path: root/accounts/keystore/keystore.go

// 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/>.

// Package keystore implements encrypted storage of secp256k1 private keys.
//
// Keys are stored as encrypted JSON files according to the Web3 Secret Storage specification.
// See https://github.com/ethereum/wiki/wiki/Web3-Secret-Storage-Definition for more information.
package keystore

import (
    "crypto/ecdsa"
    crand "crypto/rand"
    "errors"
    "fmt"
    "math/big"
    "os"
    "path/filepath"
    "reflect"
    "runtime"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/accounts"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/event"
)

var (
    ErrLocked  = accounts.NewAuthNeededError("password or unlock")
    ErrNoMatch = errors.New("no key for given address or file")
    ErrDecrypt = errors.New("could not decrypt key with given passphrase")
)

// KeyStoreType is the reflect type of a keystore backend.
var KeyStoreType = reflect.TypeOf(&KeyStore{})

// KeyStoreScheme is the protocol scheme prefixing account and wallet URLs.
var KeyStoreScheme = "keystore"

// Maximum time between wallet refreshes (if filesystem notifications don't work).
const walletRefreshCycle = 3 * time.Second

// KeyStore manages a key storage directory on disk.
type KeyStore struct {
    storage  keyStore                     // Storage backend, might be cleartext or encrypted
    cache    *accountCache                // In-memory account cache over the filesystem storage
    changes  chan struct{}                // Channel receiving change notifications from the cache
    unlocked map[common.Address]*unlocked // Currently unlocked account (decrypted private keys)

    wallets     []accounts.Wallet       // Wallet wrappers around the individual key files
    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

    mu sync.RWMutex
}

type unlocked struct {
    *Key
    abort chan struct{}
}

// NewKeyStore creates a keystore for the given directory.
func NewKeyStore(keydir string, scryptN, scryptP int) *KeyStore {
    keydir, _ = filepath.Abs(keydir)
    ks := &KeyStore{storage: &keyStorePassphrase{keydir, scryptN, scryptP}}
    ks.init(keydir)
    return ks
}

// NewPlaintextKeyStore creates a keystore for the given directory.
// Deprecated: Use NewKeyStore.
func NewPlaintextKeyStore(keydir string) *KeyStore {
    keydir, _ = filepath.Abs(keydir)
    ks := &KeyStore{storage: &keyStorePlain{keydir}}
    ks.init(keydir)
    return ks
}

func (ks *KeyStore) init(keydir string) {
    // Lock the mutex since the account cache might call back with events
    ks.mu.Lock()
    defer ks.mu.Unlock()

    // Initialize the set of unlocked keys and the account cache
    ks.unlocked = make(map[common.Address]*unlocked)
    ks.cache, ks.changes = newAccountCache(keydir)

    // TODO: In order for this finalizer to work, there must be no references
    // to ks. addressCache doesn't keep a reference but unlocked keys do,
    // so the finalizer will not trigger until all timed unlocks have expired.
    runtime.SetFinalizer(ks, func(m *KeyStore) {
        m.cache.close()
    })
    // Create the initial list of wallets from the cache
    accs := ks.cache.accounts()
    ks.wallets = make([]accounts.Wallet, len(accs))
    for i := 0; i < len(accs); i++ {
        ks.wallets[i] = &keystoreWallet{account: accs[i], keystore: ks}
    }
}

// Wallets implements accounts.Backend, returning all single-key wallets from the
// keystore directory.
func (ks *KeyStore) Wallets() []accounts.Wallet {
    // Make sure the list of wallets is in sync with the account cache
    ks.refreshWallets()

    ks.mu.RLock()
    defer ks.mu.RUnlock()

    cpy := make([]accounts.Wallet, len(ks.wallets))
    copy(cpy, ks.wallets)
    return cpy
}

// refreshWallets retrieves the current account list and based on that does any
// necessary wallet refreshes.
func (ks *KeyStore) refreshWallets() {
    // Retrieve the current list of accounts
    ks.mu.Lock()
    accs := ks.cache.accounts()

    // Transform the current list of wallets into the new one
    wallets := make([]accounts.Wallet, 0, len(accs))
    events := []accounts.WalletEvent{}

    for _, account := range accs {
        // Drop wallets while they were in front of the next account
        for len(ks.wallets) > 0 && ks.wallets[0].URL().Cmp(account.URL) < 0 {
            events = append(events, accounts.WalletEvent{Wallet: ks.wallets[0], Kind: accounts.WalletDropped})
            ks.wallets = ks.wallets[1:]
        }
        // If there are no more wallets or the account is before the next, wrap new wallet
        if len(ks.wallets) == 0 || ks.wallets[0].URL().Cmp(account.URL) > 0 {
            wallet := &keystoreWallet{account: account, keystore: ks}

            events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletArrived})
            wallets = append(wallets, wallet)
            continue
        }
        // If the account is the same as the first wallet, keep it
        if ks.wallets[0].Accounts()[0] == account {
            wallets = append(wallets, ks.wallets[0])
            ks.wallets = ks.wallets[1:]
            continue
        }
    }
    // Drop any leftover wallets and set the new batch
    for _, wallet := range ks.wallets {
        events = append(events, accounts.WalletEvent{Wallet: wallet, Kind: accounts.WalletDropped})
    }
    ks.wallets = wallets
    ks.mu.Unlock()

    // Fire all wallet events and return
    for _, event := range events {
        ks.updateFeed.Send(event)
    }
}

// Subscribe implements accounts.Backend, creating an async subscription to
// receive notifications on the addition or removal of keystore wallets.
func (ks *KeyStore) Subscribe(sink chan<- accounts.WalletEvent) event.Subscription {
    // We need the mutex to reliably start/stop the update loop
    ks.mu.Lock()
    defer ks.mu.Unlock()

    // Subscribe the caller and track the subscriber count
    sub := ks.updateScope.Track(ks.updateFeed.Subscribe(sink))

    // Subscribers require an active notification loop, start it
    if !ks.updating {
        ks.updating = true
        go ks.updater()
    }
    return sub
}

// updater is responsible for maintaining an up-to-date list of wallets stored in
// the keystore, and for firing wallet addition/removal events. It listens for
// account change events from the underlying account cache, and also periodically
// forces a manual refresh (only triggers for systems where the filesystem notifier
// is not running).
func (ks *KeyStore) updater() {
    for {
        // Wait for an account update or a refresh timeout
        select {
        case <-ks.changes:
        case <-time.After(walletRefreshCycle):
        }
        // Run the wallet refresher
        ks.refreshWallets()

        // If all our subscribers left, stop the updater
        ks.mu.Lock()
        if ks.updateScope.Count() == 0 {
            ks.updating = false
            ks.mu.Unlock()
            return
        }
        ks.mu.Unlock()
    }
}

// HasAddress reports whether a key with the given address is present.
func (ks *KeyStore) HasAddress(addr common.Address) bool {
    return ks.cache.hasAddress(addr)
}

// Accounts returns all key files present in the directory.
func (ks *KeyStore) Accounts() []accounts.Account {
    return ks.cache.accounts()
}

// Delete deletes the key matched by account if the passphrase is correct.
// If the account contains no filename, the address must match a unique key.
func (ks *KeyStore) Delete(a accounts.Account, passphrase string) error {
    // Decrypting the key isn't really necessary, but we do
    // it anyway to check the password and zero out the key
    // immediately afterwards.
    a, key, err := ks.getDecryptedKey(a, passphrase)
    if key != nil {
        zeroKey(key.PrivateKey)
    }
    if err != nil {
        return err
    }
    // The order is crucial here. The key is dropped from the
    // cache after the file is gone so that a reload happening in
    // between won't insert it into the cache again.
    err = os.Remove(a.URL.Path)
    if err == nil {
        ks.cache.delete(a)
        ks.refreshWallets()
    }
    return err
}

// SignHash calculates a ECDSA signature for the given hash. The produced
// signature is in the [R || S || V] format where V is 0 or 1.
func (ks *KeyStore) SignHash(a accounts.Account, hash []byte) ([]byte, error) {
    // Look up the key to sign with and abort if it cannot be found
    ks.mu.RLock()
    defer ks.mu.RUnlock()

    unlockedKey, found := ks.unlocked[a.Address]
    if !found {
        return nil, ErrLocked
    }
    // Sign the hash using plain ECDSA operations
    return crypto.Sign(hash, unlockedKey.PrivateKey)
}

// SignTx signs the given transaction with the requested account.
func (ks *KeyStore) SignTx(a accounts.Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
    // Look up the key to sign with and abort if it cannot be found
    ks.mu.RLock()
    defer ks.mu.RUnlock()

    unlockedKey, found := ks.unlocked[a.Address]
    if !found {
        return nil, ErrLocked
    }
    // Depending on the presence of the chain ID, sign with EIP155 or homestead
    if chainID != nil {
        return types.SignTx(tx, types.NewEIP155Signer(chainID), unlockedKey.PrivateKey)
    }
    return types.SignTx(tx, types.HomesteadSigner{}, unlockedKey.PrivateKey)
}

// SignHashWithPassphrase signs hash if the private key matching the given address
// can be decrypted with the given passphrase. The produced signature is in the
// [R || S || V] format where V is 0 or 1.
func (ks *KeyStore) SignHashWithPassphrase(a accounts.Account, passphrase string, hash []byte) (signature []byte, err error) {
    _, key, err := ks.getDecryptedKey(a, passphrase)
    if err != nil {
        return nil, err
    }
    defer zeroKey(key.PrivateKey)
    return crypto.Sign(hash, key.PrivateKey)
}

// SignTxWithPassphrase signs the transaction if the private key matching the
// given address can be decrypted with the given passphrase.
func (ks *KeyStore) SignTxWithPassphrase(a accounts.Account, passphrase string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
    _, key, err := ks.getDecryptedKey(a, passphrase)
    if err != nil {
        return nil, err
    }
    defer zeroKey(key.PrivateKey)

    // Depending on the presence of the chain ID, sign with EIP155 or homestead
    if chainID != nil {
        return types.SignTx(tx, types.NewEIP155Signer(chainID), key.PrivateKey)
    }
    return types.SignTx(tx, types.HomesteadSigner{}, key.PrivateKey)
}

// Unlock unlocks the given account indefinitely.
func (ks *KeyStore) Unlock(a accounts.Account, passphrase string) error {
    return ks.TimedUnlock(a, passphrase, 0)
}

// Lock removes the private key with the given address from memory.
func (ks *KeyStore) Lock(addr common.Address) error {
    ks.mu.Lock()
    if unl, found := ks.unlocked[addr]; found {
        ks.mu.Unlock()
        ks.expire(addr, unl, time.Duration(0)*time.Nanosecond)
    } else {
        ks.mu.Unlock()
    }
    return nil
}

// TimedUnlock unlocks the given account with the passphrase. The account
// stays unlocked for the duration of timeout. A timeout of 0 unlocks the account
// until the program exits. The account must match a unique key file.
//
// If the account address is already unlocked for a duration, TimedUnlock extends or
// shortens the active unlock timeout. If the address was previously unlocked
// indefinitely the timeout is not altered.
func (ks *KeyStore) TimedUnlock(a accounts.Account, passphrase string, timeout time.Duration) error {
    a, key, err := ks.getDecryptedKey(a, passphrase)
    if err != nil {
        return err
    }

    ks.mu.Lock()
    defer ks.mu.Unlock()
    u, found := ks.unlocked[a.Address]
    if found {
        if u.abort == nil {
            // The address was unlocked indefinitely, so unlocking
            // it with a timeout would be confusing.
            zeroKey(key.PrivateKey)
            return nil
        }
        // Terminate the expire goroutine and replace it below.
        close(u.abort)
    }
    if timeout > 0 {
        u = &unlocked{Key: key, abort: make(chan struct{})}
        go ks.expire(a.Address, u, timeout)
    } else {
        u = &unlocked{Key: key}
    }
    ks.unlocked[a.Address] = u
    return nil
}

// Find resolves the given account into a unique entry in the keystore.
func (ks *KeyStore) Find(a accounts.Account) (accounts.Account, error) {
    ks.cache.maybeReload()
    ks.cache.mu.Lock()
    a, err := ks.cache.find(a)
    ks.cache.mu.Unlock()
    return a, err
}

func (ks *KeyStore) getDecryptedKey(a accounts.Account, auth string) (accounts.Account, *Key, error) {
    a, err := ks.Find(a)
    if err != nil {
        return a, nil, err
    }
    key, err := ks.storage.GetKey(a.Address, a.URL.Path, auth)
    return a, key, err
}

func (ks *KeyStore) expire(addr common.Address, u *unlocked, timeout time.Duration) {
    t := time.NewTimer(timeout)
    defer t.Stop()
    select {
    case <-u.abort:
        // just quit
    case <-t.C:
        ks.mu.Lock()
        // only drop if it's still the same key instance that dropLater
        // was launched with. we can check that using pointer equality
        // because the map stores a new pointer every time the key is
        // unlocked.
        if ks.unlocked[addr] == u {
            zeroKey(u.PrivateKey)
            delete(ks.unlocked, addr)
        }
        ks.mu.Unlock()
    }
}

// NewAccount generates a new key and stores it into the key directory,
// encrypting it with the passphrase.
func (ks *KeyStore) NewAccount(passphrase string) (accounts.Account, error) {
    _, account, err := storeNewKey(ks.storage, crand.Reader, passphrase)
    if err != nil {
        return accounts.Account{}, err
    }
    // Add the account to the cache immediately rather
    // than waiting for file system notifications to pick it up.
    ks.cache.add(account)
    ks.refreshWallets()
    return account, nil
}

// Export exports as a JSON key, encrypted with newPassphrase.
func (ks *KeyStore) Export(a accounts.Account, passphrase, newPassphrase string) (keyJSON []byte, err error) {
    _, key, err := ks.getDecryptedKey(a, passphrase)
    if err != nil {
        return nil, err
    }
    var N, P int
    if store, ok := ks.storage.(*keyStorePassphrase); ok {
        N, P = store.scryptN, store.scryptP
    } else {
        N, P = StandardScryptN, StandardScryptP
    }
    return EncryptKey(key, newPassphrase, N, P)
}

// Import stores the given encrypted JSON key into the key directory.
func (ks *KeyStore) Import(keyJSON []byte, passphrase, newPassphrase string) (accounts.Account, error) {
    key, err := DecryptKey(keyJSON, passphrase)
    if key != nil && key.PrivateKey != nil {
        defer zeroKey(key.PrivateKey)
    }
    if err != nil {
        return accounts.Account{}, err
    }
    return ks.importKey(key, newPassphrase)
}

// ImportECDSA stores the given key into the key directory, encrypting it with the passphrase.
func (ks *KeyStore) ImportECDSA(priv *ecdsa.PrivateKey, passphrase string) (accounts.Account, error) {
    key := newKeyFromECDSA(priv)
    if ks.cache.hasAddress(key.Address) {
        return accounts.Account{}, fmt.Errorf("account already exists")
    }
    return ks.importKey(key, passphrase)
}

func (ks *KeyStore) importKey(key *Key, passphrase string) (accounts.Account, error) {
    a := accounts.Account{Address: key.Address, URL: accounts.URL{Scheme: KeyStoreScheme, Path: ks.storage.JoinPath(keyFileName(key.Address))}}
    if err := ks.storage.StoreKey(a.URL.Path, key, passphrase); err != nil {
        return accounts.Account{}, err
    }
    ks.cache.add(a)
    ks.refreshWallets()
    return a, nil
}

// Update changes the passphrase of an existing account.
func (ks *KeyStore) Update(a accounts.Account, passphrase, newPassphrase string) error {
    a, key, err := ks.getDecryptedKey(a, passphrase)
    if err != nil {
        return err
    }
    return ks.storage.StoreKey(a.URL.Path, key, newPassphrase)
}

// ImportPreSaleKey decrypts the given Ethereum presale wallet and stores
// a key file in the key directory. The key file is encrypted with the same passphrase.
func (ks *KeyStore) ImportPreSaleKey(keyJSON []byte, passphrase string) (accounts.Account, error) {
    a, _, err := importPreSaleKey(ks.storage, keyJSON, passphrase)
    if err != nil {
        return a, err
    }
    ks.cache.add(a)
    ks.refreshWallets()
    return a, nil
}

// zeroKey zeroes a private key in memory.
func zeroKey(k *ecdsa.PrivateKey) {
    b := k.D.Bits()
    for i := range b {
        b[i] = 0
    }
}