// Copyright 2018 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package core
import (
"context"
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"math/big"
"reflect"
"github.com/ethereum/go-ethereum/accounts"
"github.com/ethereum/go-ethereum/accounts/keystore"
"github.com/ethereum/go-ethereum/accounts/usbwallet"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/internal/ethapi"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
)
// ExternalAPI defines the external API through which signing requests are made.
type ExternalAPI interface {
// List available accounts
List(ctx context.Context) (Accounts, error)
// New request to create a new account
New(ctx context.Context) (accounts.Account, error)
// SignTransaction request to sign the specified transaction
SignTransaction(ctx context.Context, args SendTxArgs, methodSelector *string) (*ethapi.SignTransactionResult, error)
// Sign - request to sign the given data (plus prefix)
Sign(ctx context.Context, addr common.MixedcaseAddress, data hexutil.Bytes) (hexutil.Bytes, error)
// EcRecover - request to perform ecrecover
EcRecover(ctx context.Context, data, sig hexutil.Bytes) (common.Address, error)
// Export - request to export an account
Export(ctx context.Context, addr common.Address) (json.RawMessage, error)
// Import - request to import an account
Import(ctx context.Context, keyJSON json.RawMessage) (Account, error)
}
// SignerUI specifies what method a UI needs to implement to be able to be used as a UI for the signer
type SignerUI interface {
// ApproveTx prompt the user for confirmation to request to sign Transaction
ApproveTx(request *SignTxRequest) (SignTxResponse, error)
// ApproveSignData prompt the user for confirmation to request to sign data
ApproveSignData(request *SignDataRequest) (SignDataResponse, error)
// ApproveExport prompt the user for confirmation to export encrypted Account json
ApproveExport(request *ExportRequest) (ExportResponse, error)
// ApproveImport prompt the user for confirmation to import Account json
ApproveImport(request *ImportRequest) (ImportResponse, error)
// ApproveListing prompt the user for confirmation to list accounts
// the list of accounts to list can be modified by the UI
ApproveListing(request *ListRequest) (ListResponse, error)
// ApproveNewAccount prompt the user for confirmation to create new Account, and reveal to caller
ApproveNewAccount(request *NewAccountRequest) (NewAccountResponse, error)
// ShowError displays error message to user
ShowError(message string)
// ShowInfo displays info message to user
ShowInfo(message string)
// OnApprovedTx notifies the UI about a transaction having been successfully signed.
// This method can be used by a UI to keep track of e.g. how much has been sent to a particular recipient.
OnApprovedTx(tx ethapi.SignTransactionResult)
// OnSignerStartup is invoked when the signer boots, and tells the UI info about external API location and version
// information
OnSignerStartup(info StartupInfo)
}
// SignerAPI defines the actual implementation of ExternalAPI
type SignerAPI struct {
chainID *big.Int
am *accounts.Manager
UI SignerUI
validator *Validator
}
// Metadata about a request
type Metadata struct {
Remote string `json:"remote"`
Local string `json:"local"`
Scheme string `json:"scheme"`
}
// MetadataFromContext extracts Metadata from a given context.Context
func MetadataFromContext(ctx context.Context) Metadata {
m := Metadata{"NA", "NA", "NA"} // batman
if v := ctx.Value("remote"); v != nil {
m.Remote = v.(string)
}
if v := ctx.Value("scheme"); v != nil {
m.Scheme = v.(string)
}
if v := ctx.Value("local"); v != nil {
m.Local = v.(string)
}
return m
}
// String implements Stringer interface
func (m Metadata) String() string {
s, err := json.Marshal(m)
if err == nil {
return string(s)
}
return err.Error()
}
// types for the requests/response types between signer and UI
type (
// SignTxRequest contains info about a Transaction to sign
SignTxRequest struct {
Transaction SendTxArgs `json:"transaction"`
Callinfo []ValidationInfo `json:"call_info"`
Meta Metadata `json:"meta"`
}
// SignTxResponse result from SignTxRequest
SignTxResponse struct {
//The UI may make changes to the TX
Transaction SendTxArgs `json:"transaction"`
Approved bool `json:"approved"`
Password string `json:"password"`
}
// ExportRequest info about query to export accounts
ExportRequest struct {
Address common.Address `json:"address"`
Meta Metadata `json:"meta"`
}
// ExportResponse response to export-request
ExportResponse struct {
Approved bool `json:"approved"`
}
// ImportRequest info about request to import an Account
ImportRequest struct {
Meta Metadata `json:"meta"`
}
ImportResponse struct {
Approved bool `json:"approved"`
OldPassword string `json:"old_password"`
NewPassword string `json:"new_password"`
}
SignDataRequest struct {
Address common.MixedcaseAddress `json:"address"`
Rawdata hexutil.Bytes `json:"raw_data"`
Message string `json:"message"`
Hash hexutil.Bytes `json:"hash"`
Meta Metadata `json:"meta"`
}
SignDataResponse struct {
Approved bool `json:"approved"`
Password string
}
NewAccountRequest struct {
Meta Metadata `json:"meta"`
}
NewAccountResponse struct {
Approved bool `json:"approved"`
Password string `json:"password"`
}
ListRequest struct {
Accounts []Account `json:"accounts"`
Meta Metadata `json:"meta"`
}
ListResponse struct {
Accounts []Account `json:"accounts"`
}
Message struct {
Text string `json:"text"`
}
StartupInfo struct {
Info map[string]interface{} `json:"info"`
}
)
var ErrRequestDenied = errors.New("Request denied")
// NewSignerAPI creates a new API that can be used for Account management.
// ksLocation specifies the directory where to store the password protected private
// key that is generated when a new Account is created.
// noUSB disables USB support that is required to support hardware devices such as
// ledger and trezor.
func NewSignerAPI(chainID int64, ksLocation string, noUSB bool, ui SignerUI, abidb *AbiDb, lightKDF bool) *SignerAPI {
var (
backends []accounts.Backend
n, p = keystore.StandardScryptN, keystore.StandardScryptP
)
if lightKDF {
n, p = keystore.LightScryptN, keystore.LightScryptP
}
// support password based accounts
if len(ksLocation) > 0 {
backends = append(backends, keystore.NewKeyStore(ksLocation, n, p))
}
if !noUSB {
// Start a USB hub for Ledger hardware wallets
if ledgerhub, err := usbwallet.NewLedgerHub(); err != nil {
log.Warn(fmt.Sprintf("Failed to start Ledger hub, disabling: %v", err))
} else {
backends = append(backends, ledgerhub)
log.Debug("Ledger support enabled")
}
// Start a USB hub for Trezor hardware wallets
if trezorhub, err := usbwallet.NewTrezorHub(); err != nil {
log.Warn(fmt.Sprintf("Failed to start Trezor hub, disabling: %v", err))
} else {
backends = append(backends, trezorhub)
log.Debug("Trezor support enabled")
}
}
return &SignerAPI{big.NewInt(chainID), accounts.NewManager(backends...), ui, NewValidator(abidb)}
}
// List returns the set of wallet this signer manages. Each wallet can contain
// multiple accounts.
func (api *SignerAPI) List(ctx context.Context) (Accounts, error) {
var accs []Account
for _, wallet := range api.am.Wallets() {
for _, acc := range wallet.Accounts() {
acc := Account{Typ: "Account", URL: wallet.URL(), Address: acc.Address}
accs = append(accs, acc)
}
}
result, err := api.UI.ApproveListing(&ListRequest{Accounts: accs, Meta: MetadataFromContext(ctx)})
if err != nil {
return nil, err
}
if result.Accounts == nil {
return nil, ErrRequestDenied
}
return result.Accounts, nil
}
// New creates a new password protected Account. The private key is protected with
// the given password. Users are responsible to backup the private key that is stored
// in the keystore location thas was specified when this API was created.
func (api *SignerAPI) New(ctx context.Context) (accounts.Account, error) {
be := api.am.Backends(keystore.KeyStoreType)
if len(be) == 0 {
return accounts.Account{}, errors.New("password based accounts not supported")
}
resp, err := api.UI.ApproveNewAccount(&NewAccountRequest{MetadataFromContext(ctx)})
if err != nil {
return accounts.Account{}, err
}
if !resp.Approved {
return accounts.Account{}, ErrRequestDenied
}
return be[0].(*keystore.KeyStore).NewAccount(resp.Password)
}
// logDiff logs the difference between the incoming (original) transaction and the one returned from the signer.
// it also returns 'true' if the transaction was modified, to make it possible to configure the signer not to allow
// UI-modifications to requests
func logDiff(original *SignTxRequest, new *SignTxResponse) bool {
modified := false
if f0, f1 := original.Transaction.From, new.Transaction.From; !reflect.DeepEqual(f0, f1) {
log.Info("Sender-account changed by UI", "was", f0, "is", f1)
modified = true
}
if t0, t1 := original.Transaction.To, new.Transaction.To; !reflect.DeepEqual(t0, t1) {
log.Info("Recipient-account changed by UI", "was", t0, "is", t1)
modified = true
}
if g0, g1 := original.Transaction.Gas, new.Transaction.Gas; g0 != g1 {
modified = true
log.Info("Gas changed by UI", "was", g0, "is", g1)
}
if g0, g1 := big.Int(original.Transaction.GasPrice), big.Int(new.Transaction.GasPrice); g0.Cmp(&g1) != 0 {
modified = true
log.Info("GasPrice changed by UI", "was", g0, "is", g1)
}
if v0, v1 := big.Int(original.Transaction.Value), big.Int(new.Transaction.Value); v0.Cmp(&v1) != 0 {
modified = true
log.Info("Value changed by UI", "was", v0, "is", v1)
}
if d0, d1 := original.Transaction.Data, new.Transaction.Data; d0 != d1 {
d0s := ""
d1s := ""
if d0 != nil {
d0s = common.ToHex(*d0)
}
if d1 != nil {
d1s = common.ToHex(*d1)
}
if d1s != d0s {
modified = true
log.Info("Data changed by UI", "was", d0s, "is", d1s)
}
}
if n0, n1 := original.Transaction.Nonce, new.Transaction.Nonce; n0 != n1 {
modified = true
log.Info("Nonce changed by UI", "was", n0, "is", n1)
}
return modified
}
// SignTransaction signs the given Transaction and returns it both as json and rlp-encoded form
func (api *SignerAPI) SignTransaction(ctx context.Context, args SendTxArgs, methodSelector *string) (*ethapi.SignTransactionResult, error) {
var (
err error
result SignTxResponse
)
msgs, err := api.validator.ValidateTransaction(&args, methodSelector)
if err != nil {
return nil, err
}
req := SignTxRequest{
Transaction: args,
Meta: MetadataFromContext(ctx),
Callinfo: msgs.Messages,
}
// Process approval
result, err = api.UI.ApproveTx(&req)
if err != nil {
return nil, err
}
if !result.Approved {
return nil, ErrRequestDenied
}
// Log changes made by the UI to the signing-request
logDiff(&req, &result)
var (
acc accounts.Account
wallet accounts.Wallet
)
acc = accounts.Account{Address: result.Transaction.From.Address()}
wallet, err = api.am.Find(acc)
if err != nil {
return nil, err
}
// Convert fields into a real transaction
var unsignedTx = result.Transaction.toTransaction()
// The one to sign is the one that was returned from the UI
signedTx, err := wallet.SignTxWithPassphrase(acc, result.Password, unsignedTx, api.chainID)
if err != nil {
api.UI.ShowError(err.Error())
return nil, err
}
rlpdata, err := rlp.EncodeToBytes(signedTx)
response := ethapi.SignTransactionResult{Raw: rlpdata, Tx: signedTx}
// Finally, send the signed tx to the UI
api.UI.OnApprovedTx(response)
// ...and to the external caller
return &response, nil
}
// Sign calculates an Ethereum ECDSA signature for:
// keccack256("\x19Ethereum Signed Message:\n" + len(message) + message))
//
// Note, the produced signature conforms to the secp256k1 curve R, S and V values,
// where the V value will be 27 or 28 for legacy reasons.
//
// The key used to calculate the signature is decrypted with the given password.
//
// https://github.com/ethereum/go-ethereum/wiki/Management-APIs#personal_sign
func (api *SignerAPI) Sign(ctx context.Context, addr common.MixedcaseAddress, data hexutil.Bytes) (hexutil.Bytes, error) {
sighash, msg := SignHash(data)
// We make the request prior to looking up if we actually have the account, to prevent
// account-enumeration via the API
req := &SignDataRequest{Address: addr, Rawdata: data, Message: msg, Hash: sighash, Meta: MetadataFromContext(ctx)}
res, err := api.UI.ApproveSignData(req)
if err != nil {
return nil, err
}
if !res.Approved {
return nil, ErrRequestDenied
}
// Look up the wallet containing the requested signer
account := accounts.Account{Address: addr.Address()}
wallet, err := api.am.Find(account)
if err != nil {
return nil, err
}
// Assemble sign the data with the wallet
signature, err := wallet.SignHashWithPassphrase(account, res.Password, sighash)
if err != nil {
api.UI.ShowError(err.Error())
return nil, err
}
signature[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
return signature, nil
}
// EcRecover returns the address for the Account that was used to create the signature.
// Note, this function is compatible with eth_sign and personal_sign. As such it recovers
// the address of:
// hash = keccak256("\x19Ethereum Signed Message:\n"${message length}${message})
// addr = ecrecover(hash, signature)
//
// Note, the signature must conform to the secp256k1 curve R, S and V values, where
// the V value must be be 27 or 28 for legacy reasons.
//
// https://github.com/ethereum/go-ethereum/wiki/Management-APIs#personal_ecRecover
func (api *SignerAPI) EcRecover(ctx context.Context, data, sig hexutil.Bytes) (common.Address, error) {
if len(sig) != 65 {
return common.Address{}, fmt.Errorf("signature must be 65 bytes long")
}
if sig[64] != 27 && sig[64] != 28 {
return common.Address{}, fmt.Errorf("invalid Ethereum signature (V is not 27 or 28)")
}
sig[64] -= 27 // Transform yellow paper V from 27/28 to 0/1
hash, _ := SignHash(data)
rpk, err := crypto.SigToPub(hash, sig)
if err != nil {
return common.Address{}, err
}
return crypto.PubkeyToAddress(*rpk), nil
}
// SignHash is a helper function that calculates a hash for the given message that can be
// safely used to calculate a signature from.
//
// The hash is calculated as
// keccak256("\x19Ethereum Signed Message:\n"${message length}${message}).
//
// This gives context to the signed message and prevents signing of transactions.
func SignHash(data []byte) ([]byte, string) {
msg := fmt.Sprintf("\x19Ethereum Signed Message:\n%d%s", len(data), data)
return crypto.Keccak256([]byte(msg)), msg
}
// Export returns encrypted private key associated with the given address in web3 keystore format.
func (api *SignerAPI) Export(ctx context.Context, addr common.Address) (json.RawMessage, error) {
res, err := api.UI.ApproveExport(&ExportRequest{Address: addr, Meta: MetadataFromContext(ctx)})
if err != nil {
return nil, err
}
if !res.Approved {
return nil, ErrRequestDenied
}
// Look up the wallet containing the requested signer
wallet, err := api.am.Find(accounts.Account{Address: addr})
if err != nil {
return nil, err
}
if wallet.URL().Scheme != keystore.KeyStoreScheme {
return nil, fmt.Errorf("Account is not a keystore-account")
}
return ioutil.ReadFile(wallet.URL().Path)
}
// Import tries to import the given keyJSON in the local keystore. The keyJSON data is expected to be
// in web3 keystore format. It will decrypt the keyJSON with the given passphrase and on successful
// decryption it will encrypt the key with the given newPassphrase and store it in the keystore.
func (api *SignerAPI) Import(ctx context.Context, keyJSON json.RawMessage) (Account, error) {
be := api.am.Backends(keystore.KeyStoreType)
if len(be) == 0 {
return Account{}, errors.New("password based accounts not supported")
}
res, err := api.UI.ApproveImport(&ImportRequest{Meta: MetadataFromContext(ctx)})
if err != nil {
return Account{}, err
}
if !res.Approved {
return Account{}, ErrRequestDenied
}
acc, err := be[0].(*keystore.KeyStore).Import(keyJSON, res.OldPassword, res.NewPassword)
if err != nil {
api.UI.ShowError(err.Error())
return Account{}, err
}
return Account{Typ: "Account", URL: acc.URL, Address: acc.Address}, nil
}
