BitVM: a Bitcoin (BTC) Rollup that Could Compete with Ethereum (ETH) Rollups?

Contrary to what some people might believe, innovation on Bitcoin knows no bounds. The latest one is BitVM, a second-layer solution envisioned by Robin Linus that could bring complex smart contracts to Bitcoin. Still in the concept stage, how could the Bit Virtual Machine function?

11th October 2023
3 minutes to read
This article is a translation of an article from Cryptoast.fr, which you can find here.

What innovation does BitVM bring?

Still in the idea stage, BitVM, or Bit Virtual Machine, is based on a fundamental concept: the ability to express "Turing Complete" contracts on Bitcoin without altering the network's consensus rules.

In other words, BitVM brings the possibility of creating various smart contracts on the Bitcoin blockchain while preserving its integrity.

A Turing Complete smart contract is a type of intelligent contract capable of executing a wide range of computations and solving various problems, offering great flexibility in the operations it can perform on a blockchain.

BitVM relies on a "trust but verify" principle, where participants make claims that are then verified by other individuals. This system expands the capabilities of Bitcoin, potentially revolutionizing the management of smart contracts on this blockchain and off-chain computations.

BitVM has the capability to create a new space for the development of more complex smart contracts on Bitcoin.

A Second Layer on Bitcoin Similar to Ethereum's Optimistic Rollups (ETH)

Similar to Optimistic Rollups like Optimisum (OP) or Arbitrum (ARB) and the MATT proposal (Merkelize All The Things), BitVM is based on fraud proofs and a "challenge-response" protocol.

The underlying primitives are relatively simple, primarily relying on hashlocks, timelocks, and large Taproot trees.

The prover engages in the program bit by bit, but verifying all of this on the chain would be too computationally expensive. Thus, the verifier performs a sequence of carefully crafted challenges to succinctly refute a false claim made by the prover.

To avoid disputes between the two parties, the challenge-response protocol aims to verify the validity of a proof. This protocol allows the verifier to challenge the prover and compel them to reveal the authenticity of a proof.
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What are the next development steps for BitVM?

BitVM opens the door to a multitude of diverse applications for the Bitcoin blockchain. However, it is still in its early stages and remains at a conceptual stage. Further research will be needed to fully exploit its potential and eventually achieve deployment.

The crucial next steps involve finalizing the design of BitVM and developing Tree++, a high-level programming language specially designed to write and debug Bitcoin smart contracts.

It is important to note that, as stated in Robin Linus's document, BitVM scripts are currently limited to a size of 4 MB. This limit could restrict the complexity of deployed smart contracts.

Between the Drivechain, Runes, and BitVM projects, recent months have shown that the Bitcoin developer community is much more active than it may seem. Innovations continue to shape the future of Bitcoin.

The team working on BitVM development has already received 0.18 BTC in donations, equivalent to about $5,000. If you also wish to contribute financially to the project, you can make donations to the following address: bc1qf5g6z0py2t3t49gupeqrlewga0qz2etalu4xf9.

We will closely follow BitVM developments and keep you informed of future advancements.
Source : BitVM: Compute Anything on Bitcoin