// Copyright 2017 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/>.
// This file contains the implementation for interacting with the Ledger hardware
// wallets. The wire protocol spec can be found in the Ledger Blue GitHub repo:
// https://raw.githubusercontent.com/LedgerHQ/blue-app-eth/master/doc/ethapp.asc
package usbwallet
import (
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
"io"
"math/big"
"github.com/ethereum/go-ethereum/accounts"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
)
// ledgerOpcode is an enumeration encoding the supported Ledger opcodes.
type ledgerOpcode byte
// ledgerParam1 is an enumeration encoding the supported Ledger parameters for
// specific opcodes. The same parameter values may be reused between opcodes.
type ledgerParam1 byte
// ledgerParam2 is an enumeration encoding the supported Ledger parameters for
// specific opcodes. The same parameter values may be reused between opcodes.
type ledgerParam2 byte
const (
ledgerOpRetrieveAddress ledgerOpcode = 0x02 // Returns the public key and Ethereum address for a given BIP 32 path
ledgerOpSignTransaction ledgerOpcode = 0x04 // Signs an Ethereum transaction after having the user validate the parameters
ledgerOpGetConfiguration ledgerOpcode = 0x06 // Returns specific wallet application configuration
ledgerP1DirectlyFetchAddress ledgerParam1 = 0x00 // Return address directly from the wallet
ledgerP1InitTransactionData ledgerParam1 = 0x00 // First transaction data block for signing
ledgerP1ContTransactionData ledgerParam1 = 0x80 // Subsequent transaction data block for signing
ledgerP2DiscardAddressChainCode ledgerParam2 = 0x00 // Do not return the chain code along with the address
)
// errLedgerReplyInvalidHeader is the error message returned by a Ledger data exchange
// if the device replies with a mismatching header. This usually means the device
// is in browser mode.
var errLedgerReplyInvalidHeader = errors.New("ledger: invalid reply header")
// errLedgerInvalidVersionReply is the error message returned by a Ledger version retrieval
// when a response does arrive, but it does not contain the expected data.
var errLedgerInvalidVersionReply = errors.New("ledger: invalid version reply")
// ledgerDriver implements the communication with a Ledger hardware wallet.
type ledgerDriver struct {
device io.ReadWriter // USB device connection to communicate through
version [3]byte // Current version of the Ledger firmware (zero if app is offline)
browser bool // Flag whether the Ledger is in browser mode (reply channel mismatch)
failure error // Any failure that would make the device unusable
log log.Logger // Contextual logger to tag the ledger with its id
}
// newLedgerDriver creates a new instance of a Ledger USB protocol driver.
func newLedgerDriver(logger log.Logger) driver {
return &ledgerDriver{
log: logger,
}
}
// Status implements usbwallet.driver, returning various states the Ledger can
// currently be in.
func (w *ledgerDriver) Status() (string, error) {
if w.failure != nil {
return fmt.Sprintf("Failed: %v", w.failure), w.failure
}
if w.browser {
return "Ethereum app in browser mode", w.failure
}
if w.offline() {
return "Ethereum app offline", w.failure
}
return fmt.Sprintf("Ethereum app v%d.%d.%d online", w.version[0], w.version[1], w.version[2]), w.failure
}
// offline returns whether the wallet and the Ethereum app is offline or not.
//
// The method assumes that the state lock is held!
func (w *ledgerDriver) offline() bool {
return w.version == [3]byte{0, 0, 0}
}
// Open implements usbwallet.driver, attempting to initialize the connection to the
// Ledger hardware wallet. The Ledger does not require a user passphrase, so that
// parameter is silently discarded.
func (w *ledgerDriver) Open(device io.ReadWriter, passphrase string) error {
w.device, w.failure = device, nil
_, err := w.ledgerDerive(accounts.DefaultBaseDerivationPath)
if err != nil {
// Ethereum app is not running or in browser mode, nothing more to do, return
if err == errLedgerReplyInvalidHeader {
w.browser = true
}
return nil
}
// Try to resolve the Ethereum app's version, will fail prior to v1.0.2
if w.version, err = w.ledgerVersion(); err != nil {
w.version = [3]byte{1, 0, 0} // Assume worst case, can't verify if v1.0.0 or v1.0.1
}
return nil
}
// Close implements usbwallet.driver, cleaning up and metadata maintained within
// the Ledger driver.
func (w *ledgerDriver) Close() error {
w.browser, w.version = false, [3]byte{}
return nil
}
// Heartbeat implements usbwallet.driver, performing a sanity check against the
// Ledger to see if it's still online.
func (w *ledgerDriver) Heartbeat() error {
if _, err := w.ledgerVersion(); err != nil && err != errLedgerInvalidVersionReply {
w.failure = err
return err
}
return nil
}
// Derive implements usbwallet.driver, sending a derivation request to the Ledger
// and returning the Ethereum address located on that derivation path.
func (w *ledgerDriver) Derive(path accounts.DerivationPath) (common.Address, error) {
return w.ledgerDerive(path)
}
// SignTx implements usbwallet.driver, sending the transaction to the Ledger and
// waiting for the user to confirm or deny the transaction.
//
// Note, if the version of the Ethereum application running on the Ledger wallet is
// too old to sign EIP-155 transactions, but such is requested nonetheless, an error
// will be returned opposed to silently signing in Homestead mode.
func (w *ledgerDriver) SignTx(path accounts.DerivationPath, tx *types.Transaction, chainID *big.Int) (common.Address, *types.Transaction, error) {
// If the Ethereum app doesn't run, abort
if w.offline() {
return common.Address{}, nil, accounts.ErrWalletClosed
}
// Ensure the wallet is capable of signing the given transaction
if chainID != nil && w.version[0] <= 1 && w.version[1] <= 0 && w.version[2] <= 2 {
return common.Address{}, nil, fmt.Errorf("Ledger v%d.%d.%d doesn't support signing this transaction, please update to v1.0.3 at least", w.version[0], w.version[1], w.version[2])
}
// All infos gathered and metadata checks out, request signing
return w.ledgerSign(path, tx, chainID)
}
// ledgerVersion retrieves the current version of the Ethereum wallet app running
// on the Ledger wallet.
//
// The version retrieval protocol is defined as follows:
//
// CLA | INS | P1 | P2 | Lc | Le
// ----+-----+----+----+----+---
// E0 | 06 | 00 | 00 | 00 | 04
//
// With no input data, and the output data being:
//
// Description | Length
// ---------------------------------------------------+--------
// Flags 01: arbitrary data signature enabled by user | 1 byte
// Application major version | 1 byte
// Application minor version | 1 byte
// Application patch version | 1 byte
func (w *ledgerDriver) ledgerVersion() ([3]byte, error) {
// Send the request and wait for the response
reply, err := w.ledgerExchange(ledgerOpGetConfiguration, 0, 0, nil)
if err != nil {
return [3]byte{}, err
}
if len(reply) != 4 {
return [3]byte{}, errLedgerInvalidVersionReply
}
// Cache the version for future reference
var version [3]byte
copy(version[:], reply[1:])
return version, nil
}
// ledgerDerive retrieves the currently active Ethereum address from a Ledger
// wallet at the specified derivation path.
//
// The address derivation protocol is defined as follows:
//
// CLA | INS | P1 | P2 | Lc | Le
// ----+-----+----+----+-----+---
// E0 | 02 | 00 return address
// 01 display address and confirm before returning
// | 00: do not return the chain code
// | 01: return the chain code
// | var | 00
//
// Where the input data is:
//
// Description | Length
// -------------------------------------------------+--------
// Number of BIP 32 derivations to perform (max 10) | 1 byte
// First derivation index (big endian) | 4 bytes
// ... | 4 bytes
// Last derivation index (big endian) | 4 bytes
//
// And the output data is:
//
// Description | Length
// ------------------------+-------------------
// Public Key length | 1 byte
// Uncompressed Public Key | arbitrary
// Ethereum address length | 1 byte
// Ethereum address | 40 bytes hex ascii
// Chain code if requested | 32 bytes
func (w *ledgerDriver) ledgerDerive(derivationPath []uint32) (common.Address, error) {
// Flatten the derivation path into the Ledger request
path := make([]byte, 1+4*len(derivationPath))
path[0] = byte(len(derivationPath))
for i, component := range derivationPath {
binary.BigEndian.PutUint32(path[1+4*i:], component)
}
// Send the request and wait for the response
reply, err := w.ledgerExchange(ledgerOpRetrieveAddress, ledgerP1DirectlyFetchAddress, ledgerP2DiscardAddressChainCode, path)
if err != nil {
return common.Address{}, err
}
// Discard the public key, we don't need that for now
if len(reply) < 1 || len(reply) < 1+int(reply[0]) {
return common.Address{}, errors.New("reply lacks public key entry")
}
reply = reply[1+int(reply[0]):]
// Extract the Ethereum hex address string
if len(reply) < 1 || len(reply) < 1+int(reply[0]) {
return common.Address{}, errors.New("reply lacks address entry")
}
hexstr := reply[1 : 1+int(reply[0])]
// Decode the hex sting into an Ethereum address and return
var address common.Address
if _, err = hex.Decode(address[:], hexstr); err != nil {
return common.Address{}, err
}
return address, nil
}
// ledgerSign sends the transaction to the Ledger wallet, and waits for the user
// to confirm or deny the transaction.
//
// The transaction signing protocol is defined as follows:
//
// CLA | INS | P1 | P2 | Lc | Le
// ----+-----+----+----+-----+---
// E0 | 04 | 00: first transaction data block
// 80: subsequent transaction data block
// | 00 | variable | variable
//
// Where the input for the first transaction block (first 255 bytes) is:
//
// Description | Length
// -------------------------------------------------+----------
// Number of BIP 32 derivations to perform (max 10) | 1 byte
// First derivation index (big endian) | 4 bytes
// ... | 4 bytes
// Last derivation index (big endian) | 4 bytes
// RLP transaction chunk | arbitrary
//
// And the input for subsequent transaction blocks (first 255 bytes) are:
//
// Description | Length
// ----------------------+----------
// RLP transaction chunk | arbitrary
//
// And the output data is:
//
// Description | Length
// ------------+---------
// signature V | 1 byte
// signature R | 32 bytes
// signature S | 32 bytes
func (w *ledgerDriver) ledgerSign(derivationPath []uint32, tx *types.Transaction, chainID *big.Int) (common.Address, *types.Transaction, error) {
// Flatten the derivation path into the Ledger request
path := make([]byte, 1+4*len(derivationPath))
path[0] = byte(len(derivationPath))
for i, component := range derivationPath {
binary.BigEndian.PutUint32(path[1+4*i:], component)
}
// Create the transaction RLP based on whether legacy or EIP155 signing was requested
var (
txrlp []byte
err error
)
if chainID == nil {
if txrlp, err = rlp.EncodeToBytes([]interface{}{tx.Nonce(), tx.GasPrice(), tx.Gas(), tx.To(), tx.Value(), tx.Data()}); err != nil {
return common.Address{}, nil, err
}
} else {
if txrlp, err = rlp.EncodeToBytes([]interface{}{tx.Nonce(), tx.GasPrice(), tx.Gas(), tx.To(), tx.Value(), tx.Data(), chainID, big.NewInt(0), big.NewInt(0)}); err != nil {
return common.Address{}, nil, err
}
}
payload := append(path, txrlp...)
// Send the request and wait for the response
var (
op = ledgerP1InitTransactionData
reply []byte
)
for len(payload) > 0 {
// Calculate the size of the next data chunk
chunk := 255
if chunk > len(payload) {
chunk = len(payload)
}
// Send the chunk over, ensuring it's processed correctly
reply, err = w.ledgerExchange(ledgerOpSignTransaction, op, 0, payload[:chunk])
if err != nil {
return common.Address{}, nil, err
}
// Shift the payload and ensure subsequent chunks are marked as such
payload = payload[chunk:]
op = ledgerP1ContTransactionData
}
// Extract the Ethereum signature and do a sanity validation
if len(reply) != 65 {
return common.Address{}, nil, errors.New("reply lacks signature")
}
signature := append(reply[1:], reply[0])
// Create the correct signer and signature transform based on the chain ID
var signer types.Signer
if chainID == nil {
signer = new(types.HomesteadSigner)
} else {
signer = types.NewEIP155Signer(chainID)
signature[64] -= byte(chainID.Uint64()*2 + 35)
}
signed, err := tx.WithSignature(signer, signature)
if err != nil {
return common.Address{}, nil, err
}
sender, err := types.Sender(signer, signed)
if err != nil {
return common.Address{}, nil, err
}
return sender, signed, nil
}
// ledgerExchange performs a data exchange with the Ledger wallet, sending it a
// message and retrieving the response.
//
// The common transport header is defined as follows:
//
// Description | Length
// --------------------------------------+----------
// Communication channel ID (big endian) | 2 bytes
// Command tag | 1 byte
// Packet sequence index (big endian) | 2 bytes
// Payload | arbitrary
//
// The Communication channel ID allows commands multiplexing over the same
// physical link. It is not used for the time being, and should be set to 0101
// to avoid compatibility issues with implementations ignoring a leading 00 byte.
//
// The Command tag describes the message content. Use TAG_APDU (0x05) for standard
// APDU payloads, or TAG_PING (0x02) for a simple link test.
//
// The Packet sequence index describes the current sequence for fragmented payloads.
// The first fragment index is 0x00.
//
// APDU Command payloads are encoded as follows:
//
// Description | Length
// -----------------------------------
// APDU length (big endian) | 2 bytes
// APDU CLA | 1 byte
// APDU INS | 1 byte
// APDU P1 | 1 byte
// APDU P2 | 1 byte
// APDU length | 1 byte
// Optional APDU data | arbitrary
func (w *ledgerDriver) ledgerExchange(opcode ledgerOpcode, p1 ledgerParam1, p2 ledgerParam2, data []byte) ([]byte, error) {
// Construct the message payload, possibly split into multiple chunks
apdu := make([]byte, 2, 7+len(data))
binary.BigEndian.PutUint16(apdu, uint16(5+len(data)))
apdu = append(apdu, []byte{0xe0, byte(opcode), byte(p1), byte(p2), byte(len(data))}...)
apdu = append(apdu, data...)
// Stream all the chunks to the device
header := []byte{0x01, 0x01, 0x05, 0x00, 0x00} // Channel ID and command tag appended
chunk := make([]byte, 64)
space := len(chunk) - len(header)
for i := 0; len(apdu) > 0; i++ {
// Construct the new message to stream
chunk = append(chunk[:0], header...)
binary.BigEndian.PutUint16(chunk[3:], uint16(i))
if len(apdu) > space {
chunk = append(chunk, apdu[:space]...)
apdu = apdu[space:]
} else {
chunk = append(chunk, apdu...)
apdu = nil
}
// Send over to the device
w.log.Trace("Data chunk sent to the Ledger", "chunk", hexutil.Bytes(chunk))
if _, err := w.device.Write(chunk); err != nil {
return nil, err
}
}
// Stream the reply back from the wallet in 64 byte chunks
var reply []byte
chunk = chunk[:64] // Yeah, we surely have enough space
for {
// Read the next chunk from the Ledger wallet
if _, err := io.ReadFull(w.device, chunk); err != nil {
return nil, err
}
w.log.Trace("Data chunk received from the Ledger", "chunk", hexutil.Bytes(chunk))
// Make sure the transport header matches
if chunk[0] != 0x01 || chunk[1] != 0x01 || chunk[2] != 0x05 {
return nil, errLedgerReplyInvalidHeader
}
// If it's the first chunk, retrieve the total message length
var payload []byte
if chunk[3] == 0x00 && chunk[4] == 0x00 {
reply = make([]byte, 0, int(binary.BigEndian.Uint16(chunk[5:7])))
payload = chunk[7:]
} else {
payload = chunk[5:]
}
// Append to the reply and stop when filled up
if left := cap(reply) - len(reply); left > len(payload) {
reply = append(reply, payload...)
} else {
reply = append(reply, payload[:left]...)
break
}
}
return reply[:len(reply)-2], nil
}
