BitVMX: A CPU for Universal Computation on Bitcoin

Check out this link for more info: bitvmx.org So, BitVMX is this fresh framework that lets you run any program on Bitcoin using this N-party disputable computation idea from BitVM. It’s designed to support any CPU on Bitcoin, especially a fully compliant RISC-V processor that works with regular compilation tools. The aim here is to build a secure, open-source, and extensible framework that’s been peer-reviewed and isn’t tied to any specific sidechain. This could be a big deal for developing blockchain bridges, oracle aggregators, and verifiers like SNARKs or STARKs. Once BitVMX gets the SNARK verifier up and running, we could see all sorts of new applications on Bitcoin, from ZK-rollups to really wild ideas like Zero Knowledge Contingent Payments, which are basically automated bug bounties for reporting vulnerabilities.

Fantastic! So this basically makes Bitcoin scripts Turing-complete?

RISC-V support? I must say it's rather specific goal. While the technical details go over my head, it's good there's major improvement on preprocessing time and storage space. I recall simple operation using BitVM use over 20KB of data. As reminder, BitVM (the predecessor) already allows turing-complete script. See https://bitvm.org/bitvm.pdf.

The key differences between BitVM1 and BitVMX are the amount of pre-computation required, the transaction space consumed, and more importantly, the complexity of the solution. Regarding pre-computation, BitVM1 requires computing large Merkle trees (2^32 elements in size). BitVMX does not require to compute any Merkle tree. Regarding onchain footprint, in the optimistic case, both BitVM1 and BitVMX require just one multi-signed transaction. But in the pessimistic case, if one of the parties is malicious, then BitVM1 may require more than 250K of virtual bytes (in total between both parties). This is my estimation, not a precise number, because BitVM1 was never finished. In contrast, BitVMX consumes less than 160K of virtual bytes. Also BitVMX can be parametrized to require half the number of interaction rounds compared to BitVM1, at the expense of higher space consumed.  Finally, BitVMX is much simpler. I think anyone will understand it in 10 minutes. While the bitvmx.org site has some information, the first paper will be published just before BTC++ (May 1, '24).

FYI the BitVMX paper is available at https://bitvmx.org There is a Telegram channel for devs and a twitter account for updates.

That's great. Clearly we need to start writing software to support this.