btcd/btcec/schnorr/musig2/musig2_test.go

827 lines
22 KiB
Go

// Copyright 2013-2022 The btcsuite developers
package musig2
import (
"bytes"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"errors"
"flag"
"fmt"
"io/ioutil"
"sync"
"testing"
"github.com/btcsuite/btcd/btcec/v2"
"github.com/btcsuite/btcd/btcec/v2/schnorr"
)
var (
key1Bytes, _ = hex.DecodeString("F9308A019258C31049344F85F89D5229B53" +
"1C845836F99B08601F113BCE036F9")
key2Bytes, _ = hex.DecodeString("DFF1D77F2A671C5F36183726DB2341BE58F" +
"EAE1DA2DECED843240F7B502BA659")
key3Bytes, _ = hex.DecodeString("3590A94E768F8E1815C2F24B4D80A8E3149" +
"316C3518CE7B7AD338368D038CA66")
testKeys = [][]byte{key1Bytes, key2Bytes, key3Bytes}
keyCombo1, _ = hex.DecodeString("E5830140512195D74C8307E39637CBE5FB730EBEAB80EC514CF88A877CEEEE0B")
keyCombo2, _ = hex.DecodeString("D70CD69A2647F7390973DF48CBFA2CCC407B8B2D60B08C5F1641185C7998A290")
keyCombo3, _ = hex.DecodeString("81A8B093912C9E481408D09776CEFB48AEB8B65481B6BAAFB3C5810106717BEB")
keyCombo4, _ = hex.DecodeString("2EB18851887E7BDC5E830E89B19DDBC28078F1FA88AAD0AD01CA06FE4F80210B")
)
const (
keyAggTestVectorName = "key_agg_vectors.json"
signTestVectorName = "sign_vectors.json"
)
var dumpJson = flag.Bool("dumpjson", false, "if true, a JSON version of the "+
"test vectors will be written to the cwd")
type jsonKeyAggTestCase struct {
Keys []string `json:"keys"`
ExpectedKey string `json:"expected_key"`
}
// TestMuSig2KeyAggTestVectors tests that this implementation of musig2 key
// aggregation lines up with the secp256k1-zkp test vectors.
func TestMuSig2KeyAggTestVectors(t *testing.T) {
t.Parallel()
var jsonCases []jsonKeyAggTestCase
testCases := []struct {
keyOrder []int
expectedKey []byte
}{
// Keys in backwards lexicographical order.
{
keyOrder: []int{0, 1, 2},
expectedKey: keyCombo1,
},
// Keys in sorted order.
{
keyOrder: []int{2, 1, 0},
expectedKey: keyCombo2,
},
// Only the first key.
{
keyOrder: []int{0, 0, 0},
expectedKey: keyCombo3,
},
// Duplicate the first key and second keys.
{
keyOrder: []int{0, 0, 1, 1},
expectedKey: keyCombo4,
},
}
for i, testCase := range testCases {
testName := fmt.Sprintf("%v", testCase.keyOrder)
t.Run(testName, func(t *testing.T) {
var (
keys []*btcec.PublicKey
strKeys []string
)
for _, keyIndex := range testCase.keyOrder {
keyBytes := testKeys[keyIndex]
pub, err := schnorr.ParsePubKey(keyBytes)
if err != nil {
t.Fatalf("unable to parse pubkeys: %v", err)
}
keys = append(keys, pub)
strKeys = append(strKeys, hex.EncodeToString(keyBytes))
}
jsonCases = append(jsonCases, jsonKeyAggTestCase{
Keys: strKeys,
ExpectedKey: hex.EncodeToString(testCase.expectedKey),
})
uniqueKeyIndex := secondUniqueKeyIndex(keys, false)
combinedKey, _, _, _ := AggregateKeys(
keys, false, WithUniqueKeyIndex(uniqueKeyIndex),
)
combinedKeyBytes := schnorr.SerializePubKey(combinedKey.FinalKey)
if !bytes.Equal(combinedKeyBytes, testCase.expectedKey) {
t.Fatalf("case: #%v, invalid aggregation: "+
"expected %x, got %x", i, testCase.expectedKey,
combinedKeyBytes)
}
})
}
if *dumpJson {
jsonBytes, err := json.Marshal(jsonCases)
if err != nil {
t.Fatalf("unable to encode json: %v", err)
}
var formattedJson bytes.Buffer
json.Indent(&formattedJson, jsonBytes, "", "\t")
err = ioutil.WriteFile(
keyAggTestVectorName, formattedJson.Bytes(), 0644,
)
if err != nil {
t.Fatalf("unable to write file: %v", err)
}
}
}
func mustParseHex(str string) []byte {
b, err := hex.DecodeString(str)
if err != nil {
panic(fmt.Errorf("unable to parse hex: %v", err))
}
return b
}
func parseKey(xHex string) *btcec.PublicKey {
xB, err := hex.DecodeString(xHex)
if err != nil {
panic(err)
}
var x, y btcec.FieldVal
x.SetByteSlice(xB)
if !btcec.DecompressY(&x, false, &y) {
panic("x not on curve")
}
y.Normalize()
return btcec.NewPublicKey(&x, &y)
}
var (
signSetPrivKey, _ = btcec.PrivKeyFromBytes(
mustParseHex("7FB9E0E687ADA1EEBF7ECFE2F21E73EBDB51A7D450948DFE8D76D7F2D1007671"),
)
signSetPubKey, _ = schnorr.ParsePubKey(schnorr.SerializePubKey(signSetPrivKey.PubKey()))
signTestMsg = mustParseHex("F95466D086770E689964664219266FE5ED215C92AE20BAB5C9D79ADDDDF3C0CF")
signSetKey2, _ = schnorr.ParsePubKey(
mustParseHex("F9308A019258C31049344F85F89D5229B531C845836F99B086" +
"01F113BCE036F9"),
)
signSetKey3, _ = schnorr.ParsePubKey(
mustParseHex("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843" +
"240F7B502BA659"),
)
signSetKeys = []*btcec.PublicKey{signSetPubKey, signSetKey2, signSetKey3}
)
func formatTweakParity(tweaks []KeyTweakDesc) string {
var s string
for _, tweak := range tweaks {
s += fmt.Sprintf("%v/", tweak.IsXOnly)
}
// Snip off that last '/'.
s = s[:len(s)-1]
return s
}
func genTweakParity(tweak KeyTweakDesc, isXOnly bool) KeyTweakDesc {
tweak.IsXOnly = isXOnly
return tweak
}
type jsonTweak struct {
Tweak string `json:"tweak"`
XOnly bool `json:"x_only"`
}
type tweakSignCase struct {
Keys []string `json:"keys"`
Tweaks []jsonTweak `json:"tweaks,omitempty"`
ExpectedSig string `json:"expected_sig"`
}
type jsonSignTestCase struct {
SecNonce string `json:"secret_nonce"`
AggNonce string `json:"agg_nonce"`
SigningKey string `json:"signing_key"`
Msg string `json:"msg"`
TestCases []tweakSignCase `json:"test_cases"`
}
// TestMuSig2SigningTestVectors tests that the musig2 implementation produces
// the same set of signatures.
func TestMuSig2SigningTestVectors(t *testing.T) {
t.Parallel()
var jsonCases jsonSignTestCase
jsonCases.SigningKey = hex.EncodeToString(signSetPrivKey.Serialize())
jsonCases.Msg = hex.EncodeToString(signTestMsg)
var aggregatedNonce [PubNonceSize]byte
copy(
aggregatedNonce[:],
mustParseHex("028465FCF0BBDBCF443AABCCE533D42B4B5A10966AC09A49655E8C42DAAB8FCD61"),
)
copy(
aggregatedNonce[33:],
mustParseHex("037496A3CC86926D452CAFCFD55D25972CA1675D549310DE296BFF42F72EEEA8C9"),
)
jsonCases.AggNonce = hex.EncodeToString(aggregatedNonce[:])
var secNonce [SecNonceSize]byte
copy(secNonce[:], mustParseHex("508B81A611F100A6B2B6B29656590898AF488BCF2E1F55CF22E5CFB84421FE61"))
copy(secNonce[32:], mustParseHex("FA27FD49B1D50085B481285E1CA205D55C82CC1B31FF5CD54A489829355901F7"))
jsonCases.SecNonce = hex.EncodeToString(secNonce[:])
tweak1 := KeyTweakDesc{
Tweak: [32]byte{
0xE8, 0xF7, 0x91, 0xFF, 0x92, 0x25, 0xA2, 0xAF,
0x01, 0x02, 0xAF, 0xFF, 0x4A, 0x9A, 0x72, 0x3D,
0x96, 0x12, 0xA6, 0x82, 0xA2, 0x5E, 0xBE, 0x79,
0x80, 0x2B, 0x26, 0x3C, 0xDF, 0xCD, 0x83, 0xBB,
},
}
tweak2 := KeyTweakDesc{
Tweak: [32]byte{
0xae, 0x2e, 0xa7, 0x97, 0xcc, 0xf, 0xe7, 0x2a,
0xc5, 0xb9, 0x7b, 0x97, 0xf3, 0xc6, 0x95, 0x7d,
0x7e, 0x41, 0x99, 0xa1, 0x67, 0xa5, 0x8e, 0xb0,
0x8b, 0xca, 0xff, 0xda, 0x70, 0xac, 0x4, 0x55,
},
}
tweak3 := KeyTweakDesc{
Tweak: [32]byte{
0xf5, 0x2e, 0xcb, 0xc5, 0x65, 0xb3, 0xd8, 0xbe,
0xa2, 0xdf, 0xd5, 0xb7, 0x5a, 0x4f, 0x45, 0x7e,
0x54, 0x36, 0x98, 0x9, 0x32, 0x2e, 0x41, 0x20,
0x83, 0x16, 0x26, 0xf2, 0x90, 0xfa, 0x87, 0xe0,
},
}
tweak4 := KeyTweakDesc{
Tweak: [32]byte{
0x19, 0x69, 0xad, 0x73, 0xcc, 0x17, 0x7f, 0xa0,
0xb4, 0xfc, 0xed, 0x6d, 0xf1, 0xf7, 0xbf, 0x99,
0x7, 0xe6, 0x65, 0xfd, 0xe9, 0xba, 0x19, 0x6a,
0x74, 0xfe, 0xd0, 0xa3, 0xcf, 0x5a, 0xef, 0x9d,
},
}
testCases := []struct {
keyOrder []int
expectedPartialSig []byte
tweaks []KeyTweakDesc
}{
{
keyOrder: []int{0, 1, 2},
expectedPartialSig: mustParseHex("68537CC5234E505BD14061F8DA9E90C220A181855FD8BDB7F127BB12403B4D3B"),
},
{
keyOrder: []int{1, 0, 2},
expectedPartialSig: mustParseHex("2DF67BFFF18E3DE797E13C6475C963048138DAEC5CB20A357CECA7C8424295EA"),
},
{
keyOrder: []int{1, 2, 0},
expectedPartialSig: mustParseHex("0D5B651E6DE34A29A12DE7A8B4183B4AE6A7F7FBE15CDCAFA4A3D1BCAABC7517"),
},
// A single x-only tweak.
{
keyOrder: []int{1, 2, 0},
expectedPartialSig: mustParseHex("5e24c7496b565debc3b9639e6f1304a21597f9603d3ab05b4913641775e1375b"),
tweaks: []KeyTweakDesc{genTweakParity(tweak1, true)},
},
// A single ordinary tweak.
{
keyOrder: []int{1, 2, 0},
expectedPartialSig: mustParseHex("78408ddcab4813d1394c97d493ef1084195c1d4b52e63ecd7bc5991644e44ddd"),
tweaks: []KeyTweakDesc{genTweakParity(tweak1, false)},
},
// An ordinary tweak then an x-only tweak.
{
keyOrder: []int{1, 2, 0},
expectedPartialSig: mustParseHex("C3A829A81480E36EC3AB052964509A94EBF34210403D16B226A6F16EC85B7357"),
tweaks: []KeyTweakDesc{
genTweakParity(tweak1, false),
genTweakParity(tweak2, true),
},
},
// Four tweaks, in the order: x-only, ordinary, x-only, ordinary.
{
keyOrder: []int{1, 2, 0},
expectedPartialSig: mustParseHex("8C4473C6A382BD3C4AD7BE59818DA5ED7CF8CEC4BC21996CFDA08BB4316B8BC7"),
tweaks: []KeyTweakDesc{
genTweakParity(tweak1, true),
genTweakParity(tweak2, false),
genTweakParity(tweak3, true),
genTweakParity(tweak4, false),
},
},
}
var msg [32]byte
copy(msg[:], signTestMsg)
for _, testCase := range testCases {
testName := fmt.Sprintf("%v/tweak=%v", testCase.keyOrder, len(testCase.tweaks) != 0)
if len(testCase.tweaks) != 0 {
testName += fmt.Sprintf("/x_only=%v", formatTweakParity(testCase.tweaks))
}
t.Run(testName, func(t *testing.T) {
var strKeys []string
keySet := make([]*btcec.PublicKey, 0, len(testCase.keyOrder))
for _, keyIndex := range testCase.keyOrder {
keySet = append(keySet, signSetKeys[keyIndex])
strKeys = append(
strKeys, hex.EncodeToString(
schnorr.SerializePubKey(signSetKeys[keyIndex]),
),
)
}
var opts []SignOption
if len(testCase.tweaks) != 0 {
opts = append(
opts, WithTweaks(testCase.tweaks...),
)
}
var jsonTweaks []jsonTweak
for _, tweak := range testCase.tweaks {
jsonTweaks = append(jsonTweaks, jsonTweak{
Tweak: hex.EncodeToString(tweak.Tweak[:]),
XOnly: tweak.IsXOnly,
})
}
partialSig, err := Sign(
secNonce, signSetPrivKey, aggregatedNonce,
keySet, msg, opts...,
)
if err != nil {
t.Fatalf("unable to generate partial sig: %v", err)
}
var partialSigBytes [32]byte
partialSig.S.PutBytesUnchecked(partialSigBytes[:])
if !bytes.Equal(partialSigBytes[:], testCase.expectedPartialSig) {
t.Fatalf("sigs don't match: expected %x, got %x",
testCase.expectedPartialSig, partialSigBytes,
)
}
jsonCases.TestCases = append(jsonCases.TestCases, tweakSignCase{
Keys: strKeys,
Tweaks: jsonTweaks,
ExpectedSig: hex.EncodeToString(testCase.expectedPartialSig),
})
})
}
if *dumpJson {
jsonBytes, err := json.Marshal(jsonCases)
if err != nil {
t.Fatalf("unable to encode json: %v", err)
}
var formattedJson bytes.Buffer
json.Indent(&formattedJson, jsonBytes, "", "\t")
err = ioutil.WriteFile(
signTestVectorName, formattedJson.Bytes(), 0644,
)
if err != nil {
t.Fatalf("unable to write file: %v", err)
}
}
}
type signer struct {
privKey *btcec.PrivateKey
pubKey *btcec.PublicKey
nonces *Nonces
partialSig *PartialSignature
}
type signerSet []signer
func (s signerSet) keys() []*btcec.PublicKey {
keys := make([]*btcec.PublicKey, len(s))
for i := 0; i < len(s); i++ {
keys[i] = s[i].pubKey
}
return keys
}
func (s signerSet) partialSigs() []*PartialSignature {
sigs := make([]*PartialSignature, len(s))
for i := 0; i < len(s); i++ {
sigs[i] = s[i].partialSig
}
return sigs
}
func (s signerSet) pubNonces() [][PubNonceSize]byte {
nonces := make([][PubNonceSize]byte, len(s))
for i := 0; i < len(s); i++ {
nonces[i] = s[i].nonces.PubNonce
}
return nonces
}
func (s signerSet) combinedKey() *btcec.PublicKey {
uniqueKeyIndex := secondUniqueKeyIndex(s.keys(), false)
key, _, _, _ := AggregateKeys(
s.keys(), false, WithUniqueKeyIndex(uniqueKeyIndex),
)
return key.FinalKey
}
// testMultiPartySign executes a multi-party signing context w/ 100 signers.
func testMultiPartySign(t *testing.T, taprootTweak []byte,
tweaks ...KeyTweakDesc) {
const numSigners = 100
// First generate the set of signers along with their public keys.
signerKeys := make([]*btcec.PrivateKey, numSigners)
signSet := make([]*btcec.PublicKey, numSigners)
for i := 0; i < numSigners; i++ {
privKey, err := btcec.NewPrivateKey()
if err != nil {
t.Fatalf("unable to gen priv key: %v", err)
}
pubKey, err := schnorr.ParsePubKey(
schnorr.SerializePubKey(privKey.PubKey()),
)
if err != nil {
t.Fatalf("unable to gen key: %v", err)
}
signerKeys[i] = privKey
signSet[i] = pubKey
}
var combinedKey *btcec.PublicKey
var ctxOpts []ContextOption
switch {
case len(taprootTweak) == 0:
ctxOpts = append(ctxOpts, WithBip86TweakCtx())
case taprootTweak != nil:
ctxOpts = append(ctxOpts, WithTaprootTweakCtx(taprootTweak))
case len(tweaks) != 0:
ctxOpts = append(ctxOpts, WithTweakedContext(tweaks...))
}
ctxOpts = append(ctxOpts, WithKnownSigners(signSet))
// Now that we have all the signers, we'll make a new context, then
// generate a new session for each of them(which handles nonce
// generation).
signers := make([]*Session, numSigners)
for i, signerKey := range signerKeys {
signCtx, err := NewContext(
signerKey, false, ctxOpts...,
)
if err != nil {
t.Fatalf("unable to generate context: %v", err)
}
if combinedKey == nil {
combinedKey, err = signCtx.CombinedKey()
if err != nil {
t.Fatalf("combined key not available: %v", err)
}
}
session, err := signCtx.NewSession()
if err != nil {
t.Fatalf("unable to generate new session: %v", err)
}
signers[i] = session
}
// Next, in the pre-signing phase, we'll send all the nonces to each
// signer.
var wg sync.WaitGroup
for i, signCtx := range signers {
signCtx := signCtx
wg.Add(1)
go func(idx int, signer *Session) {
defer wg.Done()
for j, otherCtx := range signers {
if idx == j {
continue
}
nonce := otherCtx.PublicNonce()
haveAll, err := signer.RegisterPubNonce(nonce)
if err != nil {
t.Fatalf("unable to add public nonce")
}
if j == len(signers)-1 && !haveAll {
t.Fatalf("all public nonces should have been detected")
}
}
}(i, signCtx)
}
wg.Wait()
msg := sha256.Sum256([]byte("let's get taprooty"))
// In the final step, we'll use the first signer as our combiner, and
// generate a signature for each signer, and then accumulate that with
// the combiner.
combiner := signers[0]
for i := range signers {
signer := signers[i]
partialSig, err := signer.Sign(msg)
if err != nil {
t.Fatalf("unable to generate partial sig: %v", err)
}
// We don't need to combine the signature for the very first
// signer, as it already has that partial signature.
if i != 0 {
haveAll, err := combiner.CombineSig(partialSig)
if err != nil {
t.Fatalf("unable to combine sigs: %v", err)
}
if i == len(signers)-1 && !haveAll {
t.Fatalf("final sig wasn't reconstructed")
}
}
}
// Finally we'll combined all the nonces, and ensure that it validates
// as a single schnorr signature.
finalSig := combiner.FinalSig()
if !finalSig.Verify(msg[:], combinedKey) {
t.Fatalf("final sig is invalid!")
}
// Verify that if we try to sign again with any of the existing
// signers, then we'll get an error as the nonces have already been
// used.
for _, signer := range signers {
_, err := signer.Sign(msg)
if err != ErrSigningContextReuse {
t.Fatalf("expected to get signing context reuse")
}
}
}
// TestMuSigMultiParty tests that for a given set of 100 signers, we're able to
// properly generate valid sub signatures, which ultimately can be combined
// into a single valid signature.
func TestMuSigMultiParty(t *testing.T) {
t.Parallel()
testTweak := [32]byte{
0xE8, 0xF7, 0x91, 0xFF, 0x92, 0x25, 0xA2, 0xAF,
0x01, 0x02, 0xAF, 0xFF, 0x4A, 0x9A, 0x72, 0x3D,
0x96, 0x12, 0xA6, 0x82, 0xA2, 0x5E, 0xBE, 0x79,
0x80, 0x2B, 0x26, 0x3C, 0xDF, 0xCD, 0x83, 0xBB,
}
t.Run("no_tweak", func(t *testing.T) {
t.Parallel()
testMultiPartySign(t, nil)
})
t.Run("tweaked", func(t *testing.T) {
t.Parallel()
testMultiPartySign(t, nil, KeyTweakDesc{
Tweak: testTweak,
})
})
t.Run("tweaked_x_only", func(t *testing.T) {
t.Parallel()
testMultiPartySign(t, nil, KeyTweakDesc{
Tweak: testTweak,
IsXOnly: true,
})
})
t.Run("taproot_tweaked_x_only", func(t *testing.T) {
t.Parallel()
testMultiPartySign(t, testTweak[:])
})
t.Run("taproot_bip_86", func(t *testing.T) {
t.Parallel()
testMultiPartySign(t, []byte{})
})
}
// TestMuSigEarlyNonce tests that for protocols where nonces need to be
// exchagned before all signers are known, the context API works as expected.
func TestMuSigEarlyNonce(t *testing.T) {
t.Parallel()
privKey1, err := btcec.NewPrivateKey()
if err != nil {
t.Fatalf("unable to gen priv key: %v", err)
}
privKey2, err := btcec.NewPrivateKey()
if err != nil {
t.Fatalf("unable to gen priv key: %v", err)
}
// If we try to make a context, with just the private key and sorting
// value, we should get an error.
_, err = NewContext(privKey1, true)
if !errors.Is(err, ErrSignersNotSpecified) {
t.Fatalf("unexpected ctx error: %v", err)
}
numSigners := 2
ctx1, err := NewContext(
privKey1, true, WithNumSigners(numSigners), WithEarlyNonceGen(),
)
if err != nil {
t.Fatalf("unable to make ctx: %v", err)
}
pubKey1 := ctx1.PubKey()
ctx2, err := NewContext(
privKey2, true, WithNumSigners(numSigners), WithEarlyNonceGen(),
)
if err != nil {
t.Fatalf("unable to make ctx: %v", err)
}
pubKey2 := ctx2.PubKey()
// At this point, the combined key shouldn't be available for both
// signers, since we only know of the sole signers.
if _, err := ctx1.CombinedKey(); !errors.Is(err, ErrNotEnoughSigners) {
t.Fatalf("unepxected error: %v", err)
}
if _, err := ctx2.CombinedKey(); !errors.Is(err, ErrNotEnoughSigners) {
t.Fatalf("unepxected error: %v", err)
}
// The early nonces _should_ be available at this point.
nonce1, err := ctx1.EarlySessionNonce()
if err != nil {
t.Fatalf("session nonce not available: %v", err)
}
nonce2, err := ctx2.EarlySessionNonce()
if err != nil {
t.Fatalf("session nonce not available: %v", err)
}
// The number of registered signers should still be 1 for both parties.
if ctx1.NumRegisteredSigners() != 1 {
t.Fatalf("expected 1 signer, instead have: %v",
ctx1.NumRegisteredSigners())
}
if ctx2.NumRegisteredSigners() != 1 {
t.Fatalf("expected 1 signer, instead have: %v",
ctx2.NumRegisteredSigners())
}
// If we try to make a session, we should get an error since we dn't
// have all the signers yet.
if _, err := ctx1.NewSession(); !errors.Is(err, ErrNotEnoughSigners) {
t.Fatalf("unexpected session key error: %v", err)
}
// The combined key should also be unavailable as well.
if _, err := ctx1.CombinedKey(); !errors.Is(err, ErrNotEnoughSigners) {
t.Fatalf("unexpected combined key error: %v", err)
}
// We'll now register the other signer for both parties.
done, err := ctx1.RegisterSigner(&pubKey2)
if err != nil {
t.Fatalf("unable to register signer: %v", err)
}
if !done {
t.Fatalf("signer 1 doesn't have all keys")
}
done, err = ctx2.RegisterSigner(&pubKey1)
if err != nil {
t.Fatalf("unable to register signer: %v", err)
}
if !done {
t.Fatalf("signer 2 doesn't have all keys")
}
// If we try to register the signer again, we should get an error.
_, err = ctx2.RegisterSigner(&pubKey1)
if !errors.Is(err, ErrAlreadyHaveAllSigners) {
t.Fatalf("should not be able to register too many signers")
}
// We should be able to create the session at this point.
session1, err := ctx1.NewSession()
if err != nil {
t.Fatalf("unable to create new session: %v", err)
}
session2, err := ctx2.NewSession()
if err != nil {
t.Fatalf("unable to create new session: %v", err)
}
msg := sha256.Sum256([]byte("let's get taprooty, LN style"))
// If we try to sign before we have the combined nonce, we shoudl get
// an error.
_, err = session1.Sign(msg)
if !errors.Is(err, ErrCombinedNonceUnavailable) {
t.Fatalf("unable to gen sig: %v", err)
}
// Now we can exchange nonces to continue with the rest of the signing
// process as normal.
done, err = session1.RegisterPubNonce(nonce2.PubNonce)
if err != nil {
t.Fatalf("unable to register nonce: %v", err)
}
if !done {
t.Fatalf("signer 1 doesn't have all nonces")
}
done, err = session2.RegisterPubNonce(nonce1.PubNonce)
if err != nil {
t.Fatalf("unable to register nonce: %v", err)
}
if !done {
t.Fatalf("signer 2 doesn't have all nonces")
}
// Registering the nonce again should error out.
_, err = session2.RegisterPubNonce(nonce1.PubNonce)
if !errors.Is(err, ErrAlredyHaveAllNonces) {
t.Fatalf("shouldn't be able to register nonces twice")
}
// Sign the message and combine the two partial sigs into one.
_, err = session1.Sign(msg)
if err != nil {
t.Fatalf("unable to gen sig: %v", err)
}
sig2, err := session2.Sign(msg)
if err != nil {
t.Fatalf("unable to gen sig: %v", err)
}
done, err = session1.CombineSig(sig2)
if err != nil {
t.Fatalf("unable to combine sig: %v", err)
}
if !done {
t.Fatalf("all sigs should be known now: %v", err)
}
// If we try to combine another sig, then we should get an error.
_, err = session1.CombineSig(sig2)
if !errors.Is(err, ErrAlredyHaveAllSigs) {
t.Fatalf("shouldn't be able to combine again")
}
// Finally, verify that the final signature is valid.
combinedKey, err := ctx1.CombinedKey()
if err != nil {
t.Fatalf("unexpected combined key error: %v", err)
}
finalSig := session1.FinalSig()
if !finalSig.Verify(msg[:], combinedKey) {
t.Fatalf("final sig is invalid!")
}
}