Software engineer and computer scientist based in Stockholm, Sweden. I lead the open-source work at Glasklar Teknik, a sister company of Mullvad VPN and Tillitis. Some of the topics I’m passionate about include cryptography, Linux, privacy, programming in Bash/C/Go, and transparency logs. The last few years I got into self hosting. The overlap between research, development, and operations is fun.

Off work you will find me reading books, playing boardgames with friends, improving my cooking skills, cruising around on inlines, running, and such.

Project involvement

I am a member of the following projects:

• C2SP: a project that facilitates maintenance of cryptographic specifications using software development methodologies rather than IETF-like consensus.
• Sigsum: a free and open source software project that makes a signer’s key-usage transparent. It can be used as a building block to secure the supply chain and more.
• System Transparency: an open source project that provides a security architecture for bare metal servers. A system’s entire boot chain becomes protected and auditable.
• Tor: a 501(c)(3) US nonprofit that advance human rights and defend online privacy through free software and open networks.
• Witness Network: a community effort that gets transparency logs cosigned.

Selected software

I develop and maintain software on my free time. You might be interested in:

• silentct: a Certificate Transparency monitor that filters out the noise.
• onion-csr: a tool to domain-validate onion addresses with CAs.

Selected publications

I don’t publish much papers these days, but here’s an aging selection:

• Rasmus Dahlberg. On Certificate Transparency Verification and Unlinkability of Websites Visited by Tor Users. PhD thesis, Karlstad University (2023)
• Rasmus Dahlberg and Tobias Pulls. Timeless Timing Attacks and Preload Defenses in Tor’s DNS Cache. USENIX Security (2023)
• Rasmus Dahlberg, Tobias Pulls, Tom Ritter, and Paul Syverson. Privacy-Preserving & Incrementally-Deployable Support for Certificate Transparency in Tor. PETS (2021)
• Tobias Pulls and Rasmus Dahlberg. Website Fingerprinting with Website Oracles. PETS (2020)
• Tobias Pulls and Rasmus Dahlberg. Steady: A Simple End-to-End Secure Logging System. NordSec (2018)

Contact

Feel free to reach out on email or other platforms as you see fit.