Date: Tue, 10 Oct 2023 01:12:28 +0000
To: Robin Linus <robin@zerosync.org>
From: symphonicbtc <symphonicbtc@proton.me>
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Cc: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] BitVM: Compute Anything on Bitcoin
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Hello Robin,

I'm very interested in this development, as I've been longing for arbitrary=
 smart contracts on bitcoin for a while. I've got a couple questions I'd li=
ke to ask, on behalf of myself and some others I've been discussing this wi=
th.

1. Do you have plans to implement a high-level language that can compile do=
wn to this or maybe adapt some existing VM to make these scripts? I'm sure =
many would love to get their hands on something a bit more workable to test=
 this out.

2. What are the expected computational costs of establishing the tapleaves =
for these scripts? Is it feasible to do complex things like ECDSA signature=
 checking, etc? I worry that the hardware required to use this tech will be=
 a barrier in it's widespread use.

3. Would it be possible to implement existing zero-knowledge proof construc=
ts on BitVM, and would that make verification simpler? I.e. instead of veri=
fying your program directly with BitVM, have your program be written in som=
e ZKP VM, and just have the proof verification execute on BitVM

4. What are the expected costs of resolving a fraud for a program? I assume=
 this is quite nuanced and has to do with the exact circumstances of the pr=
ogram, but would it be possible for you to provide some examples of how thi=
s might go down for some simple programs to aid comprehension?

Thanks,
Symphonic

Sent with Proton Mail secure email.

------- Original Message -------
On Monday, October 9th, 2023 at 1:46 PM, Robin Linus via bitcoin-dev <bitco=
in-dev@lists.linuxfoundation.org> wrote:


> Abstract. BitVM is a computing paradigm to express Turing-complete Bitcoi=
n contracts. This requires no changes to the network=E2=80=99s consensus ru=
les. Rather than executing computations on Bitcoin, they are merely verifie=
d, similarly to optimistic rollups. A prover makes a claim that a given fun=
ction evaluates for some particular inputs to some specific output. If that=
 claim is false, then the verifier can perform a succinct fraud proof and p=
unish the prover. Using this mechanism, any computable function can be veri=
fied on Bitcoin. Committing to a large program in a Taproot address require=
s significant amounts of off-chain computation and communication, however t=
he resulting on-chain footprint is minimal. As long as both parties collabo=
rate, they can perform arbitrarily complex, stateful off-chain computation,=
 without leaving any trace in the chain. On-chain execution is required onl=
y in case of a dispute.
>=20
> https://bitvm.org/bitvm.pdf
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> bitcoin-dev mailing list
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