Developer finds a way to expand Bitcoin smart contract capabilities

ZeroSync co-founder Robin Linus unveiled the BitVM mechanism to expand Bitcoin’s smart contract capabilities without requiring a network upgrade.

‘Any computable function can be verified on Bitcoin’ https://t.co/Itf9UHos0C pic.twitter.com/CLQv49Ydsg

— robin linus (@robin_linus) October 9, 2023

According to Linus, the solution allows the protocol to verify any computable function, with full Turing completeness.

The system does not require changes to consensus rules. Instead of performing computations on-chain, they are simply verified, similar to Optimistic-rollups.

BitVM uses for interaction between the prover and verifier a request-response protocol, fraud proofs, and Taproot.

Linus noted that even executing ‘large programs’ would have a minimal impact on the network.

‘As long as both parties cooperate, they can perform arbitrarily complex off-chain computations without leaving traces on the chain. On-chain execution is required only in the event of a dispute,’ the developer emphasised.

He identified the main drawback of the proposed model as the limitation of bidirectional configuration with a prover and verifier. Another ‘minus’, Linus said, was the need for a large amount of off-chain computations. These questions are expected to be addressed in subsequent research.

The developer argues that BitVM opens doors to more expressive Bitcoin contracts, which are at heart reducible to basic operations.

Potential use cases include gaming applications like chess, Go or poker, as well as verifying proofs. The mechanism also enables connecting Bitcoin to other networks, creating a prediction market and simulating new operation codes.

‘This is probably the most exciting discovery in the history of Bitcoin scripting. It seems to open virtually all doors and give us access to ковенантам, sidechains and capabilities similar to Liquid or EVM, all at once, without forks. I can\’t wait to publish my demo version,’ wrote the programmer under the alias Super Testnet.

The reviewer Sam Parker noted that BitVM makes Bitcoin effectively Turing complete, like any other chain.

Paradigm researcher Dan Robinson did not share that view. He argues that the mechanism implements only functional completeness.

Bob Bodily, CEO of the Ordinals platform Bioniq, described as the main advantage of BitVM its ready-made augmentation to Bitcoin’s programmability without upgrades. However, the researcher warned:

‘This is not a panacea. No, BitVM is not as good as the EVM — slower, more expensive and more complex.’

BitVM: Everything you need to know (and more…)

BitVM is a new Optimistic Roll Up + Fraud Proof + Taproot Leaf + Bitcoin Script computing paradigm designed by Robin Linus at Zero Sync. They published an excellent white paper this morning reviewed by Super Testnet and Sam Parker… pic.twitter.com/9rjIZZrSSI

— Bob Bodily, PhD ? | #BTC #ETH #ICP (@BobBodily) October 10, 2023

The system also does not address the reliability of bridges to sidechains, he added.

Blockstream chief Adam Back said that despite the hype, the solution ‘is essentially a generalisation of the bidirectional game’ and may run into pragmatic scalability limits. Linus disputed his claims.

In March, ZeroSync announced the creation of tools to scale Bitcoin using zero-knowledge proofs (ZKP).

In October, the project implemented the first client system for the Bitcoin block-header chain based on ZK-STARK.