// 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 types
import (
"crypto/ecdsa"
"errors"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/params"
)
var (
ErrInvalidChainId = errors.New("invalid chain id for signer")
)
// sigCache is used to cache the derived sender and contains
// the signer used to derive it.
type sigCache struct {
signer Signer
from common.Address
}
// MakeSigner returns a Signer based on the given chain config and block number.
func MakeSigner(config *params.ChainConfig, blockNumber *big.Int) Signer {
var signer Signer
switch {
case config.IsEIP155(blockNumber):
signer = NewEIP155Signer(config.ChainId)
case config.IsHomestead(blockNumber):
signer = HomesteadSigner{}
default:
signer = FrontierSigner{}
}
return signer
}
// SignTx signs the transaction using the given signer and private key
func SignTx(tx *Transaction, s Signer, prv *ecdsa.PrivateKey) (*Transaction, error) {
h := s.Hash(tx)
sig, err := crypto.Sign(h[:], prv)
if err != nil {
return nil, err
}
return tx.WithSignature(s, sig)
}
// Sender returns the address derived from the signature (V, R, S) using secp256k1
// elliptic curve and an error if it failed deriving or upon an incorrect
// signature.
//
// Sender may cache the address, allowing it to be used regardless of
// signing method. The cache is invalidated if the cached signer does
// not match the signer used in the current call.
func Sender(signer Signer, tx *Transaction) (common.Address, error) {
if sc := tx.from.Load(); sc != nil {
sigCache := sc.(sigCache)
// If the signer used to derive from in a previous
// call is not the same as used current, invalidate
// the cache.
if sigCache.signer.Equal(signer) {
return sigCache.from, nil
}
}
addr, err := signer.Sender(tx)
if err != nil {
return common.Address{}, err
}
tx.from.Store(sigCache{signer: signer, from: addr})
return addr, nil
}
// Signer encapsulates transaction signature handling. Note that this interface is not a
// stable API and may change at any time to accommodate new protocol rules.
type Signer interface {
// Sender returns the sender address of the transaction.
Sender(tx *Transaction) (common.Address, error)
// SignatureValues returns the raw R, S, V values corresponding to the
// given signature.
SignatureValues(tx *Transaction, sig []byte) (r, s, v *big.Int, err error)
// Hash returns the hash to be signed.
Hash(tx *Transaction) common.Hash
// Equal returns true if the given signer is the same as the receiver.
Equal(Signer) bool
}
// EIP155Transaction implements Signer using the EIP155 rules.
type EIP155Signer struct {
chainId, chainIdMul *big.Int
}
func NewEIP155Signer(chainId *big.Int) EIP155Signer {
if chainId == nil {
chainId = new(big.Int)
}
return EIP155Signer{
chainId: chainId,
chainIdMul: new(big.Int).Mul(chainId, big.NewInt(2)),
}
}
func (s EIP155Signer) Equal(s2 Signer) bool {
eip155, ok := s2.(EIP155Signer)
return ok && eip155.chainId.Cmp(s.chainId) == 0
}
var big8 = big.NewInt(8)
func (s EIP155Signer) Sender(tx *Transaction) (common.Address, error) {
if !tx.Protected() {
return HomesteadSigner{}.Sender(tx)
}
if tx.ChainId().Cmp(s.chainId) != 0 {
return common.Address{}, ErrInvalidChainId
}
V := new(big.Int).Sub(tx.data.V, s.chainIdMul)
V.Sub(V, big8)
return recoverPlain(s.Hash(tx), tx.data.R, tx.data.S, V, true)
}
// WithSignature returns a new transaction with the given signature. This signature
// needs to be in the [R || S || V] format where V is 0 or 1.
func (s EIP155Signer) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
R, S, V, err = HomesteadSigner{}.SignatureValues(tx, sig)
if err != nil {
return nil, nil, nil, err
}
if s.chainId.Sign() != 0 {
V = big.NewInt(int64(sig[64] + 35))
V.Add(V, s.chainIdMul)
}
return R, S, V, nil
}
// Hash returns the hash to be signed by the sender.
// It does not uniquely identify the transaction.
func (s EIP155Signer) Hash(tx *Transaction) common.Hash {
return rlpHash([]interface{}{
tx.data.AccountNonce,
tx.data.Price,
tx.data.GasLimit,
tx.data.Recipient,
tx.data.Amount,
tx.data.Payload,
s.chainId, uint(0), uint(0),
})
}
// HomesteadTransaction implements TransactionInterface using the
// homestead rules.
type HomesteadSigner struct{ FrontierSigner }
func (s HomesteadSigner) Equal(s2 Signer) bool {
_, ok := s2.(HomesteadSigner)
return ok
}
// SignatureValues returns signature values. This signature
// needs to be in the [R || S || V] format where V is 0 or 1.
func (hs HomesteadSigner) SignatureValues(tx *Transaction, sig []byte) (r, s, v *big.Int, err error) {
return hs.FrontierSigner.SignatureValues(tx, sig)
}
func (hs HomesteadSigner) Sender(tx *Transaction) (common.Address, error) {
return recoverPlain(hs.Hash(tx), tx.data.R, tx.data.S, tx.data.V, true)
}
type FrontierSigner struct{}
func (s FrontierSigner) Equal(s2 Signer) bool {
_, ok := s2.(FrontierSigner)
return ok
}
// SignatureValues returns signature values. This signature
// needs to be in the [R || S || V] format where V is 0 or 1.
func (fs FrontierSigner) SignatureValues(tx *Transaction, sig []byte) (r, s, v *big.Int, err error) {
if len(sig) != 65 {
panic(fmt.Sprintf("wrong size for signature: got %d, want 65", len(sig)))
}
r = new(big.Int).SetBytes(sig[:32])
s = new(big.Int).SetBytes(sig[32:64])
v = new(big.Int).SetBytes([]byte{sig[64] + 27})
return r, s, v, nil
}
// Hash returns the hash to be signed by the sender.
// It does not uniquely identify the transaction.
func (fs FrontierSigner) Hash(tx *Transaction) common.Hash {
return rlpHash([]interface{}{
tx.data.AccountNonce,
tx.data.Price,
tx.data.GasLimit,
tx.data.Recipient,
tx.data.Amount,
tx.data.Payload,
})
}
func (fs FrontierSigner) Sender(tx *Transaction) (common.Address, error) {
return recoverPlain(fs.Hash(tx), tx.data.R, tx.data.S, tx.data.V, false)
}
func recoverPlain(sighash common.Hash, R, S, Vb *big.Int, homestead bool) (common.Address, error) {
if Vb.BitLen() > 8 {
return common.Address{}, ErrInvalidSig
}
V := byte(Vb.Uint64() - 27)
if !crypto.ValidateSignatureValues(V, R, S, homestead) {
return common.Address{}, ErrInvalidSig
}
// encode the snature in uncompressed format
r, s := R.Bytes(), S.Bytes()
sig := make([]byte, 65)
copy(sig[32-len(r):32], r)
copy(sig[64-len(s):64], s)
sig[64] = V
// recover the public key from the snature
pub, err := crypto.Ecrecover(sighash[:], sig)
if err != nil {
return common.Address{}, err
}
if len(pub) == 0 || pub[0] != 4 {
return common.Address{}, errors.New("invalid public key")
}
var addr common.Address
copy(addr[:], crypto.Keccak256(pub[1:])[12:])
return addr, nil
}
// deriveChainId derives the chain id from the given v parameter
func deriveChainId(v *big.Int) *big.Int {
if v.BitLen() <= 64 {
v := v.Uint64()
if v == 27 || v == 28 {
return new(big.Int)
}
return new(big.Int).SetUint64((v - 35) / 2)
}
v = new(big.Int).Sub(v, big.NewInt(35))
return v.Div(v, big.NewInt(2))
}
