MuSig2GetCombinedNonce

MuSig2GetCombinedNonce (experimental!) retrieves the combined nonce for a signing session. This will be available after either all individual nonces have been registered via MuSig2RegisterNonces, or a combined nonce has been registered via MuSig2RegisterCombinedNonce.

NOTE: The MuSig2 BIP is not final yet and therefore this API must be considered to be HIGHLY EXPERIMENTAL and subject to change in upcoming releases. Backward compatibility is not guaranteed!

Source: signrpc/signer.proto

gRPC

rpc MuSig2GetCombinedNonce (MuSig2GetCombinedNonceRequest) returns (MuSig2GetCombinedNonceResponse);

REST

HTTP Method	Path
POST	/v2/signer/musig2/getcombinednonce

Code Samples

gRPC

Javascript

const fs = require('fs');
const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const GRPC_HOST = 'localhost:10009'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
const TLS_PATH = 'LND_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync(['lightning.proto', 'signrpc/signer.proto'], loaderOptions);
const signrpc = grpc.loadPackageDefinition(packageDefinition).signrpc;
process.env.GRPC_SSL_CIPHER_SUITES = 'HIGH+ECDSA';
const tlsCert = fs.readFileSync(TLS_PATH);
const sslCreds = grpc.credentials.createSsl(tlsCert);
const macaroon = fs.readFileSync(MACAROON_PATH).toString('hex');
const macaroonCreds = grpc.credentials.createFromMetadataGenerator(function(args, callback) {
  let metadata = new grpc.Metadata();
  metadata.add('macaroon', macaroon);
  callback(null, metadata);
});
let creds = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds);
let client = new signrpc.Signer(GRPC_HOST, creds);
let request = {
  session_id: <bytes>,
};
client.muSig2GetCombinedNonce(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "combined_public_nonce": <bytes>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the signrpc/signer.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import signer_pb2 as signrpc, signer_pb2_grpc as signerstub

GRPC_HOST = 'localhost:10009'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_DIR/tls.cert'

# create macaroon credentials
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
def metadata_callback(context, callback):
  callback([('macaroon', macaroon)], None)
auth_creds = grpc.metadata_call_credentials(metadata_callback)
# create SSL credentials
os.environ['GRPC_SSL_CIPHER_SUITES'] = 'HIGH+ECDSA'
cert = open(TLS_PATH, 'rb').read()
ssl_creds = grpc.ssl_channel_credentials(cert)
# combine macaroon and SSL credentials
combined_creds = grpc.composite_channel_credentials(ssl_creds, auth_creds)
# make the request
channel = grpc.secure_channel(GRPC_HOST, combined_creds)
stub = signerstub.SignerStub(channel)
request = signrpc.MuSig2GetCombinedNonceRequest(
  session_id=<bytes>,
)
response = stub.MuSig2GetCombinedNonce(request)
print(response)
# {
#    "combined_public_nonce": <bytes>,
# }

REST

Javascript

const fs = require('fs');
const request = require('request');

const REST_HOST = 'localhost:8080'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'

let requestBody = {
  session_id: <string>, // <bytes> (base64 encoded)
};
let options = {
  url: `https://${REST_HOST}/v2/signer/musig2/getcombinednonce`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
  form: JSON.stringify(requestBody),
}
request.post(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "combined_public_nonce": <string>, // <bytes> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8080'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_DIR/tls.cert'

url = f'https://{REST_HOST}/v2/signer/musig2/getcombinednonce'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
data = {
  'session_id': base64.b64encode(<bytes>),
}
r = requests.post(url, headers=headers, data=json.dumps(data), verify=TLS_PATH)
print(r.json())
# {
#    "combined_public_nonce": <bytes>,
# }

Shell

# There is no CLI command for this RPC

Messages

signrpc.MuSig2GetCombinedNonceRequest

Source: signrpc/signer.proto

Field	gRPC Type	REST Type	REST Placement
session_id The unique ID of the signing session to get the combined nonce for.	bytes	string	body

signrpc.MuSig2GetCombinedNonceResponse

Source: signrpc/signer.proto

Field	gRPC Type	REST Type
combined_public_nonce The 66-byte combined public nonce. This is a concatenation of two 33-byte compressed public keys (R1 || R2).	bytes	string