International Association
for Cryptologic Research

Bitcoin script cannot easily access and store state information onchain without an upgrade such as BIP-347 (OP_CAT); this makes performing general (stateful) computation on Bitcoin impossible to do directly. Despite this limitation, several approaches have been proposed to bypass it, with BitVM being by far the most production-ready of them. BitVM enables fraud-proof-based computation on Bitcoin, relying on a $1$-out-of-$n$ honesty assumption.

This left the question of whether it is possible to achieve computation under the same honesty assumption without requiring onlookers to ensure validity through fraud proofs. In this note, we answer this question affirmatively by introducing ColliderVM, a new approach for performing computation on Bitcoin today. Crucially, this approach eliminates some capital inefficiency concerns stemming from reliance on fraud proofs.

For our construction, a key point is to replace the Lamport or Winternitz signature-based storage component in contemporary protocols with a hash collision-based commitment. With it, we estimate that the Bitcoin script length for STARK proof verification is drastically shorter than that for other pairing-based proof systems used today in applications.