BitVM
Also · BitVM2 · Fraud proof · Optimistic verification
BitVM is a technique to verify arbitrary computation on Bitcoin without changing its rules. A prover claims a result, a verifier can challenge it, and only a fraud ends up on-chain.
Proposed by Robin Linus in 2023, BitVM is not a chain and not a token. It is a way to settle a dispute about a computation using nothing but existing Bitcoin script, hashlocks, timelocks and Taproot trees. The computation runs off-chain. A prover commits to its result. If a verifier disagrees, a challenge-response game forces the prover to reveal the steps until a contradiction can be shown on-chain, in a handful of transactions.
Its first use is bridges. A rollup such as Citrea can let BTC in and out with the guarantee that 1 honest watcher is enough to stop a fraudulent withdrawal. BitVM2 made challenges permissionless and far cheaper than the original design. The delays inherent to dispute windows and the size limits of Bitcoin script remain its constraints.
In French · BitVM
