Atomic Swapping Bitcoins and Ethers

International audienceBlockchains interoperability is one of the hardest problems to be solved in the nowadays blockchain ecosystem that contains thousands of different blockchains. This paper focuses on swapping assets from a blockchain to another without a trusted third party. One recent scheme for atomically swapping assets, Atomic Cross Chain Swap (ACCS), has been formally analyzed in [2]. This paper proposes an implementation of an ACCS between the two most valued crypto-currencies today: Bitcoin and Ether

A protocol language for smart contracts

Tese de mestrado, Engenharia Informática (Engenharia de Software), 2021, Universidade de Lisboa, Faculdade de CiênciasSmart contracts are immutable automated scripts published on distributed ledgers (such as blockchains) that express a set of procedures to be followed by the participants. These contracts have gained popularity, yet breaches in their reliability and security linger on, with some of these exploits causing losses of millions of USD. Examples of attacks are the DAO and the parity wallet hack. Among the vulnerabilities in smart contracts, we concentrate on faults rooted in out-of-order interactions with contract endpoints. We propose SmartScribble, a protocol language to specify patterns of interaction between users and endpoints, allowing developers to implement correctby-construction contracts. From a protocol description, the compiler generates a smart contract that the programmer should complete with the relevant business logic. SmartScribble’s syntax is heavily inspired in Scribble, even if it covers only a fragment of the latter language and adapts it to fit the blockchain environment. Generated contracts rely on integrated finite state machines to control endpoint invocations by detecting unexpected interactions and ensuring that they have no potentially harmful side effects. As a proof of concept, we target Plutus, a smart contract programming language from the Cardano blockchain. Initial results point to secure contracts that enforce correct interaction patterns and exhibit a decrease of 75% in the size of the code that developers must write. Performance-wise, contracts generated with SmartScribble are on par with to those implemented by experts that also use a state machine

Privacy in Cross-border Digital Currency. A Transatlantic Approach

This paper is one of four publications launched at the inaugural Frankfurt Forum on US-European GeoEconomics held in Germany from September 27 – 29, 2022. Co-hosted by the Atlantic Council GeoEconomics Center and Atlantik-Brücke, the Frankfurt Forum anchors critical work on transatlantic economic cooperation. The war in Ukraine, and the G7 response, reminded the world of the impact of transatlantic coordination. As part of the Frankfurt Forum, this new research aims to advance transatlantic dialogue from crisis response to addressing the key economic issues that will underpin the US-EU partnership over the next decade. The goal of the Frankfurt Forum is to deliver a blueprint for cooperation in four key areas: digital currencies, monetary policy, international trade, and economic statecraft