Computing on Bitcoin #107
September 18, 2026 - Week 38
Welcome to a new edition of Computing on Bitcoin News.
Here's our curated selection of this week's most relevant developments.
Let's dive into this week's highlights.
Robin Linus introduces BitVM-448, a covenant-based BitVM3 bridge design using OP_TEMPLATEHASH to enable non-interactive deposits and simplify assertion bonds, addressing key limitations of current BitVM3 bridges.
robinlinus.com
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BitVM-448: Covenant-Based BitVM3 Bridges
This note sketches BitVM-448, a BIP-448-based BitVM3 bridge using OP_TEMPLATEHASH covenants and OP_CHECKSIGFROMSTACK for deleted-key recursion. Native template covenants replace per-deposit pre-signed transactions, removing the per-deposit cosigner set from bridge safety and allowing non-interactive deposits into prepared slots. The operator's per-attempt bond is moved into the asserted UTXO, so an invalid assertion can return the reserve to the bridge while burning the bond, without a sibling-input covenant.
A new article maps Bitcoin layer 2 and payment rail designs, including Lightning, Liquid, sBTC, and BitVM bridges, comparing them by who can freeze, censor, or lose the underlying bitcoin.
proofoftalk.io/blog
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Bitcoin beyond holding: payment rails, layer 2s and programmable value
Lightning, Liquid, sBTC, BitVM bridges, wrapped tokens and bitcoin-backed loans each ask a holder to trust someone other than Bitcoin's own rules. This is a sourced, dated account of who that is in each case.
A new report compares Rootstock and Stacks as Bitcoin DeFi platforms, covering their peg designs, security models, yield mechanisms, and history, while noting newer BitVM-based designs pursuing more trust-minimized pegs.
hoge.gg
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Stacks vs Rootstock: Bitcoin's Oldest DeFi Bet in 2026
Two years before Ethereum shipped its first optimistic rollup, and long before anyone talked seriously about running stablecoins on Bitcoin rails, two teams set out to answer the same awkward question: can the most valuable, most conservative blockchain do anything other than sit still? Rootstock went live on 2 January 2018 as a smart-contract sidechain merge-mined by Bitcoin's own miners, according to research from Spark.
That wraps up this week's edition of Computing on Bitcoin News. We hope you found it useful, and we'll be back next week with more developments from across the Bitcoin Computing ecosystem.
The Fairgate Team