The developers of Bitcoin sidechain technology, BitVM, have unveiled the second version of the system, introducing new permissionless challenge features and reducing transaction complexity.

Updates in BitVM2

On August 15, Alexei Zamyatin, co-founder of Build on Bitcoin, announced that the updated version improves system security by allowing anyone to challenge transactions. This reduces the on-chain transactions to just three for dispute resolution. According to the BitVM2 whitepaper, the new version requires no consensus changes within the Bitcoin network, enabling the design of entirely new classes of applications on the blockchain. Quote from the BitVM2 whitepaper: “To guarantee liveness, we only require one active rational operator (while the others can be malicious). Any user can act as a challenger, facilitating permissionless verification of the protocol.”

BitVM Bridge Design

The BitVM bridge design, described as 'the most secure BTC bridge to date,' employs a 1-of-n security model, allowing anyone to challenge and prevent unauthorized transactions. This contrasts with the traditional t-of-n multisig approach which relies on an honest majority.

Solving Scalability Challenges

Authored by Robin Linus, Alexei Zamyatin, Lukas Aumayr, Andrea Pelosi, Zeta Avirikoti, and Matteo Maffei, the whitepaper notes that nearly all existing Bitcoin bridges rely on multi- or threshold signature schemes, where a group of t-of-n signers is entrusted with safeguarding Bitcoin. Although some bridges employ economic security through collateralization, the authors state that these designs face scalability challenges due to high capital requirements and have thus achieved limited adoption in practice.

First unveiled in October 2023, BitVM aims to redefine Bitcoin by enabling smart contract-like functionalities without transforming it into Ethereum. The project has led to the creation of initiatives like Bitlayer, aimed at advancing layer-2 solutions on the Bitcoin network.

The new BitVM version and bridge design promise significant improvements for the Bitcoin sidechain, addressing scalability and security issues.