Modeling Bitcoin Contracts by Timed Automata

Bitcoin is a peer-to-peer cryptographic currency system. Since its introduction in 2008, Bitcoin has gained noticeable popularity, mostly due to its following properties: (1) the transaction fees are very low, and (2) it is not controlled by any central authority, which in particular means that nobody can "print" the money to generate inflation. Moreover, the transaction syntax allows to create the so-called contracts, where a number of mutually-distrusting parties engage in a protocol to jointly perform some financial task, and the fairness of this process is guaranteed by the properties of Bitcoin. Although the Bitcoin contracts have several potential applications in the digital economy, so far they have not been widely used in real life. This is partly due to the fact that they are cumbersome to create and analyze, and hence risky to use. In this paper we propose to remedy this problem by using the methods originally developed for the computer-aided analysis for hardware and software systems, in particular those based on the timed automata. More concretely, we propose a framework for modeling the Bitcoin contracts using the timed automata in the UPPAAL model checker. Our method is general and can be used to model several contracts. As a proof-of-concept we use this framework to model some of the Bitcoin contracts from our recent previous work. We then automatically verify their security in UPPAAL, finding (and correcting) some subtle errors that were difficult to spot by the manual analysis. We hope that our work can draw the attention of the researchers working on formal modeling to the problem of the Bitcoin contract verification, and spark off more research on this topic

Assurance Cases in Model-Driven Development of the Pacemaker Software

We discuss the construction of an assurance case for the pace-maker software. The software is developed following a model-based technique that combined formal modeling of the system, systematic code generation from the formal model, and measurement of timing behavior of the implementation. We show how the structure of the assurance case reflects our development approach

Fast algorithms for handling diagonal constraints in timed automata

A popular method for solving reachability in timed automata proceeds by enumerating reachable sets of valuations represented as zones. A na\"ive enumeration of zones does not terminate. Various termination mechanisms have been studied over the years. Coming up with efficient termination mechanisms has been remarkably more challenging when the automaton has diagonal constraints in guards. In this paper, we propose a new termination mechanism for timed automata with diagonal constraints based on a new simulation relation between zones. Experiments with an implementation of this simulation show significant gains over existing methods.Comment: Shorter version of this article to appear in CAV 201

Globalization as the “Pulping” of Landscapes: Forestry Capitalism’s North-South Territorial Accumulation

The article presents the findings of a long-term incorporated comparison of forestry capitalism's globalization process. Primary data was collected by participant observation in pulp investment areas in Brazil between 2004 and 2011 and semi-structured interviews with key industry personnel, particularly in Finland. It is argued that the key cyclic change in industrial forestry from innovation–capitalization to material–territorial accumulation explains why and how the industry has globalized to the south via industrial tree plantations. The interlinked northern (Finnish) and southern (Brazilian) cases reveal that industry trajectories are influenced by who controls the supply chains of commodities. The findings are relevant for theorizing about the globalization of natural resource exploitation sectors. Changes in agrarian political economies and agency of state, business, and social movement actors—that is, socio-ecological relations and landscapes—help to explain how and why national and global capitalism and its developmental–environmental impacts are transformed.Peer reviewe

Verifying MARTE/CCSL Mode Behaviors Using UPPAAL

International audienceIn the development of safety-critical embedded systems, the ability to formally analyze system behavior models, based on timing and causality, helps the designer to get insight into the systems overall timing behavior. To support the design and analysis of real-time embedded systems, the UML modeling profile MARTE provides CCSL - a time model and a clock constraint specification language. CCSL is an expressive language that supports specification of both logical and chronometric constraints for MARTE models. On the other hand, semantic frameworks such as timed automata provide verification support for real-time systems. To address the challenge of verifying CCSL-based behavior models, in this paper, we propose a technique for transforming MARTE/CCSL mode behaviors into Timed Automata for model-checking using the UPPAAL tool. This enables verification of both logical and chronometric properties of the system, which has not been possible before. We demonstrate the proposed transformation and verification approach using two relevant examples of real-time embedded systems

Automatic generation of provably correct embedded systems

10.1007/978-3-642-34281-3_17Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)7635 LNCS214-22

Modeling longrunning transactions with communicating hierarchical timed automata

Abstract. Long-running transactions consist of tasks which may be executed sequentially and in parallel, may contain sub-tasks, and may require to be completed before a deadline. These transactions are not atomic and, in case of executions which cannot be completed, a compensation mechanism must be provided. In this paper we develop a model of Hierarchical Timed Automata suitable to describe the aspects mentioned. The automaton-theoretic approach allows the verification of properties by model checking. As a case study, we model and analyze an example of long–running transaction.

Modeling of WEST plasmas with reduced Lower-Hybrid model: interplay with transport and parameter optimization

International audienceA heuristic reduced model was developed in METIS [Artaud et al, 2018] for a fast and reliable Lower-Hybrid Heating and Current Drive (LHCD) power and current deposition. Its performance is studied in a stand-alone way through experiments and first-principle modeling comparisons within a WEST database. Its self-consistent evolution is then characterized through an integrated modeling approach incorporating the interplay with transport