2017-10-31 15:24:11 -07:00
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// Copyright 2016 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package types
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import (
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"crypto/ecdsa"
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"errors"
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"fmt"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/params"
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)
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var (
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ErrInvalidChainId = errors.New("invalid chain id for signer")
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)
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// sigCache is used to cache the derived sender and contains
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// the signer used to derive it.
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type sigCache struct {
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signer Signer
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from common.Address
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}
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// MakeSigner returns a Signer based on the given chain config and block number.
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func MakeSigner(config *params.ChainConfig, blockNumber *big.Int) Signer {
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var signer Signer
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switch {
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case config.IsEIP155(blockNumber):
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signer = NewEIP155Signer(config.ChainId)
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case config.IsHomestead(blockNumber):
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signer = HomesteadSigner{}
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default:
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signer = FrontierSigner{}
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}
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return signer
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}
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// SignTx signs the transaction using the given signer and private key
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func SignTx(tx *Transaction, s Signer, prv *ecdsa.PrivateKey) (*Transaction, error) {
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h := s.Hash(tx)
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sig, err := crypto.Sign(h[:], prv)
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if err != nil {
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return nil, err
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}
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return tx.WithSignature(s, sig)
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}
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// Sender returns the address derived from the signature (V, R, S) using secp256k1
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// elliptic curve and an error if it failed deriving or upon an incorrect
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// signature.
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//
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// Sender may cache the address, allowing it to be used regardless of
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// signing method. The cache is invalidated if the cached signer does
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// not match the signer used in the current call.
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func Sender(signer Signer, tx *Transaction) (common.Address, error) {
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if sc := tx.from.Load(); sc != nil {
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sigCache := sc.(sigCache)
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// If the signer used to derive from in a previous
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// call is not the same as used current, invalidate
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// the cache.
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if sigCache.signer.Equal(signer) {
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return sigCache.from, nil
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}
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}
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addr, err := signer.Sender(tx)
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if err != nil {
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return common.Address{}, err
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}
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tx.from.Store(sigCache{signer: signer, from: addr})
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return addr, nil
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}
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// Signer encapsulates transaction signature handling. Note that this interface is not a
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// stable API and may change at any time to accommodate new protocol rules.
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type Signer interface {
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// Sender returns the sender address of the transaction.
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Sender(tx *Transaction) (common.Address, error)
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// SignatureValues returns the raw R, S, V values corresponding to the
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// given signature.
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SignatureValues(tx *Transaction, sig []byte) (r, s, v *big.Int, err error)
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// Hash returns the hash to be signed.
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Hash(tx *Transaction) common.Hash
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// Equal returns true if the given signer is the same as the receiver.
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Equal(Signer) bool
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}
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// EIP155Transaction implements Signer using the EIP155 rules.
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type EIP155Signer struct {
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chainId, chainIdMul *big.Int
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}
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func NewEIP155Signer(chainId *big.Int) EIP155Signer {
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if chainId == nil {
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chainId = new(big.Int)
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}
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return EIP155Signer{
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chainId: chainId,
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chainIdMul: new(big.Int).Mul(chainId, big.NewInt(2)),
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}
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}
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func (s EIP155Signer) Equal(s2 Signer) bool {
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eip155, ok := s2.(EIP155Signer)
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return ok && eip155.chainId.Cmp(s.chainId) == 0
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}
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var big8 = big.NewInt(8)
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func (s EIP155Signer) Sender(tx *Transaction) (common.Address, error) {
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if tx.IsPrivate() {
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return HomesteadSigner{}.Sender(tx)
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}
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2017-10-31 15:24:11 -07:00
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if !tx.Protected() {
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return HomesteadSigner{}.Sender(tx)
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}
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if tx.ChainId().Cmp(s.chainId) != 0 {
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return common.Address{}, ErrInvalidChainId
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}
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V := new(big.Int).Sub(tx.data.V, s.chainIdMul)
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V.Sub(V, big8)
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2018-04-22 19:06:23 -07:00
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return recoverPlain(s.Hash(tx), tx.data.R, tx.data.S, V, true, tx.IsPrivate())
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2017-10-31 15:24:11 -07:00
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}
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// WithSignature returns a new transaction with the given signature. This signature
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// needs to be in the [R || S || V] format where V is 0 or 1.
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func (s EIP155Signer) SignatureValues(tx *Transaction, sig []byte) (R, S, V *big.Int, err error) {
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if tx.IsPrivate() {
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return HomesteadSigner{}.SignatureValues(tx, sig)
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}
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2017-10-31 15:24:11 -07:00
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R, S, V, err = HomesteadSigner{}.SignatureValues(tx, sig)
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if err != nil {
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return nil, nil, nil, err
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}
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if s.chainId.Sign() != 0 {
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V = big.NewInt(int64(sig[64] + 35))
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V.Add(V, s.chainIdMul)
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}
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return R, S, V, nil
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}
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// Hash returns the hash to be signed by the sender.
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// It does not uniquely identify the transaction.
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func (s EIP155Signer) Hash(tx *Transaction) common.Hash {
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return rlpHash([]interface{}{
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tx.data.AccountNonce,
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tx.data.Price,
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tx.data.GasLimit,
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tx.data.Recipient,
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tx.data.Amount,
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tx.data.Payload,
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s.chainId, uint(0), uint(0),
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})
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}
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// HomesteadTransaction implements TransactionInterface using the
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// homestead rules.
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type HomesteadSigner struct{ FrontierSigner }
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func (s HomesteadSigner) Equal(s2 Signer) bool {
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_, ok := s2.(HomesteadSigner)
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return ok
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}
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// SignatureValues returns signature values. This signature
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// needs to be in the [R || S || V] format where V is 0 or 1.
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func (hs HomesteadSigner) SignatureValues(tx *Transaction, sig []byte) (r, s, v *big.Int, err error) {
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return hs.FrontierSigner.SignatureValues(tx, sig)
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}
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func (hs HomesteadSigner) Sender(tx *Transaction) (common.Address, error) {
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return recoverPlain(hs.Hash(tx), tx.data.R, tx.data.S, tx.data.V, true, tx.IsPrivate())
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}
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type FrontierSigner struct{}
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func (s FrontierSigner) Equal(s2 Signer) bool {
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_, ok := s2.(FrontierSigner)
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return ok
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}
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// SignatureValues returns signature values. This signature
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// needs to be in the [R || S || V] format where V is 0 or 1.
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func (fs FrontierSigner) SignatureValues(tx *Transaction, sig []byte) (r, s, v *big.Int, err error) {
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if len(sig) != 65 {
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panic(fmt.Sprintf("wrong size for signature: got %d, want 65", len(sig)))
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}
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r = new(big.Int).SetBytes(sig[:32])
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s = new(big.Int).SetBytes(sig[32:64])
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if tx.IsPrivate() {
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v = new(big.Int).SetBytes([]byte{sig[64] + 37})
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} else {
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v = new(big.Int).SetBytes([]byte{sig[64] + 27})
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}
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return r, s, v, nil
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}
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// Hash returns the hash to be signed by the sender.
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// It does not uniquely identify the transaction.
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func (fs FrontierSigner) Hash(tx *Transaction) common.Hash {
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return rlpHash([]interface{}{
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tx.data.AccountNonce,
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tx.data.Price,
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tx.data.GasLimit,
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tx.data.Recipient,
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tx.data.Amount,
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tx.data.Payload,
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})
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}
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func (fs FrontierSigner) Sender(tx *Transaction) (common.Address, error) {
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return recoverPlain(fs.Hash(tx), tx.data.R, tx.data.S, tx.data.V, false, tx.IsPrivate())
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}
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func recoverPlain(sighash common.Hash, R, S, Vb *big.Int, homestead bool, isPrivate bool) (common.Address, error) {
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if Vb.BitLen() > 8 {
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return common.Address{}, ErrInvalidSig
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}
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var offset uint64
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if isPrivate {
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offset = 37
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} else {
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offset = 27
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}
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V := byte(Vb.Uint64() - offset)
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if !crypto.ValidateSignatureValues(V, R, S, homestead) {
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return common.Address{}, ErrInvalidSig
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}
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// encode the snature in uncompressed format
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r, s := R.Bytes(), S.Bytes()
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sig := make([]byte, 65)
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copy(sig[32-len(r):32], r)
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copy(sig[64-len(s):64], s)
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sig[64] = V
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// recover the public key from the snature
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pub, err := crypto.Ecrecover(sighash[:], sig)
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if err != nil {
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return common.Address{}, err
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}
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if len(pub) == 0 || pub[0] != 4 {
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return common.Address{}, errors.New("invalid public key")
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}
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var addr common.Address
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copy(addr[:], crypto.Keccak256(pub[1:])[12:])
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return addr, nil
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}
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// deriveChainId derives the chain id from the given v parameter
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func deriveChainId(v *big.Int) *big.Int {
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if v.BitLen() <= 64 {
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v := v.Uint64()
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if v == 27 || v == 28 {
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return new(big.Int)
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}
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// TODO(joel): this given v = 37 / 38 this constrains us to chain id 1
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return new(big.Int).SetUint64((v - 35) / 2)
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}
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v = new(big.Int).Sub(v, big.NewInt(35))
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return v.Div(v, big.NewInt(2))
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}
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