A surprising proposal that's already generating a lot of buzz, called " BitVM ," could potentially transform the Bitcoin ecosystem. Recently announced by developer Robin Linus , who currently works at ZeroSync , this proposal offers exciting prospects for developing Bitcoin applications using what's known as Zero Knowledge Proof.
Thus, BitVM would make it possible to introduce virtually any arbitrary calculation into the Bitcoin ecosystem that would be executed off-chain. BitVM presents itself as a computing paradigm that allows turing-complete contracts to be expressed on Bitcoin without the need for any modification to the network's consensus rules. To summarize BitVM, we can say that it would be a kind of extension that would allow Bitcoin to do more sophisticated calculations without modifying it.
The most notable aspect of BitVM is that it does not require any changes to the existing Bitcoin consensus. It is also on this precise point that the proposal is seen as interesting by a majority of the Bitcoin community who do not wish to modify the protocol or overwhelm it with transactions perceived as useless. However, other members remain skeptical about the innovation that BitMV entails.
BitVM’s technical proposal
To understand how this works, it's essential to delve into the fundamentals of the proposition. First, it's important to know that computer computation, including Bitcoin transactions, relies on basic logical operations performed by logic gates . Logic gates take binary values (1 or 0) as input and produce a binary value as output based on a simple logical operation. BitVM is based on a logic gate called a "NAND gate," which can perform all the necessary logical operations.
To build a NAND gate in the Bitcoin script, BitVM uses hashlocks and two specific opcodes: OP_BOOLAND and OP_NOT. Hashlocks are fork scripts that can be spent in two different ways, revealing the pre-image of a specific hashlock. One way places a 1 on the stack, while the other places a 0. This allows these hashlocks to be used to "unlock" a bit for the input of a NAND gate.
BitVM then uses OP_BOOLAND and OP_NOT to perform logical operations. OP_BOOLAND produces a 1 as output if both of its inputs are 1s, while OP_NOT inverts the input value (1 becomes 0 and vice versa). By combining these opcodes with the hashlocks, BitVM can perform NAND operations within the Bitcoin script, verifying that the output matches what the user claims.
BitVM's revolutionary aspect lies in its ability to build complex circuits using these NAND gates. Users can break down any arbitrary computation into a series of NAND gates, then encode each gate into a taptree that can be locked with a UTXO. They then pre-sign a series of transactions for a challenge-and-response game that can be executed on-chain.
The idea is that the complex calculation is first verified off-chain, but in case of disagreement or behavior that would be deemed dishonest, it can be challenged on-chain. According to the author, they would be verified in the same way as what is done with "optimistic rollups".
What are the doubts regarding bitVM?
While the proposal seems promising in that it will make it easier to create programs on the Bitcoin network without modifying it, there are still challenges to overcome. Managing the enormous amounts of data generated by BitVM, for example, is a major challenge. Indeed, the cost of managing off-chain data would be absolutely colossal. Some therefore question the merits of such an initiative. This is, for example, what was criticized about the concept of Ordinals , and it is a sensitive point for Bitcoin users.
The other problem that BitMV raises is that this solution only works between two parties (the one who proves and the one who verifies), which limits its usefulness in certain cases. There will certainly be additional research to generalize with several participants.
Final word on the contribution of BitVM
Ultimately, BitVM represents a significant advancement in the Bitcoin field by allowing the introduction of arbitrary calculations while preserving the integrity of the Bitcoin network. Thus, thanks to BitVM, it would be possible to consider more advanced calculations which would only have been possible by performing softforks for example.
Some even go so far as to say that it is the end of altcoins on other blockchains and that everything will now be done on Bitcoin.
Although issues remain, this proposal is generating great interest in the Bitcoin community and deserves continued attention.
BitVM might just be the ultimate innovation that Bitcoin needs to evolve into new possibilities for using Bitcoin.
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