Yuval Kogman Joins Payjoin Foundation as Advisor

Spiral Bitcoin Wizard and longtime Bitcoin privacy developer Yuval Kogman joins Payjoin Foundation as the first Advisory Board member. He draws on more than two decades of programming experience. Few others can boast Yuval's dedication to the Bitcoin privacy niche. He is perhaps best known for his work developing the WabiSabi DoS prevention protocol. His subsequent whistleblowing of privacy vulnerabilities in CoinJoin implementations, including those touting WabiSabi integration, demonstrates his commitment to the underlying principles.

Prior to his current focus on Payjoin, Yuval had already been working on a decentralized, multiparty transaction batching protocol. We have joined forces to develop this next-generation batching and deliver it via Payjoin Dev Kit.

For those still uninitiated, Payjoin is the simplest way to build two-party batched transactions. Rather than convincing a user to take some extra steps to try and "gain" privacy (by joining a CoinJoin round, triggering a swap, etc.), payjoin automates a privacy-preserving interaction that runs in the background when a user generates an address or hits "send" in their wallet. By automating the creation of a batched transaction between one entity paying another, payjoin gives both entities a chance to more efficiently spend coins and protect all who use Bitcoin from third-party surveillance's most useful heuristic for identifying balances and relationships of users without their consent.

The multiparty version we imagine lets transfers from Alice to Bob to Charlie cut through one transaction. Such an interactive protocol can be more efficient than old-school payment batching, and makes second-person privacy possible: we envision that people making transfers to one another using such a mechanism will produce transactions where neither party knows the others' addresses while preserving a familiar user experience.

Yuval has been an informal advisor to the project for a number of years, helping us shape the Payjoin Dev Kit API, troubleshoot reliability issues, and design BIP 77 Async Payjoin to address former barriers to adoption. While co-authoring the Async Payjoin specification together, he attended to nitty gritty details including QR code scanning reliability, message uniformity, and IP address metadata privacy. Preventing leaks of both private information and potential failure is what keeps the Payjoin experience dependable.

More than that, Yuval is a friend to the team. He demands positive-sum solutions where everybody wins and invests heavily in budding talent. He is uncompromising when it comes to his values, so his advice keeps us focused on the mission.

Spiral's unwavering support for the Payjoin mission began in 2023, when they initially extended me a grant to lead Payjoin development. Since then, they have funded multiple developers, including Spacebear, our team's integrations expert. Payjoin also owes a debt of gratitude to Spiral for their support of neighboring ecosystem projects. For example, we depend on rust-bitcoin for our core bitcoin types, and Bitcoin Dev Kit for pioneering a foreign language bindings strategy that makes deploying our code to various programming languages possible. Thank you.

We can't wait to see where Yuval's help takes us from here. Thank you Yuval and Spiral for your faith in the mission and the sacrifices you are making to realize it.