musig2 works now.

go.mod

@@ -5,7 +5,7 @@ go 1.21
 toolchain go1.21.0
 
 require (
-	github.com/btcsuite/btcd/btcec/v2 v2.3.2
+	github.com/btcsuite/btcd/btcec/v2 v2.3.3
 	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
 	github.com/fatih/color v1.16.0
 	github.com/mailru/easyjson v0.7.7
@@ -22,7 +22,7 @@ require (
 	github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
 	github.com/decred/dcrd/crypto/blake256 v1.0.1 // indirect
-	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.2.0 // indirect
+	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0 // indirect
 	github.com/fiatjaf/eventstore v0.2.16 // indirect
 	github.com/gobwas/httphead v0.1.0 // indirect
 	github.com/gobwas/pool v0.2.1 // indirect

go.sum

@@ -6,6 +6,8 @@ github.com/btcsuite/btcd/btcec/v2 v2.1.0/go.mod h1:2VzYrv4Gm4apmbVVsSq5bqf1Ec8v5
 github.com/btcsuite/btcd/btcec/v2 v2.1.3/go.mod h1:ctjw4H1kknNJmRN4iP1R7bTQ+v3GJkZBd6mui8ZsAZE=
 github.com/btcsuite/btcd/btcec/v2 v2.3.2 h1:5n0X6hX0Zk+6omWcihdYvdAlGf2DfasC0GMf7DClJ3U=
 github.com/btcsuite/btcd/btcec/v2 v2.3.2/go.mod h1:zYzJ8etWJQIv1Ogk7OzpWjowwOdXY1W/17j2MW85J04=
+github.com/btcsuite/btcd/btcec/v2 v2.3.3 h1:6+iXlDKE8RMtKsvK0gshlXIuPbyWM/h84Ensb7o3sC0=
+github.com/btcsuite/btcd/btcec/v2 v2.3.3/go.mod h1:zYzJ8etWJQIv1Ogk7OzpWjowwOdXY1W/17j2MW85J04=
 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 v1.1.3 h1:xfbtw8lwpp0G6NwSHb+UE67ryTFHJAiNuipusjXSohQ=
@@ -41,6 +43,8 @@ github.com/decred/dcrd/crypto/blake256 v1.0.1/go.mod h1:2OfgNZ5wDpcsFmHmCK5gZTPc
 github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1/go.mod h1:hyedUtir6IdtD/7lIxGeCxkaw7y45JueMRL4DIyJDKs=
 github.com/decred/dcrd/dcrec/secp256k1/v4 v4.2.0 h1:8UrgZ3GkP4i/CLijOJx79Yu+etlyjdBU4sfcs2WYQMs=
 github.com/decred/dcrd/dcrec/secp256k1/v4 v4.2.0/go.mod h1:v57UDF4pDQJcEfFUCRop3lJL149eHGSe9Jvczhzjo/0=
+github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0 h1:rpfIENRNNilwHwZeG5+P150SMrnNEcHYvcCuK6dPZSg=
+github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0/go.mod h1:v57UDF4pDQJcEfFUCRop3lJL149eHGSe9Jvczhzjo/0=
 github.com/decred/dcrd/lru v1.0.0/go.mod h1:mxKOwFd7lFjN2GZYsiz/ecgqR6kkYAl+0pz0tEMk218=
 github.com/fatih/color v1.16.0 h1:zmkK9Ngbjj+K0yRhTVONQh1p/HknKYSlNT+vZCzyokM=
 github.com/fatih/color v1.16.0/go.mod h1:fL2Sau1YI5c0pdGEVCbKQbLXB6edEj1ZgiY4NijnWvE=

key.go

@@ -152,7 +152,7 @@ var combine = &cli.Command{
 			return err
 		}
 
-		fmt.Println(hex.EncodeToString(agg.FinalKey.X().Bytes()))
+		fmt.Println(hex.EncodeToString(agg.FinalKey.SerializeCompressed()))
 		return nil
 	},
 }

musig2.go

@@ -134,6 +134,7 @@ func performMusig(
 		if err != nil {
 			return false, fmt.Errorf("failed to create session as the last peer to include our key: %w", err)
 		}
+		knownNonces = append(knownNonces, session.PublicNonce())
 	} else {
 		// otherwise we have included our own nonce in the parameters (from copypasting) but must
 		// also include the secret nonce that wasn't shared with peers
@@ -157,13 +158,18 @@ func performMusig(
 
 	var noncesOk bool
 	for _, b66nonce := range knownNonces {
+		if b66nonce == session.PublicNonce() {
+			// don't add our own nonce
+			continue
+		}
+
 		noncesOk, err = session.RegisterPubNonce(b66nonce)
 		if err != nil {
 			return false, fmt.Errorf("failed to register nonce: %w", err)
 		}
 	}
 	if !noncesOk {
-		return false, fmt.Errorf("we've registered all the nonces we had but at least one is missing")
+		return false, fmt.Errorf("we've registered all the nonces we had but at least one is missing, this shouldn't happen")
 	}
 
 	// signing phase
@@ -172,7 +178,6 @@ func performMusig(
 	hash, _ := hex.DecodeString(id)
 	var msg32 [32]byte
 	copy(msg32[:], hash)
-	fmt.Println("signing over", hex.EncodeToString(msg32[:]))
 	partialSig, err := session.Sign(msg32) // this will already include our sig in the bundle
 	if err != nil {
 		return false, fmt.Errorf("failed to produce partial signature: %w", err)
@@ -212,7 +217,7 @@ func printPublicCommandForNextPeer(
 		maybeNonceSecret = " --musig2-nonce-secret '<their-nonce-secret>'"
 	}
 
-	fmt.Fprintf(os.Stderr, "the next signer and they should call this on their side:\nnak event --sec <their-key> --musig2 %d %s%s%s%s%s",
+	fmt.Fprintf(os.Stderr, "the next signer and they should call this on their side:\nnak event --sec <their-key> --musig2 %d %s%s%s%s%s\n",
 		numSigners,
 		eventToCliArgs(evt),
 		signersToCliArgs(knownSigners),