multi: use btcd's btcec/v2 and btcutil modules

This commit was previously split into the following parts to ease
review:
 - 2d746f68: replace imports
 - 4008f0fd: use ecdsa.Signature
 - 849e33d1: remove btcec.S256()
 - b8f6ebbd: use v2 library correctly
 - fa80bca9: bump go modules

lnwire/accept_channel.go

@@ -4,8 +4,8 @@ import (
 	"bytes"
 	"io"
 
-	"github.com/btcsuite/btcd/btcec"
-	"github.com/btcsuite/btcutil"
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcutil"
 	"github.com/lightningnetwork/lnd/tlv"
 )
 

lnwire/accept_channel_test.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"testing"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
 )
 
 // TestDecodeAcceptChannel tests decoding of an accept channel wire message with
@@ -32,7 +32,7 @@ func TestDecodeAcceptChannel(t *testing.T) {
 		test := test
 
 		t.Run(test.name, func(t *testing.T) {
-			priv, err := btcec.NewPrivateKey(btcec.S256())
+			priv, err := btcec.NewPrivateKey()
 			if err != nil {
 				t.Fatalf("cannot create privkey: %v", err)
 			}

lnwire/channel_reestablish.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"io"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
 )
 
 // ChannelReestablish is a message sent between peers that have an existing

lnwire/closing_signed.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"io"
 
-	"github.com/btcsuite/btcutil"
+	"github.com/btcsuite/btcd/btcutil"
 )
 
 // ClosingSigned is sent by both parties to a channel once the channel is clear

lnwire/funding_locked.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"io"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
 )
 
 // FundingLocked is the message that both parties to a new channel creation

lnwire/lnwire.go

@@ -9,10 +9,10 @@ import (
 	"math"
 	"net"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/btcsuite/btcutil"
 	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/tor"
 )
@@ -541,7 +541,7 @@ func ReadElement(r io.Reader, element interface{}) error {
 			return err
 		}
 
-		pubKey, err := btcec.ParsePubKey(b[:], btcec.S256())
+		pubKey, err := btcec.ParsePubKey(b[:])
 		if err != nil {
 			return err
 		}

lnwire/lnwire_test.go

@@ -6,7 +6,6 @@ import (
 	"encoding/hex"
 	"image/color"
 	"math"
-	"math/big"
 	"math/rand"
 	"net"
 	"reflect"
@@ -14,10 +13,11 @@ import (
 	"testing/quick"
 	"time"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
+	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/tor"
 	"github.com/stretchr/testify/assert"
 )
@@ -26,12 +26,14 @@ var (
 	shaHash1Bytes, _ = hex.DecodeString("e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855")
 	shaHash1, _      = chainhash.NewHash(shaHash1Bytes)
 	outpoint1        = wire.NewOutPoint(shaHash1, 0)
-	testSig          = &btcec.Signature{
-		R: new(big.Int),
-		S: new(big.Int),
-	}
-	_, _ = testSig.R.SetString("63724406601629180062774974542967536251589935445068131219452686511677818569431", 10)
-	_, _ = testSig.S.SetString("18801056069249825825291287104931333862866033135609736119018462340006816851118", 10)
+
+	testRBytes, _ = hex.DecodeString("8ce2bc69281ce27da07e6683571319d18e949ddfa2965fb6caa1bf0314f882d7")
+	testSBytes, _ = hex.DecodeString("299105481d63e0f4bc2a88121167221b6700d72a0ead154c03be696a292d24ae")
+	testRScalar   = new(btcec.ModNScalar)
+	testSScalar   = new(btcec.ModNScalar)
+	_             = testRScalar.SetByteSlice(testRBytes)
+	_             = testSScalar.SetByteSlice(testSBytes)
+	testSig       = ecdsa.NewSignature(testRScalar, testSScalar)
 )
 
 const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
@@ -46,7 +48,7 @@ func randAlias(r *rand.Rand) NodeAlias {
 }
 
 func randPubKey() (*btcec.PublicKey, error) {
-	priv, err := btcec.NewPrivateKey(btcec.S256())
+	priv, err := btcec.NewPrivateKey()
 	if err != nil {
 		return nil, err
 	}
@@ -57,7 +59,7 @@ func randPubKey() (*btcec.PublicKey, error) {
 func randRawKey() ([33]byte, error) {
 	var n [33]byte
 
-	priv, err := btcec.NewPrivateKey(btcec.S256())
+	priv, err := btcec.NewPrivateKey()
 	if err != nil {
 		return n, err
 	}

lnwire/message_test.go

@@ -7,14 +7,14 @@ import (
 	"image/color"
 	"io"
 	"math"
-	"math/big"
 	"math/rand"
 	"net"
 	"sync"
 	"testing"
 
-	"github.com/btcsuite/btcd/btcec"
-	"github.com/btcsuite/btcutil"
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
+	"github.com/btcsuite/btcd/btcutil"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/tor"
 	"github.com/stretchr/testify/mock"
@@ -25,10 +25,7 @@ const deliveryAddressMaxSize = 34
 const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
 
 var (
-	testSig = &btcec.Signature{
-		R: new(big.Int),
-		S: new(big.Int),
-	}
+	testSig        = &ecdsa.Signature{}
 	testNodeSig, _ = lnwire.NewSigFromSignature(testSig)
 
 	testNumExtraBytes = 1000
@@ -865,7 +862,7 @@ func randRawKey(t testing.TB) [33]byte {
 
 	var n [33]byte
 
-	priv, err := btcec.NewPrivateKey(btcec.S256())
+	priv, err := btcec.NewPrivateKey()
 	require.NoError(t, err, "failed to create privKey")
 
 	copy(n[:], priv.PubKey().SerializeCompressed())
@@ -876,7 +873,7 @@ func randRawKey(t testing.TB) [33]byte {
 func randPubKey(t testing.TB) *btcec.PublicKey {
 	t.Helper()
 
-	priv, err := btcec.NewPrivateKey(btcec.S256())
+	priv, err := btcec.NewPrivateKey()
 	require.NoError(t, err, "failed to create pubkey")
 
 	return priv.PubKey()

lnwire/msat.go

@@ -3,7 +3,7 @@ package lnwire
 import (
 	"fmt"
 
-	"github.com/btcsuite/btcutil"
+	"github.com/btcsuite/btcd/btcutil"
 )
 
 const (

lnwire/msat_test.go

@@ -3,7 +3,7 @@ package lnwire
 import (
 	"testing"
 
-	"github.com/btcsuite/btcutil"
+	"github.com/btcsuite/btcd/btcutil"
 )
 
 func TestMilliSatoshiConversion(t *testing.T) {

lnwire/netaddress.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"net"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/wire"
 )
 

lnwire/netaddress_test.go

@@ -5,7 +5,7 @@ import (
 	"net"
 	"testing"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
 )
 
 func TestNetAddressDisplay(t *testing.T) {
@@ -17,7 +17,7 @@ func TestNetAddressDisplay(t *testing.T) {
 		t.Fatalf("unable to decode str: %v", err)
 	}
 
-	pubKey, err := btcec.ParsePubKey(pubHex, btcec.S256())
+	pubKey, err := btcec.ParsePubKey(pubHex)
 	if err != nil {
 		t.Fatalf("unable to parse pubkey: %v", err)
 	}

lnwire/open_channel.go

@@ -4,9 +4,9 @@ import (
 	"bytes"
 	"io"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
-	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/tlv"
 )
 

lnwire/revoke_and_ack.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"io"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
 )
 
 // RevokeAndAck is sent by either side once a CommitSig message has been

lnwire/signature.go

@@ -3,14 +3,14 @@ package lnwire
 import (
 	"fmt"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
 	"github.com/lightningnetwork/lnd/input"
 )
 
 // Sig is a fixed-sized ECDSA signature. Unlike Bitcoin, we use fixed sized
 // signatures on the wire, instead of DER encoded signatures. This type
 // provides several methods to convert to/from a regular Bitcoin DER encoded
-// signature (raw bytes and *btcec.Signature).
+// signature (raw bytes and *ecdsa.Signature).
 type Sig [64]byte
 
 // NewSigFromRawSignature returns a Sig from a Bitcoin raw signature encoded in
@@ -27,7 +27,7 @@ func NewSigFromRawSignature(sig []byte) (Sig, error) {
 	// which means the length of R is the 4th byte and the length of S
 	// is the second byte after R ends. 0x02 signifies a length-prefixed,
 	// zero-padded, big-endian bigint. 0x30 signifies a DER signature.
-	// See the Serialize() method for btcec.Signature for details.
+	// See the Serialize() method for ecdsa.Signature for details.
 	rLen := sig[3]
 	sLen := sig[5+rLen]
 
@@ -64,7 +64,7 @@ func NewSigFromRawSignature(sig []byte) (Sig, error) {
 }
 
 // NewSigFromSignature creates a new signature as used on the wire, from an
-// existing btcec.Signature.
+// existing ecdsa.Signature.
 func NewSigFromSignature(e input.Signature) (Sig, error) {
 	if e == nil {
 		return Sig{}, fmt.Errorf("cannot decode empty signature")
@@ -72,7 +72,7 @@ func NewSigFromSignature(e input.Signature) (Sig, error) {
 
 	// Nil is still a valid interface, apparently. So we need a more
 	// explicit check here.
-	if ecsig, ok := e.(*btcec.Signature); ok && ecsig == nil {
+	if ecsig, ok := e.(*ecdsa.Signature); ok && ecsig == nil {
 		return Sig{}, fmt.Errorf("cannot decode empty signature")
 	}
 
@@ -80,12 +80,12 @@ func NewSigFromSignature(e input.Signature) (Sig, error) {
 	return NewSigFromRawSignature(e.Serialize())
 }
 
-// ToSignature converts the fixed-sized signature to a btcec.Signature objects
+// ToSignature converts the fixed-sized signature to a ecdsa.Signature objects
 // which can be used for signature validation checks.
-func (b *Sig) ToSignature() (*btcec.Signature, error) {
+func (b *Sig) ToSignature() (*ecdsa.Signature, error) {
 	// Parse the signature with strict checks.
 	sigBytes := b.ToSignatureBytes()
-	sig, err := btcec.ParseDERSignature(sigBytes, btcec.S256())
+	sig, err := ecdsa.ParseDERSignature(sigBytes)
 	if err != nil {
 		return nil, err
 	}

lnwire/signature_test.go

@@ -5,7 +5,8 @@ import (
 	"math/big"
 	"testing"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
 )
 
 func TestSignatureSerializeDeserialize(t *testing.T) {
@@ -13,8 +14,8 @@ func TestSignatureSerializeDeserialize(t *testing.T) {
 
 	// Local-scoped closure to serialize and deserialize a Signature and
 	// check for errors as well as check if the results are correct.
-	signatureSerializeDeserialize := func(e btcec.Signature) error {
-		sig, err := NewSigFromSignature(&e)
+	signatureSerializeDeserialize := func(e *ecdsa.Signature) error {
+		sig, err := NewSigFromSignature(e)
 		if err != nil {
 			return err
 		}
@@ -24,67 +25,70 @@ func TestSignatureSerializeDeserialize(t *testing.T) {
 			return err
 		}
 
-		if e.R.Cmp(e2.R) != 0 {
-			return fmt.Errorf("Pre/post-serialize Rs don't match"+
-				": %s, %s", e.R, e2.R)
-		}
-		if e.S.Cmp(e2.S) != 0 {
-			return fmt.Errorf("Pre/post-serialize Ss don't match"+
-				": %s, %s", e.S, e2.S)
+		if !e.IsEqual(e2) {
+			return fmt.Errorf("pre/post-serialize sigs don't " +
+				"match")
 		}
 		return nil
 	}
 
-	sig := btcec.Signature{}
-
 	// Check R = N-1, S = 128.
-	sig.R = big.NewInt(1) // Allocate a big.Int before we call .Sub.
-	sig.R.Sub(btcec.S256().N, sig.R)
-	sig.S = big.NewInt(128)
+	r := big.NewInt(1) // Allocate a big.Int before we call .Sub.
+	r.Sub(btcec.S256().N, r)
+	rScalar := new(btcec.ModNScalar)
+	rScalar.SetByteSlice(r.Bytes())
+
+	sig := ecdsa.NewSignature(rScalar, new(btcec.ModNScalar).SetInt(128))
 	err := signatureSerializeDeserialize(sig)
 	if err != nil {
 		t.Fatalf("R = N-1, S = 128: %s", err.Error())
 	}
 
 	// Check R = N-1, S = 127.
-	sig.S = big.NewInt(127)
+	sig = ecdsa.NewSignature(rScalar, new(btcec.ModNScalar).SetInt(127))
 	err = signatureSerializeDeserialize(sig)
 	if err != nil {
 		t.Fatalf("R = N-1, S = 127: %s", err.Error())
 	}
 
 	// Check R = N-1, S = N>>1.
-	sig.S.Set(btcec.S256().N)
-	sig.S.Rsh(sig.S, 1)
+	s := new(big.Int).Set(btcec.S256().N)
+	s.Rsh(s, 1)
+	sScalar := new(btcec.ModNScalar)
+	sScalar.SetByteSlice(s.Bytes())
+	sig = ecdsa.NewSignature(rScalar, sScalar)
 	err = signatureSerializeDeserialize(sig)
 	if err != nil {
 		t.Fatalf("R = N-1, S = N>>1: %s", err.Error())
 	}
 
 	// Check R = N-1, S = N.
-	sig.S.Set(btcec.S256().N)
+	s = new(big.Int).Set(btcec.S256().N)
+	overflow := sScalar.SetByteSlice(s.Bytes())
+	if !overflow {
+		t.Fatalf("Expect ModNScalar to overflow when setting N but " +
+			"didn't")
+	}
+	sig = ecdsa.NewSignature(rScalar, sScalar)
 	err = signatureSerializeDeserialize(sig)
-	if err.Error() != "signature S isn't 1 or more" {
+	if err.Error() != "invalid signature: S is 0" {
 		t.Fatalf("R = N-1, S = N should become R = N-1, S = 0: %s",
 			err.Error())
 	}
 
 	// Check R = N-1, S = N-1.
-	sig.S.Sub(sig.S, big.NewInt(1))
+	s = new(big.Int).Set(btcec.S256().N)
+	s.Sub(s, big.NewInt(1))
+	sScalar.SetByteSlice(s.Bytes())
+	sig = ecdsa.NewSignature(rScalar, sScalar)
 	err = signatureSerializeDeserialize(sig)
-	if err.Error() != "Pre/post-serialize Ss don't match: 115792089237316"+
-		"195423570985008687907852837564279074904382605163141518161494"+
-		"336, 1" {
+	if err.Error() != "pre/post-serialize sigs don't match" {
 		t.Fatalf("R = N-1, S = N-1 should become R = N-1, S = 1: %s",
 			err.Error())
 	}
 
 	// Check R = 2N, S = 128
-	sig.R.Mul(btcec.S256().N, big.NewInt(2))
-	sig.S.Set(big.NewInt(127))
-	err = signatureSerializeDeserialize(sig)
-	if err.Error() != "R is over 32 bytes long without padding" {
-		t.Fatalf("R = 2N, S = 128, R should be over 32 bytes: %s",
-			err.Error())
-	}
+	// This cannot be tested anymore since the new ecdsa package creates
+	// the signature from ModNScalar values which don't allow setting a
+	// value larger than N (hence the name mod n).
 }

lnwire/writer.go

@@ -9,9 +9,9 @@ import (
 	"math"
 	"net"
 
-	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/tor"
 )
 

lnwire/writer_test.go

@@ -8,9 +8,9 @@ import (
 	"net"
 	"testing"
 
+	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/tor"
 	"github.com/stretchr/testify/require"
 )