path: root/accounts/account_manager.go

// Copyright 2015 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 accounts 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 accounts

import (
    "crypto/ecdsa"
    crand "crypto/rand"
    "encoding/json"
    "errors"
    "fmt"
    "os"
    "path/filepath"
    "runtime"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto"
)

var (
    ErrLocked  = errors.New("account is locked")
    ErrNoMatch = errors.New("no key for given address or file")
    ErrDecrypt = errors.New("could not decrypt key with given passphrase")
)

// Account represents a stored key.
// When used as an argument, it selects a unique key file to act on.
type Account struct {
    Address common.Address // Ethereum account address derived from the key

    // File contains the key file name.
    // When Acccount is used as an argument to select a key, File can be left blank to
    // select just by address or set to the basename or absolute path of a file in the key
    // directory. Accounts returned by Manager will always contain an absolute path.
    File string
}

func (acc *Account) MarshalJSON() ([]byte, error) {
    return []byte(`"` + acc.Address.Hex() + `"`), nil
}

func (acc *Account) UnmarshalJSON(raw []byte) error {
    return json.Unmarshal(raw, &acc.Address)
}

// Manager manages a key storage directory on disk.
type Manager struct {
    cache    *addrCache
    keyStore keyStore
    mu       sync.RWMutex
    unlocked map[common.Address]*unlocked
}

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

// NewManager creates a manager for the given directory.
func NewManager(keydir string, scryptN, scryptP int) *Manager {
    keydir, _ = filepath.Abs(keydir)
    am := &Manager{keyStore: &keyStorePassphrase{keydir, scryptN, scryptP}}
    am.init(keydir)
    return am
}

// NewPlaintextManager creates a manager for the given directory.
// Deprecated: Use NewManager.
func NewPlaintextManager(keydir string) *Manager {
    keydir, _ = filepath.Abs(keydir)
    am := &Manager{keyStore: &keyStorePlain{keydir}}
    am.init(keydir)
    return am
}

func (am *Manager) init(keydir string) {
    am.unlocked = make(map[common.Address]*unlocked)
    am.cache = newAddrCache(keydir)
    // TODO: In order for this finalizer to work, there must be no references
    // to am. addrCache doesn't keep a reference but unlocked keys do,
    // so the finalizer will not trigger until all timed unlocks have expired.
    runtime.SetFinalizer(am, func(m *Manager) {
        m.cache.close()
    })
}

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

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

// DeleteAccount deletes the key matched by account if the passphrase is correct.
// If a contains no filename, the address must match a unique key.
func (am *Manager) DeleteAccount(a 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 := am.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.File)
    if err == nil {
        am.cache.delete(a)
    }
    return err
}

// Sign 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 (am *Manager) Sign(addr common.Address, hash []byte) ([]byte, error) {
    am.mu.RLock()
    defer am.mu.RUnlock()

    unlockedKey, found := am.unlocked[addr]
    if !found {
        return nil, ErrLocked
    }
    return crypto.Sign(hash, unlockedKey.PrivateKey)
}

// SignWithPassphrase 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 (am *Manager) SignWithPassphrase(a Account, passphrase string, hash []byte) (signature []byte, err error) {
    _, key, err := am.getDecryptedKey(a, passphrase)
    if err != nil {
        return nil, err
    }
    defer zeroKey(key.PrivateKey)
    return crypto.Sign(hash, key.PrivateKey)
}

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

// Lock removes the private key with the given address from memory.
func (am *Manager) Lock(addr common.Address) error {
    am.mu.Lock()
    if unl, found := am.unlocked[addr]; found {
        am.mu.Unlock()
        am.expire(addr, unl, time.Duration(0)*time.Nanosecond)
    } else {
        am.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 (am *Manager) TimedUnlock(a Account, passphrase string, timeout time.Duration) error {
    a, key, err := am.getDecryptedKey(a, passphrase)
    if err != nil {
        return err
    }

    am.mu.Lock()
    defer am.mu.Unlock()
    u, found := am.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
        } else {
            // Terminate the expire goroutine and replace it below.
            close(u.abort)
        }
    }
    if timeout > 0 {
        u = &unlocked{Key: key, abort: make(chan struct{})}
        go am.expire(a.Address, u, timeout)
    } else {
        u = &unlocked{Key: key}
    }
    am.unlocked[a.Address] = u
    return nil
}

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

func (am *Manager) getDecryptedKey(a Account, auth string) (Account, *Key, error) {
    a, err := am.Find(a)
    if err != nil {
        return a, nil, err
    }
    key, err := am.keyStore.GetKey(a.Address, a.File, auth)
    return a, key, err
}

func (am *Manager) 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:
        am.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 am.unlocked[addr] == u {
            zeroKey(u.PrivateKey)
            delete(am.unlocked, addr)
        }
        am.mu.Unlock()
    }
}

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

// AccountByIndex returns the ith account.
func (am *Manager) AccountByIndex(i int) (Account, error) {
    accounts := am.Accounts()
    if i < 0 || i >= len(accounts) {
        return Account{}, fmt.Errorf("account index %d out of range [0, %d]", i, len(accounts)-1)
    }
    return accounts[i], nil
}

// Export exports as a JSON key, encrypted with newPassphrase.
func (am *Manager) Export(a Account, passphrase, newPassphrase string) (keyJSON []byte, err error) {
    _, key, err := am.getDecryptedKey(a, passphrase)
    if err != nil {
        return nil, err
    }
    var N, P int
    if store, ok := am.keyStore.(*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 (am *Manager) Import(keyJSON []byte, passphrase, newPassphrase string) (Account, error) {
    key, err := DecryptKey(keyJSON, passphrase)
    if key != nil && key.PrivateKey != nil {
        defer zeroKey(key.PrivateKey)
    }
    if err != nil {
        return Account{}, err
    }
    return am.importKey(key, newPassphrase)
}

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

    return am.importKey(key, passphrase)
}

func (am *Manager) importKey(key *Key, passphrase string) (Account, error) {
    a := Account{Address: key.Address, File: am.keyStore.JoinPath(keyFileName(key.Address))}
    if err := am.keyStore.StoreKey(a.File, key, passphrase); err != nil {
        return Account{}, err
    }
    am.cache.add(a)
    return a, nil
}

// Update changes the passphrase of an existing account.
func (am *Manager) Update(a Account, passphrase, newPassphrase string) error {
    a, key, err := am.getDecryptedKey(a, passphrase)
    if err != nil {
        return err
    }
    return am.keyStore.StoreKey(a.File, 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 (am *Manager) ImportPreSaleKey(keyJSON []byte, passphrase string) (Account, error) {
    a, _, err := importPreSaleKey(am.keyStore, keyJSON, passphrase)
    if err != nil {
        return a, err
    }
    am.cache.add(a)
    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
    }
}