Obsidian

Abstract

Blockchain platforms are coming into use for processing critical transactions among participants who have not established mutual trust. Many blockchains are programmable, supporting smart contracts, which maintain persistent state and support transactions that transform the state. Unfortunately, bugs in many smart contracts have been exploited by hackers. Obsidian is a novel programming language with a type system that enables static detection of bugs that are common in smart contracts today. Obsidian is based on a core calculus, Silica, for which we proved type soundness. Obsidian uses typestate to detect improper state manipulation and uses linear types to detect abuse of assets. We integrated a permissions system that encodes a notion of ownership to allow for safe, flexible aliasing. We describe two case studies that evaluate Obsidian's applicability to the domains of parametric insurance and supply chain management, finding that Obsidian's type system facilitates reasoning about high-level states and ownership of resources. We compared our Obsidian implementation to a Solidity implementation, observing that the Solidity implementation requires much boilerplate checking and tracking of state, whereas Obsidian does this work statically.

EOLANG and $φ$-calculus

“…Later it was extended by Jagannathan et al [55] to support nested and multi-threaded transactions. Featherweight Java is used in formal languages such Obsidian [25] and SJF [92].…”

Pliers

“…We avoided inheritance, since we wanted to avoid the fragility that results [59]. For a full description of the language, please refer to Coblenz et al [26]. However, Figure 1 shows some of the key features of the final version of Obsidian using the example of a tiny vending machine (TVM).…”

“…In addition to doing two case studies to evaluate expressiveness [26], we conducted a lab study to answer two research questions relating to our comparison question in Section 1 ("How can we compare multiple language designs to see which are more effective for users? "):…”

“…Quantitative studies typically involve fairly constrained tasks, but we can hope to obtain statistical significance in a comparison between two different designs. Finally, although this article does not focus on our case study work, we also used case studies to address questions of expressiveness: elucidating what happens when the language is used to solve a larger programming problem, which cannot be completed in a single-session user study; for more information, see Coblenz et al [24] and Coblenz et al [26].…”

Securing smart contracts with formal verification and automated program repair

“…In fact, Solidity encourages to model smart contracts as state machines [4]. Some recently proposed smart contract languages, including Bamboo [2] and Obsidian [80], adopt a state-oriented programming paradigm, which provides better security guarantees by making state transitions explicit. In the context of verification, depending on the properties of interest, a wide range of choices exist for formalizing smart contracts as state-transition systems.…”