The developer has found a way to expand the capabilities of Bitcoin smart contracts


ZeroSync co-founder Robin Linus introduced the BitVM mechanism to expand the capabilities of smart contracts on Bitcoin without the need to upgrade the network.

According to Linus, the solution allows any computable function to be verified in the protocol while being Turing complete.

The system does not require changes to the consensus rules. Instead of performing calculations on the blockchain, they are simply verified, similar to Optimistic rollups.

BitVM uses a challenge-response protocol, proof of fraud, and Taproot for interaction between prover and verifier.

Linus noted that even running “large programs” would have minimal impact on the network.

“As long as both parties cooperate, they can perform arbitrarily complex calculations off-chain without leaving a trace on the chain. On-chain execution is required only in case of a dispute,” the developer emphasized.

He admitted that the main disadvantage of the proposed model is the limitation of two-way tuning using a prover and a verifier. Another “minus” Linus called is the need for a large amount of off-line computing. These questions are expected to be resolved in further research.

The developer believes that BitVM creates the ability to design more “expressive” contracts in Bitcoin, which are initially reduced to basic operations.

He named gaming applications such as chess, Go or poker, as well as verifying the reliability of evidence, as potential applications for the solution. The mechanism also makes it possible to connect Bitcoin to other networks, create a prediction market and emulate new operation codes.

“This is probably the most exciting discovery in the history of Bitcoin scripts. It seems to open almost all doors and give us access to covenants, sidechains and features like Liquid or EVM, all at the same time, without the need for forks. I can’t wait to publish my demo,” wrote programmer under the pseudonym Super Testnet.

Columnist Sam Parker notedthat BitVM allows Bitcoin to be Turing complete like any other chain.

Paradigm researcher Dan Robinson disagreed with this opinion. He believes that the mechanism realizes only functional completeness.

CEO of the Ordinals platform Bioniq Bob Bodily pointed out that the main advantage of BitVM is that the mechanism provides a ready-made addition to Bitcoin programmability without updating. However, the expert warned:

“This is not a panacea. No, BitVM is not as good as EVM – slower, more expensive and more complex.”

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

Blockstream CEO Adam Back statedthat despite the hype, the solution is “essentially a generalization of a two-sided game” and may hit “pragmatic scalability limits.” Linus disputed his claims.

Let us recall that in March ZeroSync announced the creation of tools for scaling Bitcoin using zero-knowledge proofs (ZKP).

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

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