mitten, nous avons pu écrire et simuler des scénarios subtils pour reproduire des comportements difficilement atteignables en temps normal. Nous avons également pu simuler des situations permettant d'exhiber des bugs dans l'implémentation en cours et de tester des correctifs proposés

AltGr-Ergo, a Graphical User Interface for the SMT Solver Alt-Ergo

Due to undecidability and complexity of first-order logic, SMT solvers may not terminate on some problems or require a very long time. When this happens, one would like to find the reasons why the solver fails. To this end, we have designed AltGr-Ergo, an interactive graphical interface for the SMT solver Alt-Ergo which allows users and tool developers to help the solver finish some proofs. AltGr-Ergo gives real time feedback in order to evaluate and quantify progress made by the solver, and also offers various syntactic manipulation options to allow a finer grained interaction with Alt-Ergo. This paper describes these features and their implementation, and gives usage scenarios for most of them

Alt-Ergo 2.2

International audienceAlt-Ergo is an SMT solver jointly developed by Université Paris-Sud and the OCamlPro company. The first version was released in 2006. Since then, its architecture has been continuously adapted for proving formulas generated by software development frameworks. As type systems with polymorphism arise naturally is such platforms, the design of Alt-Ergo has been guided (and constrained) by a native-and non SMT-LIB compliant-input language for a polymorphic first-order logic. In this paper, we present the last version of Alt-Ergo, its architecture and main features. The main recent work is a support for a conservative polymorphic extension of the SMT-LIB 2 standard. We measure Alt-Ergo's performances with this new frontend on a set of benchmarks coming from the deductive program verification systems Frama-C, SPARK 2014, Why3 and Atelier-B, as well as from the SMT-LIB benchmarks library

Formally Documenting Tenderbake

International audienceIn this paper, we propose a formal documentation of Tenderbake, the new Tezos consensus algorithm, slated to replace the current Emmy family algorithms. The algorithm is broken down to its essentials and represented as an automaton. The automaton models the various aspects of the algorithm: (i) the individual participant, referred to as a baker, (ii) how bakers communicate over the network (the mempool) and (iii) the overall network the bakers operate in. We also present a TLA+ implementation, which has proven to be useful for reasoning about this automaton and refining our documentation. The main goal of this work is to serve as a formal foundation for extracting intricate test scenarios and verifying invariants that Tenderbake's implementation should satisfy

Jouez à Faire Consensus Avec MITTEN (démonstration)

National audienceCet article présente Mitten, un outil pour décrire finement et jouer des scénarios sur une implémentation de Tenderbake-le prochain protocole de consensus à la pBFT de la blockchain Tezos. Mitten est paramétrable pour filtrer et examiner les messages selon des scénarios particuliers écrits dans un DSL construit sur OCaml. Grâce à Mitten, nous avons pu écrire et simuler des scénarios subtils pour reproduire des comportements difficilement atteignables en temps normal. Nous avons également pu simuler des situations permettant d'exhiber des bugs dans l'implémentation en cours et de tester des correctifs proposés