multi: add ability to specify local nonces for musig2 signer rpc, add itest for remote signer taproot chans #7994
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Can you please expound on this a bit more? Not clear what RPC interface you're referring to. |
This is needed to be able to open taproot channels with a remote signer configuration. |
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| var r1, r2 btcec.JacobianPoint | ||
| btcec.ScalarBaseMultNonConst(&k1Mod, &r1) | ||
| btcec.ScalarBaseMultNonConst(&k2Mod, &r2) | ||
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| // Next, we'll convert the key in jacobian format to a normal public | ||
| // key expressed in affine coordinates. | ||
| r1.ToAffine() | ||
| r2.ToAffine() | ||
| r1Pub := btcec.NewPublicKey(&r1.X, &r1.Y) | ||
| r2Pub := btcec.NewPublicKey(&r2.X, &r2.Y) |
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Nit: I'm somewhat surprised that the singular version of this isn't its own function.
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Just mapping a secret nonce to a public nonce? It's in the musig2 package, but unadvertised. Reason is that it tries to force a "safe" API by always getting in strong randomness, then applying all the musig2-bip specific item like: appending the public key to the secret nonces itself.
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Could've exported it, but then would've had to commit to that addition to the API.
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Yeah I guess what I see here is a function that takes a full secnonce encoding, breaks it into two secret u256's and converts them to ECPoints and then reassembling them into a pubnonce encoding. Intuitively I'd expect the u256 -> ECPoint conversion to be an already existing function that got reused here. It's not a huge deal since it's probs a 3 line fn and this method is still small enough to reason about.
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…nonces In this commit, we modify the musig2 interfaces to instead use an explicit value for the local nonces. Before this commit, we used the functional option, but we want to also support specifying this value over RPC for the remote signer. The functional option pattern is opaque, so we can't get the nonce value we need. To get around this, we'll just make this an explicit pointer, then map this to the functional option at the very last moment.
In this commit, we update the set of protos to accept the local secret nonces over RPC. This is actually a 97 byte value, as it includes the two 32 byte nonces, as well as the 33 byte value of the public key of the signer. This is needed in order to be able to open taproot channels over the RPC interface.
This ensures that taproot chans can be used with the remote signer configuration.
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In this PR, we update the set of protos to accept the local secret
nonces over RPC. This is actually a 97 byte value, as it includes the
two 32 byte nonces, as well as the 33 byte value of the public key of
the signer.
This is needed in order to be able to open taproot channels over the RPC
interface.
Along the way, we modify the musig2 interfaces to instead use an
explicit value for the local nonces. Before this commit, we used the
functional option, but we want to also support specifying this value
over RPC for the remote signer. The functional option pattern is opaque,
so we can't get the nonce value we need. To get around this, we'll just
make this an explicit pointer, then map this to the functional option at
the very last moment.
Finally, we add a test case to ensure that taproot chans work w/ the
remote signer.