I work at the intersection of blockchain security, programming languages, and formal methods. My background combines smart contract auditing, formal verification, smart contract development, and academic research, with a particular interest in applying rigorous methods to real-world systems.
Spearbit (Recurring Freelance)
2024 - 2026 · Lead Security Researcher
- Performed smart contract and protocol security reviews through the Spearbit network.
- Contributed audit work for blockchain clients across DeFi and infrastructure.
- Worked alongside other senior security researchers on adversarial review and vulnerability analysis.
Decidable OU
2020 - 2026 · Smart Contract Developer
- Independent smart contract development and auditing, with a focus on NFTs, token contracts, and token vesting systems.
- Built and reviewed contracts for clients in the blockchain and digital asset space.
- Used Decidable as my consulting vehicle for blockchain engineering and security work.
Runtime Verification, Inc. (Recurring Freelance)
2019 - 2024 · Formal Verification Engineer -> Senior Formal Verification Engineer (since 2021)
- Primary developer of KWasm, a formal semantics of WebAssembly in the K framework.
- Built tooling intended for formal verification of blockchain systems running Wasm-based smart contracts.
- Worked on executable semantics and verification-oriented infrastructure for blockchain use cases.
- From 2021 onward, worked as an Ethereum and DeFi auditor, often acting as the sole auditor on an engagement or helping train newer auditors.
- Led Wasm-related workstreams and supported the development of formal verification tooling used in audits.
- Contributed formal methods expertise to smart contract security reviews and protocol analysis.
- Since 2024, have continued to act as an advisor on technical direction and strategy.
Jun - Sep 2017 · Software Engineering Intern, Zurich, Switzerland
- Extended Calendar Interop for integrating Outlook Calendar and Google Calendar.
- Worked with Java, Python, and XML.
Jun - Oct 2016 · Software Engineering Intern, Stockholm, Sweden
- Built experimental features in WebRTC Audio.
- Worked with C++, Python, JavaScript, and Git.
Varbi
May - Oct 2015 · Software Engineer, Trollhattan, Sweden
- Built integrations between Excel and a PHP/MySQL-based system.
- Improved report rendering performance by roughly five times through algorithmic improvements.
- Worked with PHP, MySQL, JavaScript, and Git.
Doost AB
2013 - 2014 · Communication Consultant, Malmo, Sweden
- Copywriting.
- Value-based leadership workshops.
- Brand strategy work.
- Sales.
Security Audits
- Selected audit work is available at Cantina.
- Reviewed systems and smart contracts across DeFi, infrastructure, and application-layer crypto projects.
KWasm
- KWasm is a formal semantics of WebAssembly in the K framework.
- Built as a basis for formal verification of Wasm smart contracts and related blockchain applications.
- Also contributed the EWasm embedding for the Ethereum-Wasm effort.
%quiz and KNock
- Built a property testing framework for Urbit called %quiz.
- Built formal-semantics-related tooling around Nock, the VM and development languages for Urbit.
- Worked on connecting semantics-driven reasoning with testing-oriented tools for the Urbit ecosystem. The Urbit project petered out before we could finish.
Chalmers University of Technology
Master's Degree in Computer Science, Algorithms, Languages and Logic · 2018 - 2020
- Graduated as valedictorian.
- Thesis: Formally Verifying WebAssembly with KWasm - Towards an Automated Prover for Wasm Smart Contracts
- Coursework included advanced programming language concepts such as DSLs, type engineering, parallel functional programming, and compiler construction.
- Mathematics and theory coursework included cryptography, abstract algebra, formal logic, game theory, neural networks, and stochastic optimization.
The University of Tokyo
Exchange Master's Studies · 2017 - 2018
- Coursework included blockchain, programming language implementation, algorithms, security, physics simulation, and Japanese.
Chalmers University of Technology
Bachelor's Degree in Software Engineering · 2014 - 2017
- Graduated as valedictorian.
- Thesis: The CakeML Compiler Explorer: Visualizing how a verified compiler transforms expressions
- Coursework included programming, algorithms, formal languages, interface design, and agile project management.
A Proposal of Blockchain-Based Electronic Voting System
- Adiputra, C. K., Hjort, R., Sato, H. (2018)
- 2018 Second World Conference on Smart Trends in Systems, Security and Sustainability (WorldS4)
The CakeML Compiler Explorer: Tracking Intermediate Representations in a Verified Compiler
- Hjort, R., Holmgren, J., Persson, C. (2018)
- International Symposium on Trends in Functional Programming
Invited Talks And Appearances
- Ep. 39 Rikard Hjort from Runtime Verification - Whiteboard Series with NEAR Protocol
- KWasm: Formal Verification for fun and profit - Science! by Infotiv
- K Framework for Smart Contract Formal Verification - ETH Warsaw
- Real-world Formal Verification of Smart Contracts using the K Framework - IEEE International Conference on Blockchain and Cryptocurrency 2020
- Introduction to the K Framework and KSolidity - Solidity Summit 2020
- Formal Verification and Smart Contracts - chat with Rikard Hjort - Blockchain PR Podcast, 2020
- Introduction to K-Michelson - Tezos Smart Contracts: Programming Languages and Formal Verification Workshop, Paris 2020
- The future of KEwasm: Lightning talk - Devcon 2019, Osaka
- KWasm - Wasm on the Blockchain, Berlin 2019
- Hur funkar blockchain? En introduktion for programmerare. - Chalmers University of Technology, 2019
- K framework and WebAssembly to KWasm - Chalmers University of Technology, 2019
Thesis And Degree Supervision
- Burak Bilge Yalcinkaya - A Formal Semantics for Javalette in the K framework, 2022, Chalmers University of Technology, M.Sc. Computer Science, Algorithms, Languages and Logic
- Katherine Hoy - Continuous Narratives in Kinetic Theater: A Study on the History of Puppetry in Popular Theater and Performance Space Defined Through the Use of Automaton-Marionettes, 2022, University of Europe for Applied Sciences - Art and Design, M.A. Media Spaces
- Anton Ahl - KHoon: A Formal Semantics of Hoon in the K Framework, 2023, Chalmers University of Technology, M.Sc. Computer Science, Algorithms, Languages and Logic, Chalmers ODR
Awards
- John Ericsson honorary medal, awarded each year to the 6 highest-achieving recent graduates from Chalmers University of Technology.
Community
- Student Union Council
- Chalmers Student Union IT Strategy Committee