Bitcoin, being the most successful cryptocurrency, has been repeatedly attacked with many users losing their funds. The industry's response to securing the user's assets is to offer tamper-resistant hardware wallets. Although such wallets are considered to be the most secure means for managing an account, no formal attempt has been previously done to identify, model and formally verify their properties. This paper provides the first formal model of the Bitcoin hardware wallet operations. We identify the properties and security parameters of a Bitcoin wallet and formally define them in the Universal Composition (UC) Framework. We present a modular treatment of a hardware wallet ecosystem, by realizing the wallet functionality in a hybrid setting defined by a set of protocols. This approach allows us to capture in detail the wallet's components, their interaction and the potential threats. We deduce the wallet's security by proving that it is secure under common cryptographic assumptions, provided that there is no deviation in the protocol execution. Finally, we define the attacks that are successful under a protocol deviation, and analyze the security of commercially available wallets.

Purpose The supervisory stress test evaluates the capital adequacy and profit-generation capacity of systemic banking institutions under baseline and adverse macroeconomic scenarios. This study aims to assess the financial and informational role of European stress tests and substantiate the impact of their disclosures by examining the EU-wide 2018 stress test vis-à-vis the EU-wide 2021 stress test in terms of how and to what extent the stock prices of the stress-tested banks have been affected. Design/methodology/approach This study applies standard event study methodologies to evaluate the reactions of market participants during the EU-wide 2018 and 2021 stress test exercises. We examine several “large” events in both the exercises for a selected sample of European banks. Findings The results of our event study analysis show that the EU-wide 2018 and 2021 stress tests come subsequent to considerable abnormal price movements. The announcement of stress test results triggered tangible investor reactions, indicating the informational value of stress tests in reducing bank opacity. This supervisory “toolkit” is considered extremely important, as it provides meaningful insights to the supervisors of the banking institutions and the market stakeholders by improving the transparency of the financial sector, allowing them to segregate banks more effectively. Originality/value This study constitutes one of the earliest attempts to shed light on the financial and information role of the European supervisory stress tests by comparing the EU-wide 2018 and the EU-wide 2021 stress test exercises. Moreover, it provides concrete empirical evidence and qualitative analysis to explore certain aspects of the European and US stress tests.

Le Moyen-Orient est profondément et durablement déstabilisé sans que des perspectives claires ne se dégagent aujourd’hui. Certes, les Occidentaux ont leur part de responsabilité mais les États de la région doivent admettre qu’ils doivent revoir leur politique et accepter l’émergence d’une société civile pour éviter le chaos.

Le paysage infernal, celui du pays des morts tel que l’imaginaient les Grecs anciens et les Romains est un élément très important de la littérature fantastique et du roman de guerre. Le thème de la mort constitue le pivot du récit dans ces deux contextes littéraires, si différents. La lecture des extraits des textes étudiés nous révèle l’importance de l’utilisation de l’antithèse et de la négation d’un point de vue stylistique. L’univers chthonien et nocturne, évoqués par H.P. Lovecraft et Claude Simon, les auteurs étudiés, symbolisent aussi les profondeurs psychiques. La notion d’intemporalité nous rapproche du rêve ou de la condition chaotique. L’écriture à la première personne dans les œuvres choisies exprime, par ailleurs, la présence constante de le conscience humaine s’opposant à la monstruosité ou à l’absurdité environnante.