crypto: use decred secp256k1 directly (#30595)

Use `github.com/decred/dcrd/dcrec/secp256k1/v4` directly rather than
`github.com/btcsuite/btcd/btcec/v2` which is just a wrapper around the
underlying decred library. Inspired by
cosmos/cosmos-sdk#15018

`github.com/btcsuite/btcd/btcec/v2` has a very annoying breaking change
when upgrading from `v2.3.3` to `v2.3.4`. The easiest way to workaround
this is to just remove the wrapper.

Would be very nice if you could backport this to the release branches.

References:
- btcsuite/btcd#2221
- cometbft/cometbft#4294
- cometbft/cometbft#3728
- zeta-chain/node#2934

crypto/signature_nocgo.go

@@ -25,8 +25,8 @@ import (
 	"fmt"
 	"math/big"
 
-	"github.com/btcsuite/btcd/btcec/v2"
-	btc_ecdsa "github.com/btcsuite/btcd/btcec/v2/ecdsa"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
+	decred_ecdsa "github.com/decred/dcrd/dcrec/secp256k1/v4/ecdsa"
 )
 
 // Ecrecover returns the uncompressed public key that created the given signature.
@@ -39,16 +39,16 @@ func Ecrecover(hash, sig []byte) ([]byte, error) {
 	return bytes, err
 }
 
-func sigToPub(hash, sig []byte) (*btcec.PublicKey, error) {
+func sigToPub(hash, sig []byte) (*secp256k1.PublicKey, error) {
 	if len(sig) != SignatureLength {
 		return nil, errors.New("invalid signature")
 	}
-	// Convert to btcec input format with 'recovery id' v at the beginning.
+	// Convert to secp256k1 input format with 'recovery id' v at the beginning.
 	btcsig := make([]byte, SignatureLength)
 	btcsig[0] = sig[RecoveryIDOffset] + 27
 	copy(btcsig[1:], sig)
 
-	pub, _, err := btc_ecdsa.RecoverCompact(btcsig, hash)
+	pub, _, err := decred_ecdsa.RecoverCompact(btcsig, hash)
 	return pub, err
 }
 
@@ -82,13 +82,13 @@ func Sign(hash []byte, prv *ecdsa.PrivateKey) ([]byte, error) {
 	if prv.Curve != S256() {
 		return nil, errors.New("private key curve is not secp256k1")
 	}
-	// ecdsa.PrivateKey -> btcec.PrivateKey
-	var priv btcec.PrivateKey
+	// ecdsa.PrivateKey -> secp256k1.PrivateKey
+	var priv secp256k1.PrivateKey
 	if overflow := priv.Key.SetByteSlice(prv.D.Bytes()); overflow || priv.Key.IsZero() {
 		return nil, errors.New("invalid private key")
 	}
 	defer priv.Zero()
-	sig := btc_ecdsa.SignCompact(&priv, hash, false) // ref uncompressed pubkey
+	sig := decred_ecdsa.SignCompact(&priv, hash, false) // ref uncompressed pubkey
 	// Convert to Ethereum signature format with 'recovery id' v at the end.
 	v := sig[0] - 27
 	copy(sig, sig[1:])
@@ -103,19 +103,19 @@ func VerifySignature(pubkey, hash, signature []byte) bool {
 	if len(signature) != 64 {
 		return false
 	}
-	var r, s btcec.ModNScalar
+	var r, s secp256k1.ModNScalar
 	if r.SetByteSlice(signature[:32]) {
 		return false // overflow
 	}
 	if s.SetByteSlice(signature[32:]) {
 		return false
 	}
-	sig := btc_ecdsa.NewSignature(&r, &s)
-	key, err := btcec.ParsePubKey(pubkey)
+	sig := decred_ecdsa.NewSignature(&r, &s)
+	key, err := secp256k1.ParsePubKey(pubkey)
 	if err != nil {
 		return false
 	}
-	// Reject malleable signatures. libsecp256k1 does this check but btcec doesn't.
+	// Reject malleable signatures. libsecp256k1 does this check but decred doesn't.
 	if s.IsOverHalfOrder() {
 		return false
 	}
@@ -127,7 +127,7 @@ func DecompressPubkey(pubkey []byte) (*ecdsa.PublicKey, error) {
 	if len(pubkey) != 33 {
 		return nil, errors.New("invalid compressed public key length")
 	}
-	key, err := btcec.ParsePubKey(pubkey)
+	key, err := secp256k1.ParsePubKey(pubkey)
 	if err != nil {
 		return nil, err
 	}
@@ -148,20 +148,20 @@ func DecompressPubkey(pubkey []byte) (*ecdsa.PublicKey, error) {
 // when constructing a PrivateKey.
 func CompressPubkey(pubkey *ecdsa.PublicKey) []byte {
 	// NOTE: the coordinates may be validated with
-	// btcec.ParsePubKey(FromECDSAPub(pubkey))
-	var x, y btcec.FieldVal
+	// secp256k1.ParsePubKey(FromECDSAPub(pubkey))
+	var x, y secp256k1.FieldVal
 	x.SetByteSlice(pubkey.X.Bytes())
 	y.SetByteSlice(pubkey.Y.Bytes())
-	return btcec.NewPublicKey(&x, &y).SerializeCompressed()
+	return secp256k1.NewPublicKey(&x, &y).SerializeCompressed()
 }
 
 // S256 returns an instance of the secp256k1 curve.
 func S256() EllipticCurve {
-	return btCurve{btcec.S256()}
+	return btCurve{secp256k1.S256()}
 }
 
 type btCurve struct {
-	*btcec.KoblitzCurve
+	*secp256k1.KoblitzCurve
 }
 
 // Marshal converts a point given as (x, y) into a byte slice.

go.mod

@@ -12,7 +12,6 @@ require (
 	github.com/aws/aws-sdk-go-v2/config v1.18.45
 	github.com/aws/aws-sdk-go-v2/credentials v1.13.43
 	github.com/aws/aws-sdk-go-v2/service/route53 v1.30.2
-	github.com/btcsuite/btcd/btcec/v2 v2.3.4
 	github.com/cespare/cp v0.1.0
 	github.com/cloudflare/cloudflare-go v0.79.0
 	github.com/cockroachdb/pebble v1.1.2
@@ -21,6 +20,7 @@ require (
 	github.com/crate-crypto/go-kzg-4844 v1.0.0
 	github.com/davecgh/go-spew v1.1.1
 	github.com/deckarep/golang-set/v2 v2.6.0
+	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1
 	github.com/donovanhide/eventsource v0.0.0-20210830082556-c59027999da0
 	github.com/dop251/goja v0.0.0-20230605162241-28ee0ee714f3
 	github.com/ethereum/c-kzg-4844 v1.0.0
@@ -102,7 +102,6 @@ require (
 	github.com/cockroachdb/tokenbucket v0.0.0-20230807174530-cc333fc44b06 // indirect
 	github.com/consensys/bavard v0.1.13 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
-	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect
 	github.com/deepmap/oapi-codegen v1.6.0 // indirect
 	github.com/dlclark/regexp2 v1.7.0 // indirect
 	github.com/garslo/gogen v0.0.0-20170306192744-1d203ffc1f61 // indirect

go.sum

@@ -92,10 +92,6 @@ github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/bits-and-blooms/bitset v1.13.0 h1:bAQ9OPNFYbGHV6Nez0tmNI0RiEu7/hxlYJRUA0wFAVE=
 github.com/bits-and-blooms/bitset v1.13.0/go.mod h1:7hO7Gc7Pp1vODcmWvKMRA9BNmbv6a/7QIWpPxHddWR8=
-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/chaincfg/chainhash v1.0.1 h1:q0rUy8C/TYNBQS1+CGKw68tLOFYSNEs0TFnxxnS9+4U=
-github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1/go.mod h1:7SFka0XMvUgj3hfZtydOrQY2mwhPclbT2snogU7SQQc=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/cp v0.1.0 h1:SE+dxFebS7Iik5LK0tsi1k9ZCxEaFX4AjQmoyA+1dJk=
 github.com/cespare/cp v0.1.0/go.mod h1:SOGHArjBr4JWaSDEVpWpo/hNg6RoKrls6Oh40hiwW+s=

tests/fuzzers/secp256k1/secp_test.go

@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/btcsuite/btcd/btcec/v2"
+	dcred_secp256k1 "github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/ethereum/go-ethereum/crypto/secp256k1"
 )
 
@@ -38,7 +38,7 @@ func Fuzz(f *testing.F) {
 func fuzz(dataP1, dataP2 []byte) {
 	var (
 		curveA = secp256k1.S256()
-		curveB = btcec.S256()
+		curveB = dcred_secp256k1.S256()
 	)
 	// first point
 	x1, y1 := curveB.ScalarBaseMult(dataP1)