diff options
Diffstat (limited to 'accounts/scwallet')
| -rw-r--r-- | accounts/scwallet/README.md | 102 | ||||
| -rw-r--r-- | accounts/scwallet/apdu.go | 87 | ||||
| -rw-r--r-- | accounts/scwallet/hub.go | 302 | ||||
| -rw-r--r-- | accounts/scwallet/securechannel.go | 346 | ||||
| -rw-r--r-- | accounts/scwallet/wallet.go | 1082 |
5 files changed, 1919 insertions, 0 deletions
diff --git a/accounts/scwallet/README.md b/accounts/scwallet/README.md new file mode 100644 index 0000000..cfca916 --- /dev/null +++ b/accounts/scwallet/README.md @@ -0,0 +1,102 @@ +# Using the smartcard wallet + +## Requirements + + * A USB smartcard reader + * A keycard that supports the status app + * PCSCD version 4.3 running on your system **Only version 4.3 is currently supported** + +## Preparing the smartcard + + **WARNING: FOILLOWING THESE INSTRUCTIONS WILL DESTROY THE MASTER KEY ON YOUR CARD. ONLY PROCEED IF NO FUNDS ARE ASSOCIATED WITH THESE ACCOUNTS** + + You can use status' [keycard-cli](https://github.com/status-im/keycard-cli) and you should get _at least_ version 2.1.1 of their [smartcard application](https://github.com/status-im/status-keycard/releases/download/2.2.1/keycard_v2.2.1.cap) + + You also need to make sure that the PCSC daemon is running on your system. + + Then, you can install the application to the card by typing: + + ``` + keycard install -a keycard_v2.2.1.cap && keycard init + ``` + + At the end of this process, you will be provided with a PIN, a PUK and a pairing password. Write them down, you'll need them shortly. + + Start `geth` with the `console` command. You will notice the following warning: + + ``` + WARN [04-09|16:58:38.898] Failed to open wallet url=keycard://044def09 err="smartcard: pairing password needed" + ``` + + Write down the URL (`keycard://044def09` in this example). Then ask `geth` to open the wallet: + + ``` + > personal.openWallet("keycard://044def09") + Please enter the pairing password: + ``` + + Enter the pairing password that you have received during card initialization. Same with the PIN that you will subsequently be + asked for. + + If everything goes well, you should see your new account when typing `personal` on the console: + + ``` + > personal + WARN [04-09|17:02:07.330] Smartcard wallet account derivation failed url=keycard://044def09 err="Unexpected response status Cla=0x80, Ins=0xd1, Sw=0x6985" + { + listAccounts: [], + listWallets: [{ + status: "Empty, waiting for initialization", + url: "keycard://044def09" + }], + ... + } + ``` + + So the communication with the card is working, but there is no key associated with this wallet. Let's create it: + + ``` + > personal.initializeWallet("keycard://044def09") + "tilt ... impact" + ``` + + You should get a list of words, this is your seed so write them down. Your wallet should now be initialized: + + ``` + > personal.listWallets + [{ + accounts: [{ + address: "0x678b7cd55c61917defb23546a41803c5bfefbc7a", + url: "keycard://044d/m/44'/60'/0'/0/0" + }], + status: "Online", + url: "keycard://044def09" + }] + ``` + + You're all set! + +## Usage + + 1. Start `geth` with the `console` command + 2. Check the card's URL by checking `personal.listWallets`: + +``` + listWallets: [{ + status: "Online, can derive public keys", + url: "keycard://a4d73015" + }] +``` + + 3. Open the wallet, you will be prompted for your pairing password, then PIN: + +``` +personal.openWallet("keycard://a4d73015") +``` + + 4. Check that creation was successful by typing e.g. `personal`. Then use it like a regular wallet. + +## Known issues + + * Starting geth with a valid card seems to make firefox crash. + * PCSC version 4.4 should work, but is currently untested diff --git a/accounts/scwallet/apdu.go b/accounts/scwallet/apdu.go new file mode 100644 index 0000000..bd36606 --- /dev/null +++ b/accounts/scwallet/apdu.go @@ -0,0 +1,87 @@ +// Copyright 2018 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 scwallet + +import ( + "bytes" + "encoding/binary" + "fmt" +) + +// commandAPDU represents an application data unit sent to a smartcard. +type commandAPDU struct { + Cla, Ins, P1, P2 uint8 // Class, Instruction, Parameter 1, Parameter 2 + Data []byte // Command data + Le uint8 // Command data length +} + +// serialize serializes a command APDU. +func (ca commandAPDU) serialize() ([]byte, error) { + buf := new(bytes.Buffer) + + if err := binary.Write(buf, binary.BigEndian, ca.Cla); err != nil { + return nil, err + } + if err := binary.Write(buf, binary.BigEndian, ca.Ins); err != nil { + return nil, err + } + if err := binary.Write(buf, binary.BigEndian, ca.P1); err != nil { + return nil, err + } + if err := binary.Write(buf, binary.BigEndian, ca.P2); err != nil { + return nil, err + } + if len(ca.Data) > 0 { + if err := binary.Write(buf, binary.BigEndian, uint8(len(ca.Data))); err != nil { + return nil, err + } + if err := binary.Write(buf, binary.BigEndian, ca.Data); err != nil { + return nil, err + } + } + if err := binary.Write(buf, binary.BigEndian, ca.Le); err != nil { + return nil, err + } + return buf.Bytes(), nil +} + +// responseAPDU represents an application data unit received from a smart card. +type responseAPDU struct { + Data []byte // response data + Sw1, Sw2 uint8 // status words 1 and 2 +} + +// deserialize deserializes a response APDU. +func (ra *responseAPDU) deserialize(data []byte) error { + if len(data) < 2 { + return fmt.Errorf("can not deserialize data: payload too short (%d < 2)", len(data)) + } + + ra.Data = make([]byte, len(data)-2) + + buf := bytes.NewReader(data) + if err := binary.Read(buf, binary.BigEndian, &ra.Data); err != nil { + return err + } + if err := binary.Read(buf, binary.BigEndian, &ra.Sw1); err != nil { + return err + } + if err := binary.Read(buf, binary.BigEndian, &ra.Sw2); err != nil { + return err + } + return nil +} diff --git a/accounts/scwallet/hub.go b/accounts/scwallet/hub.go new file mode 100644 index 0000000..ceb422c --- /dev/null +++ b/accounts/scwallet/hub.go @@ -0,0 +1,302 @@ +// Copyright 2018 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 package implements support for smartcard-based hardware wallets such as +// the one written by Status: https://github.com/status-im/hardware-wallet +// +// This implementation of smartcard wallets have a different interaction process +// to other types of hardware wallet. The process works like this: +// +// 1. (First use with a given client) Establish a pairing between hardware +// wallet and client. This requires a secret value called a 'pairing password'. +// You can pair with an unpaired wallet with `personal.openWallet(URI, pairing password)`. +// 2. (First use only) Initialize the wallet, which generates a keypair, stores +// it on the wallet, and returns it so the user can back it up. You can +// initialize a wallet with `personal.initializeWallet(URI)`. +// 3. Connect to the wallet using the pairing information established in step 1. +// You can connect to a paired wallet with `personal.openWallet(URI, PIN)`. +// 4. Interact with the wallet as normal. + +package scwallet + +import ( + "encoding/json" + "io/ioutil" + "os" + "path/filepath" + "sort" + "sync" + "time" + + "github.com/ava-labs/coreth/accounts" + "github.com/ava-labs/go-ethereum/common" + "github.com/ava-labs/go-ethereum/event" + "github.com/ava-labs/go-ethereum/log" + pcsc "github.com/gballet/go-libpcsclite" +) + +// Scheme is the URI prefix for smartcard wallets. +const Scheme = "keycard" + +// refreshCycle is the maximum time between wallet refreshes (if USB hotplug +// notifications don't work). +const refreshCycle = time.Second + +// refreshThrottling is the minimum time between wallet refreshes to avoid thrashing. +const refreshThrottling = 500 * time.Millisecond + +// smartcardPairing contains information about a smart card we have paired with +// or might pair with the hub. +type smartcardPairing struct { + PublicKey []byte `json:"publicKey"` + PairingIndex uint8 `json:"pairingIndex"` + PairingKey []byte `json:"pairingKey"` + Accounts map[common.Address]accounts.DerivationPath `json:"accounts"` +} + +// Hub is a accounts.Backend that can find and handle generic PC/SC hardware wallets. +type Hub struct { + scheme string // Protocol scheme prefixing account and wallet URLs. + + context *pcsc.Client + datadir string + pairings map[string]smartcardPairing + + refreshed time.Time // Time instance when the list of wallets was last refreshed + wallets map[string]*Wallet // Mapping from reader names to wallet instances + updateFeed event.Feed // Event feed to notify wallet additions/removals + updateScope event.SubscriptionScope // Subscription scope tracking current live listeners + updating bool // Whether the event notification loop is running + + quit chan chan error + + stateLock sync.RWMutex // Protects the internals of the hub from racey access +} + +func (hub *Hub) readPairings() error { + hub.pairings = make(map[string]smartcardPairing) + pairingFile, err := os.Open(filepath.Join(hub.datadir, "smartcards.json")) + if err != nil { + if os.IsNotExist(err) { + return nil + } + return err + } + + pairingData, err := ioutil.ReadAll(pairingFile) + if err != nil { + return err + } + var pairings []smartcardPairing + if err := json.Unmarshal(pairingData, &pairings); err != nil { + return err + } + + for _, pairing := range pairings { + hub.pairings[string(pairing.PublicKey)] = pairing + } + return nil +} + +func (hub *Hub) writePairings() error { + pairingFile, err := os.OpenFile(filepath.Join(hub.datadir, "smartcards.json"), os.O_RDWR|os.O_CREATE, 0755) + if err != nil { + return err + } + defer pairingFile.Close() + + pairings := make([]smartcardPairing, 0, len(hub.pairings)) + for _, pairing := range hub.pairings { + pairings = append(pairings, pairing) + } + + pairingData, err := json.Marshal(pairings) + if err != nil { + return err + } + + if _, err := pairingFile.Write(pairingData); err != nil { + return err + } + + return nil +} + +func (hub *Hub) pairing(wallet *Wallet) *smartcardPairing { + if pairing, ok := hub.pairings[string(wallet.PublicKey)]; ok { + return &pairing + } + return nil +} + +func (hub *Hub) setPairing(wallet *Wallet, pairing *smartcardPairing) error { + if pairing == nil { + delete(hub.pairings, string(wallet.PublicKey)) + } else { + hub.pairings[string(wallet.PublicKey)] = *pairing + } + return hub.writePairings() +} + +// NewHub creates a new hardware wallet manager for smartcards. +func NewHub(daemonPath string, scheme string, datadir string) (*Hub, error) { + context, err := pcsc.EstablishContext(daemonPath, pcsc.ScopeSystem) + if err != nil { + return nil, err + } + hub := &Hub{ + scheme: scheme, + context: context, + datadir: datadir, + wallets: make(map[string]*Wallet), + quit: make(chan chan error), + } + if err := hub.readPairings(); err != nil { + return nil, err + } + hub.refreshWallets() + return hub, nil +} + +// Wallets implements accounts.Backend, returning all the currently tracked smart +// cards that appear to be hardware wallets. +func (hub *Hub) Wallets() []accounts.Wallet { + // Make sure the list of wallets is up to date + hub.refreshWallets() + + hub.stateLock.RLock() + defer hub.stateLock.RUnlock() + + cpy := make([]accounts.Wallet, 0, len(hub.wallets)) + for _, wallet := range hub.wallets { + cpy = append(cpy, wallet) + } + sort.Sort(accounts.WalletsByURL(cpy)) + return cpy +} + +// refreshWallets scans the devices attached to the machine and updates the +// list of wallets based on the found devices. +func (hub *Hub) refreshWallets() { + // Don't scan the USB like crazy it the user fetches wallets in a loop + hub.stateLock.RLock() + elapsed := time.Since(hub.refreshed) + hub.stateLock.RUnlock() + + if elapsed < refreshThrottling { + return + } + // Retrieve all the smart card reader to check for cards + readers, err := hub.context.ListReaders() + if err != nil { + // This is a perverted hack, the scard library returns an error if no card + // readers are present instead of simply returning an empty list. We don't + // want to fill the user's log with errors, so filter those out. + if err.Error() != "scard: Cannot find a smart card reader." { + log.Error("Failed to enumerate smart card readers", "err", err) + return + } + } + // Transform the current list of wallets into the new one + hub.stateLock.Lock() + + events := []accounts.WalletEvent{} + seen := make(map[string]struct{}) + + for _, reader := range readers { + // Mark the reader as present + seen[reader] = struct{}{} + + // If we alreay know about this card, skip to the next reader, otherwise clean up + if wallet, ok := hub.wallets[reader]; ok { + if err := wallet.ping(); err == nil { + continue + } + wallet.Close() + events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletDropped}) + delete(hub.wallets, reader) + } + // New card detected, try to connect to it + card, err := hub.context.Connect(reader, pcsc.ShareShared, pcsc.ProtocolAny) + if err != nil { + log.Debug("Failed to open smart card", "reader", reader, "err", err) + continue + } + wallet := NewWallet(hub, card) + if err = wallet.connect(); err != nil { + log.Debug("Failed to connect to smart card", "reader", reader, "err", err) + card.Disconnect(pcsc.LeaveCard) + continue + } + // Card connected, start tracking in amongs the wallets + hub.wallets[reader] = wallet + events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletArrived}) + } + // Remove any wallets no longer present + for reader, wallet := range hub.wallets { + if _, ok := seen[reader]; !ok { + wallet.Close() + events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletDropped}) + delete(hub.wallets, reader) + } + } + hub.refreshed = time.Now() + hub.stateLock.Unlock() + + for _, event := range events { + hub.updateFeed.Send(event) + } +} + +// Subscribe implements accounts.Backend, creating an async subscription to +// receive notifications on the addition or removal of smart card wallets. +func (hub *Hub) Subscribe(sink chan<- accounts.WalletEvent) event.Subscription { + // We need the mutex to reliably start/stop the update loop + hub.stateLock.Lock() + defer hub.stateLock.Unlock() + + // Subscribe the caller and track the subscriber count + sub := hub.updateScope.Track(hub.updateFeed.Subscribe(sink)) + + // Subscribers require an active notification loop, start it + if !hub.updating { + hub.updating = true + go hub.updater() + } + return sub +} + +// updater is responsible for maintaining an up-to-date list of wallets managed +// by the smart card hub, and for firing wallet addition/removal events. +func (hub *Hub) updater() { + for { + // TODO: Wait for a USB hotplug event (not supported yet) or a refresh timeout + // <-hub.changes + time.Sleep(refreshCycle) + + // Run the wallet refresher + hub.refreshWallets() + + // If all our subscribers left, stop the updater + hub.stateLock.Lock() + if hub.updateScope.Count() == 0 { + hub.updating = false + hub.stateLock.Unlock() + return + } + hub.stateLock.Unlock() + } +} diff --git a/accounts/scwallet/securechannel.go b/accounts/scwallet/securechannel.go new file mode 100644 index 0000000..c1b7cff --- /dev/null +++ b/accounts/scwallet/securechannel.go @@ -0,0 +1,346 @@ +// Copyright 2018 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 scwallet + +import ( + "bytes" + "crypto/aes" + "crypto/cipher" + "crypto/rand" + "crypto/sha256" + "crypto/sha512" + "fmt" + + "github.com/ava-labs/go-ethereum/crypto" + pcsc "github.com/gballet/go-libpcsclite" + "github.com/wsddn/go-ecdh" + "golang.org/x/crypto/pbkdf2" + "golang.org/x/text/unicode/norm" +) + +const ( + maxPayloadSize = 223 + pairP1FirstStep = 0 + pairP1LastStep = 1 + + scSecretLength = 32 + scBlockSize = 16 + + insOpenSecureChannel = 0x10 + insMutuallyAuthenticate = 0x11 + insPair = 0x12 + insUnpair = 0x13 + + pairingSalt = "Keycard Pairing Password Salt" +) + +// SecureChannelSession enables secure communication with a hardware wallet. +type SecureChannelSession struct { + card *pcsc.Card // A handle to the smartcard for communication + secret []byte // A shared secret generated from our ECDSA keys + publicKey []byte // Our own ephemeral public key + PairingKey []byte // A permanent shared secret for a pairing, if present + sessionEncKey []byte // The current session encryption key + sessionMacKey []byte // The current session MAC key + iv []byte // The current IV + PairingIndex uint8 // The pairing index +} + +// NewSecureChannelSession creates a new secure channel for the given card and public key. +func NewSecureChannelSession(card *pcsc.Card, keyData []byte) (*SecureChannelSession, error) { + // Generate an ECDSA keypair for ourselves + gen := ecdh.NewEllipticECDH(crypto.S256()) + private, public, err := gen.GenerateKey(rand.Reader) + if err != nil { + return nil, err + } + + cardPublic, ok := gen.Unmarshal(keyData) + if !ok { + return nil, fmt.Errorf("Could not unmarshal public key from card") + } + + secret, err := gen.GenerateSharedSecret(private, cardPublic) + if err != nil { + return nil, err + } + + return &SecureChannelSession{ + card: card, + secret: secret, + publicKey: gen.Marshal(public), + }, nil +} + +// Pair establishes a new pairing with the smartcard. +func (s *SecureChannelSession) Pair(pairingPassword []byte) error { + secretHash := pbkdf2.Key(norm.NFKD.Bytes(pairingPassword), norm.NFKD.Bytes([]byte(pairingSalt)), 50000, 32, sha256.New) + + challenge := make([]byte, 32) + if _, err := rand.Read(challenge); err != nil { + return err + } + + response, err := s.pair(pairP1FirstStep, challenge) + if err != nil { + return err + } + + md := sha256.New() + md.Write(secretHash[:]) + md.Write(challenge) + + expectedCryptogram := md.Sum(nil) + cardCryptogram := response.Data[:32] + cardChallenge := response.Data[32:64] + + if !bytes.Equal(expectedCryptogram, cardCryptogram) { + return fmt.Errorf("Invalid card cryptogram %v != %v", expectedCryptogram, cardCryptogram) + } + + md.Reset() + md.Write(secretHash[:]) + md.Write(cardChallenge) + response, err = s.pair(pairP1LastStep, md.Sum(nil)) + if err != nil { + return err + } + + md.Reset() + md.Write(secretHash[:]) + md.Write(response.Data[1:]) + s.PairingKey = md.Sum(nil) + s.PairingIndex = response.Data[0] + + return nil +} + +// Unpair disestablishes an existing pairing. +func (s *SecureChannelSession) Unpair() error { + if s.PairingKey == nil { + return fmt.Errorf("Cannot unpair: not paired") + } + + _, err := s.transmitEncrypted(claSCWallet, insUnpair, s.PairingIndex, 0, []byte{}) + if err != nil { + return err + } + s.PairingKey = nil + // Close channel + s.iv = nil + return nil +} + +// Open initializes the secure channel. +func (s *SecureChannelSession) Open() error { + if s.iv != nil { + return fmt.Errorf("Session already opened") + } + + response, err := s.open() + if err != nil { + return err + } + + // Generate the encryption/mac key by hashing our shared secret, + // pairing key, and the first bytes returned from the Open APDU. + md := sha512.New() + md.Write(s.secret) + md.Write(s.PairingKey) + md.Write(response.Data[:scSecretLength]) + keyData := md.Sum(nil) + s.sessionEncKey = keyData[:scSecretLength] + s.sessionMacKey = keyData[scSecretLength : scSecretLength*2] + + // The IV is the last bytes returned from the Open APDU. + s.iv = response.Data[scSecretLength:] + + return s.mutuallyAuthenticate() +} + +// mutuallyAuthenticate is an internal method to authenticate both ends of the +// connection. +func (s *SecureChannelSession) mutuallyAuthenticate() error { + data := make([]byte, scSecretLength) + if _, err := rand.Read(data); err != nil { + return err + } + + response, err := s.transmitEncrypted(claSCWallet, insMutuallyAuthenticate, 0, 0, data) + if err != nil { + return err + } + if response.Sw1 != 0x90 || response.Sw2 != 0x00 { + return fmt.Errorf("Got unexpected response from MUTUALLY_AUTHENTICATE: 0x%x%x", response.Sw1, response.Sw2) + } + + if len(response.Data) != scSecretLength { + return fmt.Errorf("Response from MUTUALLY_AUTHENTICATE was %d bytes, expected %d", len(response.Data), scSecretLength) + } + + return nil +} + +// open is an internal method that sends an open APDU. +func (s *SecureChannelSession) open() (*responseAPDU, error) { + return transmit(s.card, &commandAPDU{ + Cla: claSCWallet, + Ins: insOpenSecureChannel, + P1: s.PairingIndex, + P2: 0, + Data: s.publicKey, + Le: 0, + }) +} + +// pair is an internal method that sends a pair APDU. +func (s *SecureChannelSession) pair(p1 uint8, data []byte) (*responseAPDU, error) { + return transmit(s.card, &commandAPDU{ + Cla: claSCWallet, + Ins: insPair, + P1: p1, + P2: 0, + Data: data, + Le: 0, + }) +} + +// transmitEncrypted sends an encrypted message, and decrypts and returns the response. +func (s *SecureChannelSession) transmitEncrypted(cla, ins, p1, p2 byte, data []byte) (*responseAPDU, error) { + if s.iv == nil { + return nil, fmt.Errorf("Channel not open") + } + + data, err := s.encryptAPDU(data) + if err != nil { + return nil, err + } + meta := [16]byte{cla, ins, p1, p2, byte(len(data) + scBlockSize)} + if err = s.updateIV(meta[:], data); err != nil { + return nil, err + } + + fulldata := make([]byte, len(s.iv)+len(data)) + copy(fulldata, s.iv) + copy(fulldata[len(s.iv):], data) + + response, err := transmit(s.card, &commandAPDU{ + Cla: cla, + Ins: ins, + P1: p1, + P2: p2, + Data: fulldata, + }) + if err != nil { + return nil, err + } + + rmeta := [16]byte{byte(len(response.Data))} + rmac := response.Data[:len(s.iv)] + rdata := response.Data[len(s.iv):] + plainData, err := s.decryptAPDU(rdata) + if err != nil { + return nil, err + } + + if err = s.updateIV(rmeta[:], rdata); err != nil { + return nil, err + } + if !bytes.Equal(s.iv, rmac) { + return nil, fmt.Errorf("Invalid MAC in response") + } + + rapdu := &responseAPDU{} + rapdu.deserialize(plainData) + + if rapdu.Sw1 != sw1Ok { + return nil, fmt.Errorf("Unexpected response status Cla=0x%x, Ins=0x%x, Sw=0x%x%x", cla, ins, rapdu.Sw1, rapdu.Sw2) + } + + return rapdu, nil +} + +// encryptAPDU is an internal method that serializes and encrypts an APDU. +func (s *SecureChannelSession) encryptAPDU(data []byte) ([]byte, error) { + if len(data) > maxPayloadSize { + return nil, fmt.Errorf("Payload of %d bytes exceeds maximum of %d", len(data), maxPayloadSize) + } + data = pad(data, 0x80) + + ret := make([]byte, len(data)) + + a, err := aes.NewCipher(s.sessionEncKey) + if err != nil { + return nil, err + } + crypter := cipher.NewCBCEncrypter(a, s.iv) + crypter.CryptBlocks(ret, data) + return ret, nil +} + +// pad applies message padding to a 16 byte boundary. +func pad(data []byte, terminator byte) []byte { + padded := make([]byte, (len(data)/16+1)*16) + copy(padded, data) + padded[len(data)] = terminator + return padded +} + +// decryptAPDU is an internal method that decrypts and deserializes an APDU. +func (s *SecureChannelSession) decryptAPDU(data []byte) ([]byte, error) { + a, err := aes.NewCipher(s.sessionEncKey) + if err != nil { + return nil, err + } + + ret := make([]byte, len(data)) + + crypter := cipher.NewCBCDecrypter(a, s.iv) + crypter.CryptBlocks(ret, data) + return unpad(ret, 0x80) +} + +// unpad strips padding from a message. +func unpad(data []byte, terminator byte) ([]byte, error) { + for i := 1; i <= 16; i++ { + switch data[len(data)-i] { + case 0: + continue + case terminator: + return data[:len(data)-i], nil + default: + return nil, fmt.Errorf("Expected end of padding, got %d", data[len(data)-i]) + } + } + return nil, fmt.Errorf("Expected end of padding, got 0") +} + +// updateIV is an internal method that updates the initialization vector after +// each message exchanged. +func (s *SecureChannelSession) updateIV(meta, data []byte) error { + data = pad(data, 0) + a, err := aes.NewCipher(s.sessionMacKey) + if err != nil { + return err + } + crypter := cipher.NewCBCEncrypter(a, make([]byte, 16)) + crypter.CryptBlocks(meta, meta) + crypter.CryptBlocks(data, data) + // The first 16 bytes of the last block is the MAC + s.iv = data[len(data)-32 : len(data)-16] + return nil +} diff --git a/accounts/scwallet/wallet.go b/accounts/scwallet/wallet.go new file mode 100644 index 0000000..f72e685 --- /dev/null +++ b/accounts/scwallet/wallet.go @@ -0,0 +1,1082 @@ +// Copyright 2018 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 scwallet + +import ( + "bytes" + "context" + "crypto/hmac" + "crypto/sha256" + "crypto/sha512" + "encoding/asn1" + "encoding/binary" + "errors" + "fmt" + "math/big" + "regexp" + "sort" + "strings" + "sync" + "time" + + "github.com/ava-labs/coreth/accounts" + "github.com/ava-labs/coreth/core/types" + ethereum "github.com/ava-labs/go-ethereum" + "github.com/ava-labs/go-ethereum/common" + "github.com/ava-labs/go-ethereum/crypto" + "github.com/ava-labs/go-ethereum/log" + pcsc "github.com/gballet/go-libpcsclite" + "github.com/status-im/keycard-go/derivationpath" +) + +// ErrPairingPasswordNeeded is returned if opening the smart card requires pairing with a pairing +// password. In this case, the calling application should request user input to enter +// the pairing password and send it back. +var ErrPairingPasswordNeeded = errors.New("smartcard: pairing password needed") + +// ErrPINNeeded is returned if opening the smart card requires a PIN code. In +// this case, the calling application should request user input to enter the PIN +// and send it back. +var ErrPINNeeded = errors.New("smartcard: pin needed") + +// ErrPINUnblockNeeded is returned if opening the smart card requires a PIN code, +// but all PIN attempts have already been exhausted. In this case the calling +// application should request user input for the PUK and a new PIN code to set +// fo the card. +var ErrPINUnblockNeeded = errors.New("smartcard: pin unblock needed") + +// ErrAlreadyOpen is returned if the smart card is attempted to be opened, but +// there is already a paired and unlocked session. +var ErrAlreadyOpen = errors.New("smartcard: already open") + +// ErrPubkeyMismatch is returned if the public key recovered from a signature +// does not match the one expected by the user. +var ErrPubkeyMismatch = errors.New("smartcard: recovered public key mismatch") + +var ( + appletAID = []byte{0xA0, 0x00, 0x00, 0x08, 0x04, 0x00, 0x01, 0x01, 0x01} + // DerivationSignatureHash is used to derive the public key from the signature of this hash + DerivationSignatureHash = sha256.Sum256(common.Hash{}.Bytes()) +) + +// List of APDU command-related constants +const ( + claISO7816 = 0 + claSCWallet = 0x80 + + insSelect = 0xA4 + insGetResponse = 0xC0 + sw1GetResponse = 0x61 + sw1Ok = 0x90 + + insVerifyPin = 0x20 + insUnblockPin = 0x22 + insExportKey = 0xC2 + insSign = 0xC0 + insLoadKey = 0xD0 + insDeriveKey = 0xD1 + insStatus = 0xF2 +) + +// List of ADPU command parameters +const ( + P1DeriveKeyFromMaster = uint8(0x00) + P1DeriveKeyFromParent = uint8(0x01) + P1DeriveKeyFromCurrent = uint8(0x10) + statusP1WalletStatus = uint8(0x00) + statusP1Path = uint8(0x01) + signP1PrecomputedHash = uint8(0x01) + signP2OnlyBlock = uint8(0x81) + exportP1Any = uint8(0x00) + exportP2Pubkey = uint8(0x01) +) + +// Minimum time to wait between self derivation attempts, even it the user is +// requesting accounts like crazy. +const selfDeriveThrottling = time.Second + +// Wallet represents a smartcard wallet instance. +type Wallet struct { + Hub *Hub // A handle to the Hub that instantiated this wallet. + PublicKey []byte // The wallet's public key (used for communication and identification, not signing!) + + lock sync.Mutex // Lock that gates access to struct fields and communication with the card + card *pcsc.Card // A handle to the smartcard interface for the wallet. + session *Session // The secure communication session with the card + log log.Logger // Contextual logger to tag the base with its id + + deriveNextPaths []accounts.DerivationPath // Next derivation paths for account auto-discovery (multiple bases supported) + deriveNextAddrs []common.Address // Next derived account addresses for auto-discovery (multiple bases supported) + deriveChain ethereum.ChainStateReader // Blockchain state reader to discover used account with + deriveReq chan chan struct{} // Channel to request a self-derivation on + deriveQuit chan chan error // Channel to terminate the self-deriver with +} + +// NewWallet constructs and returns a new Wallet instance. +func NewWallet(hub *Hub, card *pcsc.Card) *Wallet { + wallet := &Wallet{ + Hub: hub, + card: card, + } + return wallet +} + +// transmit sends an APDU to the smartcard and receives and decodes the response. +// It automatically handles requests by the card to fetch the return data separately, +// and returns an error if the response status code is not success. +func transmit(card *pcsc.Card, command *commandAPDU) (*responseAPDU, error) { + data, err := command.serialize() + if err != nil { + return nil, err + } + + responseData, _, err := card.Transmit(data) + if err != nil { + return nil, err + } + + response := new(responseAPDU) + if err = response.deserialize(responseData); err != nil { + return nil, err + } + + // Are we being asked to fetch the response separately? + if response.Sw1 == sw1GetResponse && (command.Cla != claISO7816 || command.Ins != insGetResponse) { + return transmit(card, &commandAPDU{ + Cla: claISO7816, + Ins: insGetResponse, + P1: 0, + P2: 0, + Data: nil, + Le: response.Sw2, + }) + } + + if response.Sw1 != sw1Ok { + return nil, fmt.Errorf("Unexpected insecure response status Cla=0x%x, Ins=0x%x, Sw=0x%x%x", command.Cla, command.Ins, response.Sw1, response.Sw2) + } + + return response, nil +} + +// applicationInfo encodes information about the smartcard application - its +// instance UID and public key. +type applicationInfo struct { + InstanceUID []byte `asn1:"tag:15"` + PublicKey []byte `asn1:"tag:0"` +} + +// connect connects to the wallet application and establishes a secure channel with it. +// must be called before any other interaction with the wallet. +func (w *Wallet) connect() error { + w.lock.Lock() + defer w.lock.Unlock() + + appinfo, err := w.doselect() + if err != nil { + return err + } + + channel, err := NewSecureChannelSession(w.card, appinfo.PublicKey) + if err != nil { + return err + } + + w.PublicKey = appinfo.PublicKey + w.log = log.New("url", w.URL()) + w.session = &Session{ + Wallet: w, + Channel: channel, + } + return nil +} + +// doselect is an internal (unlocked) function to send a SELECT APDU to the card. +func (w *Wallet) doselect() (*applicationInfo, error) { + response, err := transmit(w.card, &commandAPDU{ + Cla: claISO7816, + Ins: insSelect, + P1: 4, + P2: 0, + Data: appletAID, + }) + if err != nil { + return nil, err + } + + appinfo := new(applicationInfo) + if _, err := asn1.UnmarshalWithParams(response.Data, appinfo, "tag:4"); err != nil { + return nil, err + } + return appinfo, nil +} + +// ping checks the card's status and returns an error if unsuccessful. +func (w *Wallet) ping() error { + w.lock.Lock() + defer w.lock.Unlock() + + // We can't ping if not paired + if !w.session.paired() { + return nil + } + if _, err := w.session.walletStatus(); err != nil { + return err + } + return nil +} + +// release releases any resources held by an open wallet instance. +func (w *Wallet) release() error { + if w.session != nil { + return w.session.release() + } + return nil +} + +// pair is an internal (unlocked) function for establishing a new pairing +// with the wallet. +func (w *Wallet) pair(puk []byte) error { + if w.session.paired() { + return fmt.Errorf("Wallet already paired") + } + pairing, err := w.session.pair(puk) + if err != nil { + return err + } + if err = w.Hub.setPairing(w, &pairing); err != nil { + return err + } + return w.session.authenticate(pairing) +} + +// Unpair deletes an existing wallet pairing. +func (w *Wallet) Unpair(pin []byte) error { + w.lock.Lock() + defer w.lock.Unlock() + + if !w.session.paired() { + return fmt.Errorf("wallet %x not paired", w.PublicKey) + } + if err := w.session.verifyPin(pin); err != nil { + return fmt.Errorf("failed to verify pin: %s", err) + } + if err := w.session.unpair(); err != nil { + return fmt.Errorf("failed to unpair: %s", err) + } + if err := w.Hub.setPairing(w, nil); err != nil { + return err + } + return nil +} + +// URL retrieves the canonical path under which this wallet is reachable. It is +// user by upper layers to define a sorting order over all wallets from multiple +// backends. +func (w *Wallet) URL() accounts.URL { + return accounts.URL{ + Scheme: w.Hub.scheme, + Path: fmt.Sprintf("%x", w.PublicKey[1:5]), // Byte #0 isn't unique; 1:5 covers << 64K cards, bump to 1:9 for << 4M + } +} + +// Status returns a textual status to aid the user in the current state of the +// wallet. It also returns an error indicating any failure the wallet might have +// encountered. +func (w *Wallet) Status() (string, error) { + w.lock.Lock() + defer w.lock.Unlock() + + // If the card is not paired, we can only wait + if !w.session.paired() { + return "Unpaired, waiting for pairing password", nil + } + // Yay, we have an encrypted session, retrieve the actual status + status, err := w.session.walletStatus() + if err != nil { + return fmt.Sprintf("Failed: %v", err), err + } + switch { + case !w.session.verified && status.PinRetryCount == 0 && status.PukRetryCount == 0: + return fmt.Sprintf("Bricked, waiting for full wipe"), nil + case !w.session.verified && status.PinRetryCount == 0: + return fmt.Sprintf("Blocked, waiting for PUK (%d attempts left) and new PIN", status.PukRetryCount), nil + case !w.session.verified: + return fmt.Sprintf("Locked, waiting for PIN (%d attempts left)", status.PinRetryCount), nil + case !status.Initialized: + return fmt.Sprintf("Empty, waiting for initialization"), nil + default: + return fmt.Sprintf("Online"), nil + } +} + +// Open initializes access to a wallet instance. It is not meant to unlock or +// decrypt account keys, rather simply to establish a connection to hardware +// wallets and/or to access derivation seeds. +// +// The passphrase parameter may or may not be used by the implementation of a +// particular wallet instance. The reason there is no passwordless open method +// is to strive towards a uniform wallet handling, oblivious to the different +// backend providers. +// +// Please note, if you open a wallet, you must close it to release any allocated +// resources (especially important when working with hardware wallets). +func (w *Wallet) Open(passphrase string) error { + w.lock.Lock() + defer w.lock.Unlock() + + // If the session is already open, bail out + if w.session.verified { + return ErrAlreadyOpen + } + // If the smart card is not yet paired, attempt to do so either from a previous + // pairing key or form the supplied PUK code. + if !w.session.paired() { + // If a previous pairing exists, only ever try to use that + if pairing := w.Hub.pairing(w); pairing != nil { + if err := w.session.authenticate(*pairing); err != nil { + return fmt.Errorf("failed to authenticate card %x: %s", w.PublicKey[:4], err) + } + // Pairing still ok, fall through to PIN checks + } else { + // If no passphrase was supplied, request the PUK from the user + if passphrase == "" { + return ErrPairingPasswordNeeded + } + // Attempt to pair the smart card with the user supplied PUK + if err := w.pair([]byte(passphrase)); err != nil { + return err + } + // Pairing succeeded, fall through to PIN checks. This will of course fail, + // but we can't return ErrPINNeeded directly here becase we don't know whether + // a PIN check or a PIN reset is needed. + passphrase = "" + } + } + // The smart card was successfully paired, retrieve its status to check whether + // PIN verification or unblocking is needed. + status, err := w.session.walletStatus() + if err != nil { + return err + } + // Request the appropriate next authentication data, or use the one supplied + switch { + case passphrase == "" && status.PinRetryCount > 0: + return ErrPINNeeded + case passphrase == "": + return ErrPINUnblockNeeded + case status.PinRetryCount > 0: + if !regexp.MustCompile(`^[0-9]{6,}$`).MatchString(passphrase) { + w.log.Error("PIN needs to be at least 6 digits") + return ErrPINNeeded + } + if err := w.session.verifyPin([]byte(passphrase)); err != nil { + return err + } + default: + if !regexp.MustCompile(`^[0-9]{12,}$`).MatchString(passphrase) { + w.log.Error("PUK needs to be at least 12 digits") + return ErrPINUnblockNeeded + } + if err := w.session.unblockPin([]byte(passphrase)); err != nil { + return err + } + } + // Smart card paired and unlocked, initialize and register + w.deriveReq = make(chan chan struct{}) + w.deriveQuit = make(chan chan error) + + go w.selfDerive() + + // Notify anyone listening for wallet events that a new device is accessible + go w.Hub.updateFeed.Send(accounts.WalletEvent{Wallet: w, Kind: accounts.WalletOpened}) + + return nil +} + +// Close stops and closes the wallet, freeing any resources. +func (w *Wallet) Close() error { + // Ensure the wallet was opened + w.lock.Lock() + dQuit := w.deriveQuit + w.lock.Unlock() + + // Terminate the self-derivations + var derr error + if dQuit != nil { + errc := make(chan error) + dQuit <- errc + derr = <-errc // Save for later, we *must* close the USB + } + // Terminate the device connection + w.lock.Lock() + defer w.lock.Unlock() + + w.deriveQuit = nil + w.deriveReq = nil + + if err := w.release(); err != nil { + return err + } + return derr +} + +// selfDerive is an account derivation loop that upon request attempts to find +// new non-zero accounts. +func (w *Wallet) selfDerive() { + w.log.Debug("Smart card wallet self-derivation started") + defer w.log.Debug("Smart card wallet self-derivation stopped") + + // Execute self-derivations until termination or error + var ( + reqc chan struct{} + errc chan error + err error + ) + for errc == nil && err == nil { + // Wait until either derivation or termination is requested + select { + case errc = <-w.deriveQuit: + // Termination requested + continue + case reqc = <-w.deriveReq: + // Account discovery requested + } + // Derivation needs a chain and device access, skip if either unavailable + w.lock.Lock() + if w.session == nil || w.deriveChain == nil { + w.lock.Unlock() + reqc <- struct{}{} + continue + } + pairing := w.Hub.pairing(w) + + // Device lock obtained, derive the next batch of accounts + var ( + paths []accounts.DerivationPath + nextAcc accounts.Account + + nextPaths = append([]accounts.DerivationPath{}, w.deriveNextPaths...) + nextAddrs = append([]common.Address{}, w.deriveNextAddrs...) + + context = context.Background() + ) + for i := 0; i < len(nextAddrs); i++ { + for empty := false; !empty; { + // Retrieve the next derived Ethereum account + if nextAddrs[i] == (common.Address{}) { + if nextAcc, err = w.session.derive(nextPaths[i]); err != nil { + w.log.Warn("Smartcard wallet account derivation failed", "err", err) + break + } + nextAddrs[i] = nextAcc.Address + } + // Check the account's status against the current chain state + var ( + balance *big.Int + nonce uint64 + ) + balance, err = w.deriveChain.BalanceAt(context, nextAddrs[i], nil) + if err != nil { + w.log.Warn("Smartcard wallet balance retrieval failed", "err", err) + break + } + nonce, err = w.deriveChain.NonceAt(context, nextAddrs[i], nil) + if err != nil { + w.log.Warn("Smartcard wallet nonce retrieval failed", "err", err) + break + } + // If the next account is empty, stop self-derivation, but add for the last base path + if balance.Sign() == 0 && nonce == 0 { + empty = true + if i < len(nextAddrs)-1 { + break + } + } + // We've just self-derived a new account, start tracking it locally + path := make(accounts.DerivationPath, len(nextPaths[i])) + copy(path[:], nextPaths[i][:]) + paths = append(paths, path) + + // Display a log message to the user for new (or previously empty accounts) + if _, known := pairing.Accounts[nextAddrs[i]]; !known || !empty || nextAddrs[i] != w.deriveNextAddrs[i] { + w.log.Info("Smartcard wallet discovered new account", "address", nextAddrs[i], "path", path, "balance", balance, "nonce", nonce) + } + pairing.Accounts[nextAddrs[i]] = path + + // Fetch the next potential account + if !empty { + nextAddrs[i] = common.Address{} + nextPaths[i][len(nextPaths[i])-1]++ + } + } + } + // If there are new accounts, write them out + if len(paths) > 0 { + err = w.Hub.setPairing(w, pairing) + } + // Shift the self-derivation forward + w.deriveNextAddrs = nextAddrs + w.deriveNextPaths = nextPaths + + // Self derivation complete, release device lock + w.lock.Unlock() + + // Notify the user of termination and loop after a bit of time (to avoid trashing) + reqc <- struct{}{} + if err == nil { + select { + case errc = <-w.deriveQuit: + // Termination requested, abort + case <-time.After(selfDeriveThrottling): + // Waited enough, willing to self-derive again + } + } + } + // In case of error, wait for termination + if err != nil { + w.log.Debug("Smartcard wallet self-derivation failed", "err", err) + errc = <-w.deriveQuit + } + errc <- err +} + +// Accounts retrieves the list of signing accounts the wallet is currently aware +// of. For hierarchical deterministic wallets, the list will not be exhaustive, +// rather only contain the accounts explicitly pinned during account derivation. +func (w *Wallet) Accounts() []accounts.Account { + // Attempt self-derivation if it's running + reqc := make(chan struct{}, 1) + select { + case w.deriveReq <- reqc: + // Self-derivation request accepted, wait for it + <-reqc + default: + // Self-derivation offline, throttled or busy, skip + } + + w.lock.Lock() + defer w.lock.Unlock() + + if pairing := w.Hub.pairing(w); pairing != nil { + ret := make([]accounts.Account, 0, len(pairing.Accounts)) + for address, path := range pairing.Accounts { + ret = append(ret, w.makeAccount(address, path)) + } + sort.Sort(accounts.AccountsByURL(ret)) + return ret + } + return nil +} + +func (w *Wallet) makeAccount(address common.Address, path accounts.DerivationPath) accounts.Account { + return accounts.Account{ + Address: address, + URL: accounts.URL{ + Scheme: w.Hub.scheme, + Path: fmt.Sprintf("%x/%s", w.PublicKey[1:3], path.String()), + }, + } +} + +// Contains returns whether an account is part of this particular wallet or not. +func (w *Wallet) Contains(account accounts.Account) bool { + if pairing := w.Hub.pairing(w); pairing != nil { + _, ok := pairing.Accounts[account.Address] + return ok + } + return false +} + +// Initialize installs a keypair generated from the provided key into the wallet. +func (w *Wallet) Initialize(seed []byte) error { + go w.selfDerive() + // DO NOT lock at this stage, as the initialize + // function relies on Status() + return w.session.initialize(seed) +} + +// Derive attempts to explicitly derive a hierarchical deterministic account at +// the specified derivation path. If requested, the derived account will be added +// to the wallet's tracked account list. +func (w *Wallet) Derive(path accounts.DerivationPath, pin bool) (accounts.Account, error) { + w.lock.Lock() + defer w.lock.Unlock() + + account, err := w.session.derive(path) + if err != nil { + return accounts.Account{}, err + } + + if pin { + pairing := w.Hub.pairing(w) + pairing.Accounts[account.Address] = path + if err := w.Hub.setPairing(w, pairing); err != nil { + return accounts.Account{}, err + } + } + + return account, nil +} + +// SelfDerive sets a base account derivation path from which the wallet attempts +// to discover non zero accounts and automatically add them to list of tracked +// accounts. +// +// Note, self derivaton will increment the last component of the specified path +// opposed to decending into a child path to allow discovering accounts starting +// from non zero components. +// +// Some hardware wallets switched derivation paths through their evolution, so +// this method supports providing multiple bases to discover old user accounts +// too. Only the last base will be used to derive the next empty account. +// +// You can disable automatic account discovery by calling SelfDerive with a nil +// chain state reader. +func (w *Wallet) SelfDerive(bases []accounts.DerivationPath, chain ethereum.ChainStateReader) { + w.lock.Lock() + defer w.lock.Unlock() + + w.deriveNextPaths = make([]accounts.DerivationPath, len(bases)) + for i, base := range bases { + w.deriveNextPaths[i] = make(accounts.DerivationPath, len(base)) + copy(w.deriveNextPaths[i][:], base[:]) + } + w.deriveNextAddrs = make([]common.Address, len(bases)) + w.deriveChain = chain +} + +// SignData requests the wallet to sign the hash of the given data. +// +// It looks up the account specified either solely via its address contained within, +// or optionally with the aid of any location metadata from the embedded URL field. +// +// If the wallet requires additional authentication to sign the request (e.g. +// a password to decrypt the account, or a PIN code o verify the transaction), +// an AuthNeededError instance will be returned, containing infos for the user +// about which fields or actions are needed. The user may retry by providing +// the needed details via SignDataWithPassphrase, or by other means (e.g. unlock +// the account in a keystore). +func (w *Wallet) SignData(account accounts.Account, mimeType string, data []byte) ([]byte, error) { + return w.signHash(account, crypto.Keccak256(data)) +} + +func (w *Wallet) signHash(account accounts.Account, hash []byte) ([]byte, error) { + w.lock.Lock() + defer w.lock.Unlock() + + path, err := w.findAccountPath(account) + if err != nil { + return nil, err + } + + return w.session.sign(path, hash) +} + +// SignTx requests the wallet to sign the given transaction. +// +// It looks up the account specified either solely via its address contained within, +// or optionally with the aid of any location metadata from the embedded URL field. +// +// If the wallet requires additional authentication to sign the request (e.g. +// a password to decrypt the account, or a PIN code o verify the transaction), +// an AuthNeededError instance will be returned, containing infos for the user +// about which fields or actions are needed. The user may retry by providing +// the needed details via SignTxWithPassphrase, or by other means (e.g. unlock +// the account in a keystore). +func (w *Wallet) SignTx(account accounts.Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) { + signer := types.NewEIP155Signer(chainID) + hash := signer.Hash(tx) + sig, err := w.signHash(account, hash[:]) + if err != nil { + return nil, err + } + return tx.WithSignature(signer, sig) +} + +// SignDataWithPassphrase requests the wallet to sign the given hash with the +// given passphrase as extra authentication information. +// +// It looks up the account specified either solely via its address contained within, +// or optionally with the aid of any location metadata from the embedded URL field. +func (w *Wallet) SignDataWithPassphrase(account accounts.Account, passphrase, mimeType string, data []byte) ([]byte, error) { + return w.signHashWithPassphrase(account, passphrase, crypto.Keccak256(data)) +} + +func (w *Wallet) signHashWithPassphrase(account accounts.Account, passphrase string, hash []byte) ([]byte, error) { + if !w.session.verified { + if err := w.Open(passphrase); err != nil { + return nil, err + } + } + + return w.signHash(account, hash) +} + +// SignText requests the wallet to sign the hash of a given piece of data, prefixed +// by the Ethereum prefix scheme +// It looks up the account specified either solely via its address contained within, +// or optionally with the aid of any location metadata from the embedded URL field. +// +// If the wallet requires additional authentication to sign the request (e.g. +// a password to decrypt the account, or a PIN code o verify the transaction), +// an AuthNeededError instance will be returned, containing infos for the user +// about which fields or actions are needed. The user may retry by providing +// the needed details via SignHashWithPassphrase, or by other means (e.g. unlock +// the account in a keystore). +func (w *Wallet) SignText(account accounts.Account, text []byte) ([]byte, error) { + return w.signHash(account, accounts.TextHash(text)) +} + +// SignTextWithPassphrase implements accounts.Wallet, attempting to sign the +// given hash with the given account using passphrase as extra authentication +func (w *Wallet) SignTextWithPassphrase(account accounts.Account, passphrase string, text []byte) ([]byte, error) { + return w.signHashWithPassphrase(account, passphrase, crypto.Keccak256(accounts.TextHash(text))) +} + +// SignTxWithPassphrase requests the wallet to sign the given transaction, with the +// given passphrase as extra authentication information. +// +// It looks up the account specified either solely via its address contained within, +// or optionally with the aid of any location metadata from the embedded URL field. +func (w *Wallet) SignTxWithPassphrase(account accounts.Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) { + if !w.session.verified { + if err := w.Open(passphrase); err != nil { + return nil, err + } + } + return w.SignTx(account, tx, chainID) +} + +// findAccountPath returns the derivation path for the provided account. +// It first checks for the address in the list of pinned accounts, and if it is +// not found, attempts to parse the derivation path from the account's URL. +func (w *Wallet) findAccountPath(account accounts.Account) (accounts.DerivationPath, error) { + pairing := w.Hub.pairing(w) + if path, ok := pairing.Accounts[account.Address]; ok { + return path, nil + } + + // Look for the path in the URL + if account.URL.Scheme != w.Hub.scheme { + return nil, fmt.Errorf("Scheme %s does not match wallet scheme %s", account.URL.Scheme, w.Hub.scheme) + } + + parts := strings.SplitN(account.URL.Path, "/", 2) + if len(parts) != 2 { + return nil, fmt.Errorf("Invalid URL format: %s", account.URL) + } + + if parts[0] != fmt.Sprintf("%x", w.PublicKey[1:3]) { + return nil, fmt.Errorf("URL %s is not for this wallet", account.URL) + } + + return accounts.ParseDerivationPath(parts[1]) +} + +// Session represents a secured communication session with the wallet. +type Session struct { + Wallet *Wallet // A handle to the wallet that opened the session + Channel *SecureChannelSession // A secure channel for encrypted messages + verified bool // Whether the pin has been verified in this session. +} + +// pair establishes a new pairing over this channel, using the provided secret. +func (s *Session) pair(secret []byte) (smartcardPairing, error) { + err := s.Channel.Pair(secret) + if err != nil { + return smartcardPairing{}, err + } + + return smartcardPairing{ + PublicKey: s.Wallet.PublicKey, + PairingIndex: s.Channel.PairingIndex, + PairingKey: s.Channel.PairingKey, + Accounts: make(map[common.Address]accounts.DerivationPath), + }, nil +} + +// unpair deletes an existing pairing. +func (s *Session) unpair() error { + if !s.verified { + return fmt.Errorf("Unpair requires that the PIN be verified") + } + return s.Channel.Unpair() +} + +// verifyPin unlocks a wallet with the provided pin. +func (s *Session) verifyPin(pin []byte) error { + if _, err := s.Channel.transmitEncrypted(claSCWallet, insVerifyPin, 0, 0, pin); err != nil { + return err + } + s.verified = true + return nil +} + +// unblockPin unblocks a wallet with the provided puk and resets the pin to the +// new one specified. +func (s *Session) unblockPin(pukpin []byte) error { + if _, err := s.Channel.transmitEncrypted(claSCWallet, insUnblockPin, 0, 0, pukpin); err != nil { + return err + } + s.verified = true + return nil +} + +// release releases resources associated with the channel. +func (s *Session) release() error { + return s.Wallet.card.Disconnect(pcsc.LeaveCard) +} + +// paired returns true if a valid pairing exists. +func (s *Session) paired() bool { + return s.Channel.PairingKey != nil +} + +// authenticate uses an existing pairing to establish a secure channel. +func (s *Session) authenticate(pairing smartcardPairing) error { + if !bytes.Equal(s.Wallet.PublicKey, pairing.PublicKey) { + return fmt.Errorf("Cannot pair using another wallet's pairing; %x != %x", s.Wallet.PublicKey, pairing.PublicKey) + } + s.Channel.PairingKey = pairing.PairingKey + s.Channel.PairingIndex = pairing.PairingIndex + return s.Channel.Open() +} + +// walletStatus describes a smartcard wallet's status information. +type walletStatus struct { + PinRetryCount int // Number of remaining PIN retries + PukRetryCount int // Number of remaining PUK retries + Initialized bool // Whether the card has been initialized with a private key +} + +// walletStatus fetches the wallet's status from the card. +func (s *Session) walletStatus() (*walletStatus, error) { + response, err := s.Channel.transmitEncrypted(claSCWallet, insStatus, statusP1WalletStatus, 0, nil) + if err != nil { + return nil, err + } + + status := new(walletStatus) + if _, err := asn1.UnmarshalWithParams(response.Data, status, "tag:3"); err != nil { + return nil, err + } + return status, nil +} + +// derivationPath fetches the wallet's current derivation path from the card. +func (s *Session) derivationPath() (accounts.DerivationPath, error) { + response, err := s.Channel.transmitEncrypted(claSCWallet, insStatus, statusP1Path, 0, nil) + if err != nil { + return nil, err + } + buf := bytes.NewReader(response.Data) + path := make(accounts.DerivationPath, len(response.Data)/4) + return path, binary.Read(buf, binary.BigEndian, &path) +} + +// initializeData contains data needed to initialize the smartcard wallet. +type initializeData struct { + PublicKey []byte `asn1:"tag:0"` + PrivateKey []byte `asn1:"tag:1"` + ChainCode []byte `asn1:"tag:2"` +} + +// initialize initializes the card with new key data. +func (s *Session) initialize(seed []byte) error { + // Check that the wallet isn't currently initialized, + // otherwise the key would be overwritten. + status, err := s.Wallet.Status() + if err != nil { + return err + } + if status == "Online" { + return fmt.Errorf("card is already initialized, cowardly refusing to proceed") + } + + s.Wallet.lock.Lock() + defer s.Wallet.lock.Unlock() + + // HMAC the seed to produce the private key and chain code + mac := hmac.New(sha512.New, []byte("Bitcoin seed")) + mac.Write(seed) + seed = mac.Sum(nil) + + key, err := crypto.ToECDSA(seed[:32]) + if err != nil { + return err + } + + id := initializeData{} + id.PublicKey = crypto.FromECDSAPub(&key.PublicKey) + id.PrivateKey = seed[:32] + id.ChainCode = seed[32:] + data, err := asn1.Marshal(id) + if err != nil { + return err + } + + // Nasty hack to force the top-level struct tag to be context-specific + data[0] = 0xA1 + + _, err = s.Channel.transmitEncrypted(claSCWallet, insLoadKey, 0x02, 0, data) + return err +} + +// derive derives a new HD key path on the card. +func (s *Session) derive(path accounts.DerivationPath) (accounts.Account, error) { + startingPoint, path, err := derivationpath.Decode(path.String()) + if err != nil { + return accounts.Account{}, err + } + + var p1 uint8 + switch startingPoint { + case derivationpath.StartingPointMaster: + p1 = P1DeriveKeyFromMaster + case derivationpath.StartingPointParent: + p1 = P1DeriveKeyFromParent + case derivationpath.StartingPointCurrent: + p1 = P1DeriveKeyFromCurrent + default: + return accounts.Account{}, fmt.Errorf("invalid startingPoint %d", startingPoint) + } + + data := new(bytes.Buffer) + for _, segment := range path { + if err := binary.Write(data, binary.BigEndian, segment); err != nil { + return accounts.Account{}, err + } + } + + _, err = s.Channel.transmitEncrypted(claSCWallet, insDeriveKey, p1, 0, data.Bytes()) + if err != nil { + return accounts.Account{}, err + } + + response, err := s.Channel.transmitEncrypted(claSCWallet, insSign, 0, 0, DerivationSignatureHash[:]) + if err != nil { + return accounts.Account{}, err + } + + sigdata := new(signatureData) + if _, err := asn1.UnmarshalWithParams(response.Data, sigdata, "tag:0"); err != nil { + return accounts.Account{}, err + } + rbytes, sbytes := sigdata.Signature.R.Bytes(), sigdata.Signature.S.Bytes() + sig := make([]byte, 65) + copy(sig[32-len(rbytes):32], rbytes) + copy(sig[64-len(sbytes):64], sbytes) + + if err := confirmPublicKey(sig, sigdata.PublicKey); err != nil { + return accounts.Account{}, err + } + pub, err := crypto.UnmarshalPubkey(sigdata.PublicKey) + if err != nil { + return accounts.Account{}, err + } + return s.Wallet.makeAccount(crypto.PubkeyToAddress(*pub), path), nil +} + +// keyExport contains information on an exported keypair. +type keyExport struct { + PublicKey []byte `asn1:"tag:0"` + PrivateKey []byte `asn1:"tag:1,optional"` +} + +// publicKey returns the public key for the current derivation path. +func (s *Session) publicKey() ([]byte, error) { + response, err := s.Channel.transmitEncrypted(claSCWallet, insExportKey, exportP1Any, exportP2Pubkey, nil) + if err != nil { + return nil, err + } + keys := new(keyExport) + if _, err := asn1.UnmarshalWithParams(response.Data, keys, "tag:1"); err != nil { + return nil, err + } + return keys.PublicKey, nil +} + +// signatureData contains information on a signature - the signature itself and +// the corresponding public key. +type signatureData struct { + PublicKey []byte `asn1:"tag:0"` + Signature struct { + R *big.Int + S *big.Int + } +} + +// sign asks the card to sign a message, and returns a valid signature after +// recovering the v value. +func (s *Session) sign(path accounts.DerivationPath, hash []byte) ([]byte, error) { + startTime := time.Now() + _, err := s.derive(path) + if err != nil { + return nil, err + } + deriveTime := time.Now() + + response, err := s.Channel.transmitEncrypted(claSCWallet, insSign, signP1PrecomputedHash, signP2OnlyBlock, hash) + if err != nil { + return nil, err + } + sigdata := new(signatureData) + if _, err := asn1.UnmarshalWithParams(response.Data, sigdata, "tag:0"); err != nil { + return nil, err + } + // Serialize the signature + rbytes, sbytes := sigdata.Signature.R.Bytes(), sigdata.Signature.S.Bytes() + sig := make([]byte, 65) + copy(sig[32-len(rbytes):32], rbytes) + copy(sig[64-len(sbytes):64], sbytes) + + // Recover the V value. + sig, err = makeRecoverableSignature(hash, sig, sigdata.PublicKey) + if err != nil { + return nil, err + } + log.Debug("Signed using smartcard", "deriveTime", deriveTime.Sub(startTime), "signingTime", time.Since(deriveTime)) + + return sig, nil +} + +// confirmPublicKey confirms that the given signature belongs to the specified key. +func confirmPublicKey(sig, pubkey []byte) error { + _, err := makeRecoverableSignature(DerivationSignatureHash[:], sig, pubkey) + return err +} + +// makeRecoverableSignature uses a signature and an expected public key to +// recover the v value and produce a recoverable signature. +func makeRecoverableSignature(hash, sig, expectedPubkey []byte) ([]byte, error) { + var libraryError error + for v := 0; v < 2; v++ { + sig[64] = byte(v) + if pubkey, err := crypto.Ecrecover(hash, sig); err == nil { + if bytes.Equal(pubkey, expectedPubkey) { + return sig, nil + } + } else { + libraryError = err + } + } + if libraryError != nil { + return nil, libraryError + } + return nil, ErrPubkeyMismatch +} |