BTC Taproot (BIP340) compatible

[lucky1024]

Hi experts,

Are there any plans to make it BTC Taproot (BIP340) compatible?

[conradoplg]

Not currently, but it shouldn't be too hard. If anyone is wants to give it a shot, I sketched the changes needed here cfrg/draft-irtf-cfrg-frost@master...conradoplg:draft-irtf-cfrg-frost:taproot (but that's completely untested).

I'll leave this open to track it.

[lucky1024]

Not currently, but it shouldn't be too hard. If anyone is wants to give it a shot, I sketched the changes needed here cfrg/[email protected]:draft-irtf-cfrg-frost:taproot (but that's completely untested).

I'll leave this open to track it.

It seems sk_i also need be negated if group_public_key y coordinate is odd.

Here is an implentation https://github.com/jesseposner/FROST-BIP340/blob/main/frost.py

[zebra-lucky]

I've added some testing implementation.

zebra-lucky@cb22cf5

Possibly after review it can be added in some way to the upstream code.

[conradoplg]

I've added some testing implementation.

zebra-lucky@cb22cf5

Possibly after review it can be added in some way to the upstream code.

Cool! I haven't reviewed it carefully but it seems about right.

If you decide to submit a PR, note that we would prefer to create a separate ciphersuite for it, and not changing the existing secp256k1 one. (this entails basically having a separate folder for it, e.g, frost-taproot or frost-bip340 and changing the Ciphersuite name/ID accordingly).

Alternatively you can keep it as separate crate, and just submit a PR for frost-core.

[zebra-lucky]

Ок, I'll look to create a separate crate/ciphersuite.

[zebra-lucky]

I've try add a PR #584

Some more changes are probably needed.