Steven Roose presents Ark, a promising Bitcoin protocol and how Roose’s company, Second, is developing on Ark. Ark eliminates channel management while remaining non-custodial. Roose explains the mechanics of shared UTXOs, virtual transactions, and the atomic swapping process that makes it all work. He dives into the protocol’s evolution from CLARK to IRC (a non-interactive version), highlighting how CTV covenants could dramatically improve mobile user experience by reducing interaction requirements. The presentation explores practical applications including lightning interoperability, mass payouts, and transaction reassurance, showcasing how Arc could bring Bitcoin payments to mobile users with minimal friction.
This presentation was recorded live at 2025’s OPNEXT, the Bitcoin scaling conference. For more info, visit opnext.dev. OPNEXT livestream and VODs are made possible by Taproot Wizards.
To watch the full library of OPNEXT 2025 content, be sure to check out our YouTube channel!
Subscribe to the newsletter! https://newsletter.blockspacemedia.com
# Notes:
– Arc uses shared UTXOs instead of channels
– Mobile implementation faces challenges on iOS
– Non-interactive version could solve DOS issues
– Aims for end-of-year mobile wallet integration
– Protocol works with 4-branch trees (not binary)
– CTV would enable mass payouts to many users
