signer: add MuSig2 combined nonce registration methods

go.mod

@@ -2,14 +2,14 @@ module github.com/lightninglabs/lndclient
 
 require (
 	github.com/btcsuite/btcd v0.24.3-0.20250318170759-4f4ea81776d6
-	github.com/btcsuite/btcd/btcec/v2 v2.3.4
+	github.com/btcsuite/btcd/btcec/v2 v2.3.6
 	github.com/btcsuite/btcd/btcutil v1.1.5
 	github.com/btcsuite/btcd/btcutil/psbt v1.1.8
 	github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0
 	github.com/btcsuite/btclog/v2 v2.0.1-0.20250728225537-6090e87c6c5b
 	github.com/btcsuite/btcwallet v0.16.17
 	github.com/btcsuite/btcwallet/wtxmgr v1.5.6
-	github.com/lightningnetwork/lnd v0.20.0-beta
+	github.com/lightningnetwork/lnd v0.20.0-beta.rc4.0.20260110233730-15227a4ff50a
 	github.com/lightningnetwork/lnd/kvdb v1.4.16
 	github.com/stretchr/testify v1.10.0
 	google.golang.org/grpc v1.59.0
@@ -103,7 +103,7 @@ require (
 	github.com/lightningnetwork/lnd/fn/v2 v2.0.9 // indirect
 	github.com/lightningnetwork/lnd/healthcheck v1.2.6 // indirect
 	github.com/lightningnetwork/lnd/queue v1.1.1 // indirect
-	github.com/lightningnetwork/lnd/sqldb v1.0.11 // indirect
+	github.com/lightningnetwork/lnd/sqldb v1.0.12 // indirect
 	github.com/lightningnetwork/lnd/ticker v1.1.1 // indirect
 	github.com/lightningnetwork/lnd/tlv v1.3.2 // indirect
 	github.com/lightningnetwork/lnd/tor v1.1.6 // indirect

go.sum

@@ -39,8 +39,8 @@ github.com/btcsuite/btcd v0.24.3-0.20250318170759-4f4ea81776d6 h1:8n9k3I7e8DkpdQ
 github.com/btcsuite/btcd v0.24.3-0.20250318170759-4f4ea81776d6/go.mod h1:OmM4kFtB0klaG/ZqT86rQiyw/1iyXlJgc3UHClPhhbs=
 github.com/btcsuite/btcd/btcec/v2 v2.1.0/go.mod h1:2VzYrv4Gm4apmbVVsSq5bqf1Ec8v56E48Vt0Y/umPgA=
 github.com/btcsuite/btcd/btcec/v2 v2.1.3/go.mod h1:ctjw4H1kknNJmRN4iP1R7bTQ+v3GJkZBd6mui8ZsAZE=
-github.com/btcsuite/btcd/btcec/v2 v2.3.4 h1:3EJjcN70HCu/mwqlUsGK8GcNVyLVxFDlWurTXGPFfiQ=
-github.com/btcsuite/btcd/btcec/v2 v2.3.4/go.mod h1:zYzJ8etWJQIv1Ogk7OzpWjowwOdXY1W/17j2MW85J04=
+github.com/btcsuite/btcd/btcec/v2 v2.3.6 h1:IzlsEr9olcSRKB/n7c4351F3xHKxS2lma+1UFGCYd4E=
+github.com/btcsuite/btcd/btcec/v2 v2.3.6/go.mod h1:m22FrOAiuxl/tht9wIqAoGHcbnCCaPWyauO8y2LGGtQ=
 github.com/btcsuite/btcd/btcutil v1.0.0/go.mod h1:Uoxwv0pqYWhD//tfTiipkxNfdhG9UrLwaeswfjfdF0A=
 github.com/btcsuite/btcd/btcutil v1.1.0/go.mod h1:5OapHB7A2hBBWLm48mmw4MOHNJCcUBTwmWH/0Jn8VHE=
 github.com/btcsuite/btcd/btcutil v1.1.5 h1:+wER79R5670vs/ZusMTF1yTcRYE5GUsFbdjdisflzM8=
@@ -356,8 +356,8 @@ github.com/lightninglabs/protobuf-go-hex-display v1.33.0-hex-display h1:Y2WiPkBS
 github.com/lightninglabs/protobuf-go-hex-display v1.33.0-hex-display/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
 github.com/lightningnetwork/lightning-onion v1.2.1-0.20240815225420-8b40adf04ab9 h1:6D3LrdagJweLLdFm1JNodZsBk6iU4TTsBBFLQ4yiXfI=
 github.com/lightningnetwork/lightning-onion v1.2.1-0.20240815225420-8b40adf04ab9/go.mod h1:EDqJ3MuZIbMq0QI1czTIKDJ/GS8S14RXPwapHw8cw6w=
-github.com/lightningnetwork/lnd v0.20.0-beta h1:ML+jgJ3UKDGJdUf0m73ZeR/szJKWVtHxpQP+yFC79b8=
-github.com/lightningnetwork/lnd v0.20.0-beta/go.mod h1:8hc55AnE3mMSJ/UAEJZgmhgNCcH0yWaPg0olpxhhp4M=
+github.com/lightningnetwork/lnd v0.20.0-beta.rc4.0.20260110233730-15227a4ff50a h1:iRR8gWsS7rPTz7GRmyBu/QU0kXBAPi/FYxfnrhuh9Y4=
+github.com/lightningnetwork/lnd v0.20.0-beta.rc4.0.20260110233730-15227a4ff50a/go.mod h1:OycW7yPCaApWsIqLthe8QHxk4dM5wOw0LPcUXjr3a5s=
 github.com/lightningnetwork/lnd/clock v1.1.1 h1:OfR3/zcJd2RhH0RU+zX/77c0ZiOnIMsDIBjgjWdZgA0=
 github.com/lightningnetwork/lnd/clock v1.1.1/go.mod h1:mGnAhPyjYZQJmebS7aevElXKTFDuO+uNFFfMXK1W8xQ=
 github.com/lightningnetwork/lnd/fn/v2 v2.0.9 h1:ZytG4ltPac/sCyg1EJDn10RGzPIDJeyennUMRdOw7Y8=
@@ -368,8 +368,8 @@ github.com/lightningnetwork/lnd/kvdb v1.4.16 h1:9BZgWdDfjmHRHLS97cz39bVuBAqMc4/p
 github.com/lightningnetwork/lnd/kvdb v1.4.16/go.mod h1:HW+bvwkxNaopkz3oIgBV6NEnV4jCEZCACFUcNg4xSjM=
 github.com/lightningnetwork/lnd/queue v1.1.1 h1:99ovBlpM9B0FRCGYJo6RSFDlt8/vOkQQZznVb18iNMI=
 github.com/lightningnetwork/lnd/queue v1.1.1/go.mod h1:7A6nC1Qrm32FHuhx/mi1cieAiBZo5O6l8IBIoQxvkz4=
-github.com/lightningnetwork/lnd/sqldb v1.0.11 h1:X8J3OvdIhJVniQG78Qsp3niErl1zdGMTPvzgiLMWOOo=
-github.com/lightningnetwork/lnd/sqldb v1.0.11/go.mod h1:oOdZ7vjmAUmI9He+aFHTunnxKVefHZAfJttZdz16hSg=
+github.com/lightningnetwork/lnd/sqldb v1.0.12 h1:cNJsL+ymCtTn9DqroszZixKaD96GN32ujpHUYvrkN30=
+github.com/lightningnetwork/lnd/sqldb v1.0.12/go.mod h1:Ic65SUa2pJzc3sWSZqDTrWo5qdKIS1zu/blhSddF7X8=
 github.com/lightningnetwork/lnd/ticker v1.1.1 h1:J/b6N2hibFtC7JLV77ULQp++QLtCwT6ijJlbdiZFbSM=
 github.com/lightningnetwork/lnd/ticker v1.1.1/go.mod h1:waPTRAAcwtu7Ji3+3k+u/xH5GHovTsCoSVpho0KDvdA=
 github.com/lightningnetwork/lnd/tlv v1.3.2 h1:MO4FCk7F4k5xPMqVZF6Nb/kOpxlwPrUQpYjmyKny5s0=

signer_client.go

@@ -101,6 +101,25 @@ type SignerClient interface {
 
 	// MuSig2Cleanup removes a session from memory to free up resources.
 	MuSig2Cleanup(ctx context.Context, sessionID [32]byte) error
+
+	// MuSig2RegisterCombinedNonce registers a pre-aggregated combined nonce
+	// for a session identified by its ID. This is an alternative to
+	// MuSig2RegisterNonces and is used when a coordinator has already
+	// aggregated all individual nonces and wants to distribute the combined
+	// nonce to participants.
+	//
+	// NOTE: This method is mutually exclusive with MuSig2RegisterNonces for
+	// the same session. Once this method is called, MuSig2RegisterNonces
+	// will return an error if called later for the same session.
+	MuSig2RegisterCombinedNonce(ctx context.Context, sessionID [32]byte,
+		combinedNonce [66]byte) error
+
+	// MuSig2GetCombinedNonce retrieves the combined nonce for a session
+	// identified by its ID. This will be available after either all
+	// individual nonces have been registered via MuSig2RegisterNonces, or a
+	// combined nonce has been registered via MuSig2RegisterCombinedNonce.
+	MuSig2GetCombinedNonce(ctx context.Context,
+		sessionID [32]byte) ([66]byte, error)
 }
 
 // SignDescriptor houses the necessary information required to successfully
@@ -765,3 +784,55 @@ func (s *signerClient) MuSig2Cleanup(ctx context.Context,
 
 	return err
 }
+
+// MuSig2RegisterCombinedNonce registers a pre-aggregated combined nonce for a
+// session identified by its ID. This is an alternative to MuSig2RegisterNonces
+// and is used when a coordinator has already aggregated all individual nonces
+// and wants to distribute the combined nonce to participants.
+func (s *signerClient) MuSig2RegisterCombinedNonce(ctx context.Context,
+	sessionID [32]byte, combinedNonce [66]byte) error {
+
+	req := &signrpc.MuSig2RegisterCombinedNonceRequest{
+		SessionId:           sessionID[:],
+		CombinedPublicNonce: combinedNonce[:],
+	}
+
+	rpcCtx, cancel := context.WithTimeout(ctx, s.timeout)
+	defer cancel()
+
+	rpcCtx = s.signerMac.WithMacaroonAuth(rpcCtx)
+	_, err := s.client.MuSig2RegisterCombinedNonce(rpcCtx, req)
+
+	return err
+}
+
+// MuSig2GetCombinedNonce retrieves the combined nonce for a session identified
+// by its ID. This will be available after either all individual nonces have
+// been registered via MuSig2RegisterNonces, or a combined nonce has been
+// registered via MuSig2RegisterCombinedNonce.
+func (s *signerClient) MuSig2GetCombinedNonce(ctx context.Context,
+	sessionID [32]byte) ([66]byte, error) {
+
+	req := &signrpc.MuSig2GetCombinedNonceRequest{
+		SessionId: sessionID[:],
+	}
+
+	rpcCtx, cancel := context.WithTimeout(ctx, s.timeout)
+	defer cancel()
+
+	rpcCtx = s.signerMac.WithMacaroonAuth(rpcCtx)
+	resp, err := s.client.MuSig2GetCombinedNonce(rpcCtx, req)
+	if err != nil {
+		return [66]byte{}, err
+	}
+
+	if len(resp.CombinedPublicNonce) != 66 {
+		return [66]byte{}, fmt.Errorf("unexpected combined nonce "+
+			"size: %v", len(resp.CombinedPublicNonce))
+	}
+
+	var combinedNonce [66]byte
+	copy(combinedNonce[:], resp.CombinedPublicNonce)
+
+	return combinedNonce, nil
+}

testdata/permissions.json

@@ -984,6 +984,22 @@
                 }
             ]
         },
+        "/signrpc.Signer/MuSig2RegisterCombinedNonce": {
+            "permissions": [
+                {
+                    "entity": "signer",
+                    "action": "generate"
+                }
+            ]
+        },
+        "/signrpc.Signer/MuSig2GetCombinedNonce": {
+            "permissions": [
+                {
+                    "entity": "signer",
+                    "action": "generate"
+                }
+            ]
+        },
         "/signrpc.Signer/SignMessage": {
             "permissions": [
                 {