Merge branch 'ebuchman-fix_ecrecover' into develop

2 files changed, 31 insertions, 16 deletions

diff --git a/core/vm/address.go b/core/vm/address.go
index 215f4bc8f..0b3a95dd0 100644
--- a/core/vm/address.go
+++ b/core/vm/address.go
@@ -3,8 +3,8 @@ package vm
 import (
 	"math/big"
 
-	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
 )
 
 type Address interface {
@@ -61,15 +61,32 @@ func ripemd160Func(in []byte) []byte {
 	return common.LeftPadBytes(crypto.Ripemd160(in), 32)
 }
 
+const ecRecoverInputLength = 128
+
 func ecrecoverFunc(in []byte) []byte {
-	// In case of an invalid sig. Defaults to return nil
-	defer func() { recover() }()
+	// "in" is (hash, v, r, s), each 32 bytes
+	// but for ecrecover we want (r, s, v)
+	if len(in) < ecRecoverInputLength {
+		return nil
+	}
 
-	hash := in[:32]
-	v := common.BigD(in[32:64]).Bytes()[0] - 27
-	sig := append(in[64:], v)
+	// Treat V as a 256bit integer
+	v := new(big.Int).Sub(common.Bytes2Big(in[32:64]), big.NewInt(27))
+	// Ethereum requires V to be either 0 or 1 => (27 || 28)
+	if !(v.Cmp(Zero) == 0 || v.Cmp(One) == 0) {
+		return nil
+	}
+
+	// v needs to be moved to the end
+	rsv := append(in[64:128], byte(v.Uint64()))
+	pubKey := crypto.Ecrecover(in[:32], rsv)
+	// make sure the public key is a valid one
+	if pubKey == nil || len(pubKey) != 65 {
+		return nil
+	}
 
-	return common.LeftPadBytes(crypto.Sha3(crypto.Ecrecover(append(hash, sig...))[1:])[12:], 32)
+	// the first byte of pubkey is bitcoin heritage
+	return common.LeftPadBytes(crypto.Sha3(pubKey[1:])[12:], 32)
 }
 
 func memCpy(in []byte) []byte {
diff --git a/crypto/crypto.go b/crypto/crypto.go
index 442942c6c..9a1559fbf 100644
--- a/crypto/crypto.go
+++ b/crypto/crypto.go
@@ -68,13 +68,8 @@ func Ripemd160(data []byte) []byte {
 	return ripemd.Sum(nil)
 }
 
-func Ecrecover(data []byte) []byte {
-	var in = struct {
-		hash []byte
-		sig  []byte
-	}{data[:32], data[32:]}
-
-	r, _ := secp256k1.RecoverPubkey(in.hash, in.sig)
+func Ecrecover(hash, sig []byte) []byte {
+	r, _ := secp256k1.RecoverPubkey(hash, sig)
 
 	return r
 }
@@ -151,9 +146,12 @@ func GenerateKey() (*ecdsa.PrivateKey, error) {
 }
 
 func SigToPub(hash, sig []byte) *ecdsa.PublicKey {
-	s := Ecrecover(append(hash, sig...))
-	x, y := elliptic.Unmarshal(S256(), s)
+	s := Ecrecover(hash, sig)
+	if s == nil || len(s) != 65 {
+		return nil
+	}
 
+	x, y := elliptic.Unmarshal(S256(), s)
 	return &ecdsa.PublicKey{S256(), x, y}
 }