crypto: add btcec fallback for sign/recover without cgo

crypto/crypto.go

@@ -23,7 +23,6 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"errors"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"math/big"
@@ -32,7 +31,6 @@ import (
 	"github.com/btcsuite/btcd/btcec"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto/ecies"
-	"github.com/ethereum/go-ethereum/crypto/secp256k1"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
 	"github.com/ethereum/go-ethereum/rlp"
 	"golang.org/x/crypto/ripemd160"
@@ -83,10 +81,6 @@ func Ripemd160(data []byte) []byte {
 	return ripemd.Sum(nil)
 }
 
-func Ecrecover(hash, sig []byte) ([]byte, error) {
-	return secp256k1.RecoverPubkey(hash, sig)
-}
-
 // New methods using proper ecdsa keys from the stdlib
 func ToECDSA(key []byte) *ecdsa.PrivateKey {
 	if len(key) == 0 {
@@ -183,27 +177,6 @@ func ValidateSignatureValues(v byte, r, s *big.Int, homestead bool) bool {
 	}
 }
 
-func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
-	s, err := Ecrecover(hash, sig)
-	if err != nil {
-		return nil, err
-	}
-
-	x, y := elliptic.Unmarshal(btcec.S256(), s)
-	return &ecdsa.PublicKey{Curve: btcec.S256(), X: x, Y: y}, nil
-}
-
-func Sign(hash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
-	if len(hash) != 32 {
-		return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(hash))
-	}
-
-	seckey := common.LeftPadBytes(prv.D.Bytes(), prv.Params().BitSize/8)
-	defer zeroBytes(seckey)
-	sig, err = secp256k1.Sign(hash, seckey)
-	return
-}
-
 func Encrypt(pub *ecdsa.PublicKey, message []byte) ([]byte, error) {
 	return ecies.Encrypt(rand.Reader, ecies.ImportECDSAPublic(pub), message, nil, nil)
 }

crypto/secp256k1/secp256_test.go

@@ -177,21 +177,6 @@ func TestZeroPrivkey(t *testing.T) {
 	}
 }
 
-// Useful when the underlying libsecp256k1 API changes to quickly
-// check only recover function without use of signature function
-func TestRecoverSanity(t *testing.T) {
-	msg, _ := hex.DecodeString("ce0677bb30baa8cf067c88db9811f4333d131bf8bcf12fe7065d211dce971008")
-	sig, _ := hex.DecodeString("90f27b8b488db00b00606796d2987f6a5f59ae62ea05effe84fef5b8b0e549984a691139ad57a3f0b906637673aa2f63d1f55cb1a69199d4009eea23ceaddc9301")
-	pubkey1, _ := hex.DecodeString("04e32df42865e97135acfb65f3bae71bdc86f4d49150ad6a440b6f15878109880a0a2b2667f7e725ceea70c673093bf67663e0312623c8e091b13cf2c0f11ef652")
-	pubkey2, err := RecoverPubkey(msg, sig)
-	if err != nil {
-		t.Fatalf("recover error: %s", err)
-	}
-	if !bytes.Equal(pubkey1, pubkey2) {
-		t.Errorf("pubkey mismatch: want: %x have: %x", pubkey1, pubkey2)
-	}
-}
-
 func TestReadBits(t *testing.T) {
 	check := func(input string) {
 		want, _ := hex.DecodeString(input)

crypto/signature_cgo.go

@@ -0,0 +1,52 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// +build !nacl,!javascript,!nocgo
+
+package crypto
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"fmt"
+
+	"github.com/btcsuite/btcd/btcec"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto/secp256k1"
+)
+
+func Ecrecover(hash, sig []byte) ([]byte, error) {
+	return secp256k1.RecoverPubkey(hash, sig)
+}
+
+func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
+	s, err := Ecrecover(hash, sig)
+	if err != nil {
+		return nil, err
+	}
+
+	x, y := elliptic.Unmarshal(btcec.S256(), s)
+	return &ecdsa.PublicKey{Curve: btcec.S256(), X: x, Y: y}, nil
+}
+
+func Sign(hash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
+	if len(hash) != 32 {
+		return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(hash))
+	}
+	seckey := common.LeftPadBytes(prv.D.Bytes(), prv.Params().BitSize/8)
+	defer zeroBytes(seckey)
+	return secp256k1.Sign(hash, seckey)
+}

crypto/signature_nocgo.go

@@ -0,0 +1,63 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// +build nacl javascript nocgo
+
+package crypto
+
+import (
+	"crypto/ecdsa"
+	"fmt"
+
+	"github.com/btcsuite/btcd/btcec"
+)
+
+func Ecrecover(hash, sig []byte) ([]byte, error) {
+	pub, err := SigToPub(hash, sig)
+	if err != nil {
+		return nil, err
+	}
+	bytes := (*btcec.PublicKey)(pub).SerializeUncompressed()
+	return bytes, err
+}
+
+func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
+	// Convert to btcec input format with 'recovery id' v at the beginning.
+	btcsig := make([]byte, 65)
+	btcsig[0] = sig[64] + 27
+	copy(btcsig[1:], sig)
+
+	pub, _, err := btcec.RecoverCompact(btcec.S256(), btcsig, hash)
+	return (*ecdsa.PublicKey)(pub), err
+}
+
+func Sign(hash []byte, prv *ecdsa.PrivateKey) ([]byte, error) {
+	if len(hash) != 32 {
+		return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(hash))
+	}
+	if prv.Curve != btcec.S256() {
+		return nil, fmt.Errorf("private key curve is not secp256k1")
+	}
+	sig, err := btcec.SignCompact(btcec.S256(), (*btcec.PrivateKey)(prv), hash, false)
+	if err != nil {
+		return nil, err
+	}
+	// Convert to Ethereum signature format with 'recovery id' v at the end.
+	v := sig[0] - 27
+	copy(sig, sig[1:])
+	sig[64] = v
+	return sig, nil
+}

crypto/signature_test.go

@@ -0,0 +1,36 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package crypto
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+)
+
+func TestRecoverSanity(t *testing.T) {
+	msg, _ := hex.DecodeString("ce0677bb30baa8cf067c88db9811f4333d131bf8bcf12fe7065d211dce971008")
+	sig, _ := hex.DecodeString("90f27b8b488db00b00606796d2987f6a5f59ae62ea05effe84fef5b8b0e549984a691139ad57a3f0b906637673aa2f63d1f55cb1a69199d4009eea23ceaddc9301")
+	pubkey1, _ := hex.DecodeString("04e32df42865e97135acfb65f3bae71bdc86f4d49150ad6a440b6f15878109880a0a2b2667f7e725ceea70c673093bf67663e0312623c8e091b13cf2c0f11ef652")
+	pubkey2, err := Ecrecover(msg, sig)
+	if err != nil {
+		t.Fatalf("recover error: %s", err)
+	}
+	if !bytes.Equal(pubkey1, pubkey2) {
+		t.Errorf("pubkey mismatch: want: %x have: %x", pubkey1, pubkey2)
+	}
+}