Formally based semi-automatic implementation of an open security protocol

International audienceThis paper presents an experiment in which an implementation of the client side of the SSH Transport Layer Protocol (SSH-TLP) was semi-automatically derived according to a model-driven development paradigm that leverages formal methods in order to obtain high correctness assurance. The approach used in the experiment starts with the formalization of the protocol at an abstract level. This model is then formally proved to fulfill the desired secrecy and authentication properties by using the ProVerif prover. Finally, a sound Java implementation is semi-automatically derived from the verified model using an enhanced version of the Spi2Java framework. The resulting implementation correctly interoperates with third party servers, and its execution time is comparable with that of other manually developed Java SSH-TLP client implementations. This case study demonstrates that the adopted model-driven approach is viable even for a real security protocol, despite the complexity of the models needed in order to achieve an interoperable implementation

Stock Exchange Markets for New Ventures

In Canada, a venture stock market lists micro-capitalization firms that are at a pre-revenue stage, and competes with both formal and informal venture capital (VC). This market provides a higher rate of return and is able to provide seven times more new listings to the main exchange than the VC market. We do not evidence post-graduation underperformance, and indeed, new listings on a main exchange can succeed even if they originate from a public venture market. Our results do not support the theoretical arguments that confer specific advantages on the VCs with regard to screening, monitoring and exiting new ventures. Au Canada, un marché boursier de capital de risque inscrit des entreprises à très faible capitalisation, avant même qu’elles ne rapportent des revenus. Ce marché est en concurrence directe avec le capital de risque institutionnel et informel. Le taux de rendement de ce marché boursier est supérieur à celui du capital de risque, et ce marché amène sept fois plus d’entreprises au marché principal, par « graduation », que ne le fait le capital de risque à la suite d’émissions initiales. Nous n’observons aucune performance anormale négative à la suite des graduations. Nos résultats indiquent que le capital de risque canadien ne semble pas disposer des avantages que la théorie attribue généralement à ce type d’investisseurs en matière de sélection des projets, de supervision ou encore de capacité de disposition des placements.public venture capital, start-up, graduation, success rate, stock exchange, capital de risque, démarrage, graduation, marché boursier