Implement walletpassphrasechange RPC call.

Closes #62.

account.go

@@ -130,7 +130,7 @@ func (a *Account) Lock() error {
 }
 
 // Unlock unlocks the underlying wallet for an account.
-func (a *Account) Unlock(passphrase []byte, timeout int64) error {
+func (a *Account) Unlock(passphrase []byte) error {
 	a.mtx.Lock()
 	defer a.mtx.Unlock()
 

accountstore.go

@@ -226,6 +226,75 @@ func (store *AccountStore) CreateEncryptedWallet(name, desc string, passphrase [
 	return nil
 }
 
+// ChangePassphrase unlocks all account wallets with the old
+// passphrase, and re-encrypts each using the new passphrase.
+func (store *AccountStore) ChangePassphrase(old, new []byte) error {
+	store.RLock()
+	defer store.RUnlock()
+
+	// Check that each account can be unlocked with the old passphrase.
+	// Each's account's wallet mutex is unlocked with a defer so they
+	// will be held for the duration of this function.  This prevents
+	// a wallet from being locked after some timeout after a RPC call
+	// to walletpassphrase.
+	for _, a := range store.accounts {
+		a.mtx.Lock()
+		defer a.mtx.Unlock()
+
+		if locked := a.Wallet.IsLocked(); !locked {
+			if err := a.Wallet.Lock(); err != nil {
+				return err
+			}
+		}
+
+		if err := a.Wallet.Unlock(old); err != nil {
+			return err
+		}
+		defer a.Wallet.Lock()
+	}
+
+	// Change passphrase for each unlocked wallet.
+	for _, a := range store.accounts {
+		if err := a.Wallet.ChangePassphrase(new); err != nil {
+			return err
+		}
+		a.dirty = true
+	}
+
+	// Immediately write out to disk. Create a new temporary network
+	// directory to write to, write all account files there, then move
+	// to the real network directory.  This provides an safe
+	// replacement of all account files and ensures that all wallets
+	// are using either the old or new passphrase, but never two wallets
+	// with different passphrases.
+	netDir := networkDir(cfg.Net())
+	tmpNetDir := tmpNetworkDir(cfg.Net())
+	for _, a := range store.accounts {
+		// Writer locks must be held for the tx and utxo stores as well,
+		// to unset the dirty flag.
+		a.UtxoStore.Lock()
+		defer a.UtxoStore.Unlock()
+		a.TxStore.Lock()
+		defer a.TxStore.Unlock()
+
+		if err := a.writeAllToFreshDir(tmpNetDir); err != nil {
+			return err
+		}
+	}
+
+	// This is technically NOT an atomic operation, but at startup, if the
+	// network directory is missing but the temporary network directory
+	// exists, the temporary is moved before accounts are opened.
+	if err := os.RemoveAll(netDir); err != nil {
+		return err
+	}
+	if err := Rename(tmpNetDir, netDir); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 // DumpKeys returns all WIF-encoded private keys associated with all
 // accounts. All wallets must be unlocked for this operation to succeed.
 func (store *AccountStore) DumpKeys() ([]string, error) {

cmd.go

@@ -248,6 +248,21 @@ func main() {
 
 // OpenAccounts attempts to open all saved accounts.
 func OpenAccounts() {
+	// If the network (account) directory is missing, but the temporary
+	// directory exists, move it.  This is unlikely to happen, but possible,
+	// if writing out every account file at once to a tmp directory (as is
+	// done for changing a wallet passphrase) and btcwallet closes after
+	// removing the network directory but before renaming the temporary
+	// directory.
+	netDir := networkDir(cfg.Net())
+	tmpNetDir := tmpNetworkDir(cfg.Net())
+	if !fileExists(netDir) && fileExists(tmpNetDir) {
+		if err := Rename(tmpNetDir, netDir); err != nil {
+			log.Errorf("Cannot move temporary network dir: %v", err)
+			return
+		}
+	}
+
 	// The default account must exist, or btcwallet acts as if no
 	// wallets/accounts have been created yet.
 	if err := accountstore.OpenAccount("", cfg); err != nil {
@@ -264,7 +279,7 @@ func OpenAccounts() {
 	// Read all filenames in the account directory, and look for any
 	// filenames matching '*-wallet.bin'.  These are wallets for
 	// additional saved accounts.
-	accountDir, err := os.Open(networkDir(cfg.Net()))
+	accountDir, err := os.Open(netDir)
 	if err != nil {
 		// Can't continue.
 		log.Errorf("Unable to open account directory: %v", err)

cmdmgr.go

@@ -32,51 +32,51 @@ type cmdHandler func(btcjson.Cmd) (interface{}, *btcjson.Error)
 
 var rpcHandlers = map[string]cmdHandler{
 	// Standard bitcoind methods (implemented)
-	"dumpprivkey":           DumpPrivKey,
-	"getaccount":            GetAccount,
-	"getaccountaddress":     GetAccountAddress,
-	"getaddressesbyaccount": GetAddressesByAccount,
-	"getbalance":            GetBalance,
-	"getnewaddress":         GetNewAddress,
-	"importprivkey":         ImportPrivKey,
-	"keypoolrefill":         KeypoolRefill,
-	"listaccounts":          ListAccounts,
-	"listtransactions":      ListTransactions,
-	"sendfrom":              SendFrom,
-	"sendmany":              SendMany,
-	"settxfee":              SetTxFee,
-	"walletlock":            WalletLock,
-	"walletpassphrase":      WalletPassphrase,
+	"dumpprivkey":            DumpPrivKey,
+	"getaccount":             GetAccount,
+	"getaccountaddress":      GetAccountAddress,
+	"getaddressesbyaccount":  GetAddressesByAccount,
+	"getbalance":             GetBalance,
+	"getnewaddress":          GetNewAddress,
+	"importprivkey":          ImportPrivKey,
+	"keypoolrefill":          KeypoolRefill,
+	"listaccounts":           ListAccounts,
+	"listtransactions":       ListTransactions,
+	"sendfrom":               SendFrom,
+	"sendmany":               SendMany,
+	"settxfee":               SetTxFee,
+	"walletlock":             WalletLock,
+	"walletpassphrase":       WalletPassphrase,
+	"walletpassphrasechange": WalletPassphraseChange,
 
 	// Standard bitcoind methods (currently unimplemented)
-	"addmultisigaddress":     Unimplemented,
-	"backupwallet":           Unimplemented,
-	"createmultisig":         Unimplemented,
-	"dumpwallet":             Unimplemented,
-	"getblocktemplate":       Unimplemented,
-	"getrawchangeaddress":    Unimplemented,
-	"getreceivedbyaccount":   Unimplemented,
-	"getreceivedbyaddress":   Unimplemented,
-	"gettransaction":         Unimplemented,
-	"gettxout":               Unimplemented,
-	"gettxoutsetinfo":        Unimplemented,
-	"getwork":                Unimplemented,
-	"importwallet":           Unimplemented,
-	"listaddressgroupings":   Unimplemented,
-	"listlockunspent":        Unimplemented,
-	"listreceivedbyaccount":  Unimplemented,
-	"listsinceblock":         Unimplemented,
-	"listreceivedbyaddress":  Unimplemented,
-	"listunspent":            Unimplemented,
-	"lockunspent":            Unimplemented,
-	"move":                   Unimplemented,
-	"sendtoaddress":          Unimplemented,
-	"setaccount":             Unimplemented,
-	"signmessage":            Unimplemented,
-	"signrawtransaction":     Unimplemented,
-	"validateaddress":        Unimplemented,
-	"verifymessage":          Unimplemented,
-	"walletpassphrasechange": Unimplemented,
+	"addmultisigaddress":    Unimplemented,
+	"backupwallet":          Unimplemented,
+	"createmultisig":        Unimplemented,
+	"dumpwallet":            Unimplemented,
+	"getblocktemplate":      Unimplemented,
+	"getrawchangeaddress":   Unimplemented,
+	"getreceivedbyaccount":  Unimplemented,
+	"getreceivedbyaddress":  Unimplemented,
+	"gettransaction":        Unimplemented,
+	"gettxout":              Unimplemented,
+	"gettxoutsetinfo":       Unimplemented,
+	"getwork":               Unimplemented,
+	"importwallet":          Unimplemented,
+	"listaddressgroupings":  Unimplemented,
+	"listlockunspent":       Unimplemented,
+	"listreceivedbyaccount": Unimplemented,
+	"listsinceblock":        Unimplemented,
+	"listreceivedbyaddress": Unimplemented,
+	"listunspent":           Unimplemented,
+	"lockunspent":           Unimplemented,
+	"move":                  Unimplemented,
+	"sendtoaddress":         Unimplemented,
+	"setaccount":            Unimplemented,
+	"signmessage":           Unimplemented,
+	"signrawtransaction":    Unimplemented,
+	"validateaddress":       Unimplemented,
+	"verifymessage":         Unimplemented,
 
 	// Standard bitcoind methods which won't be implemented by btcwallet.
 	"encryptwallet": Unsupported,
@@ -1277,7 +1277,7 @@ func WalletPassphrase(icmd btcjson.Cmd) (interface{}, *btcjson.Error) {
 		return nil, &e
 	}
 
-	switch err := a.Unlock([]byte(cmd.Passphrase), cmd.Timeout); err {
+	switch err := a.Unlock([]byte(cmd.Passphrase)); err {
 	case nil:
 		go func(timeout int64) {
 			time.Sleep(time.Second * time.Duration(timeout))
@@ -1293,6 +1293,37 @@ func WalletPassphrase(icmd btcjson.Cmd) (interface{}, *btcjson.Error) {
 	}
 }
 
+// WalletPassphraseChange responds to the walletpassphrasechange request
+// by unlocking all accounts with the provided old passphrase, and
+// re-encrypting each private key with an AES key derived from the new
+// passphrase.
+//
+// If the old passphrase is correct and the passphrase is changed, all
+// wallets will be immediately locked.
+func WalletPassphraseChange(icmd btcjson.Cmd) (interface{}, *btcjson.Error) {
+	cmd, ok := icmd.(*btcjson.WalletPassphraseChangeCmd)
+	if !ok {
+		return nil, &btcjson.ErrInternal
+	}
+
+	err := accountstore.ChangePassphrase([]byte(cmd.OldPassphrase),
+		[]byte(cmd.NewPassphrase))
+	switch err {
+	case nil:
+		return nil, nil
+
+	case wallet.ErrWrongPassphrase:
+		return nil, &btcjson.ErrWalletPassphraseIncorrect
+
+	default: // all other non-nil errors
+		e := btcjson.Error{
+			Code:    btcjson.ErrWallet.Code,
+			Message: err.Error(),
+		}
+		return nil, &e
+	}
+}
+
 // AccountNtfn is a struct for marshalling any generic notification
 // about a account for a wallet frontend.
 //

disksync.go

@@ -36,8 +36,8 @@ var (
 	}
 )
 
-// networkDir returns the base directory name for the bitcoin network
-// net.
+// networkDir returns the directory name of a network directory to hold account
+// files.
 func networkDir(net btcwire.BitcoinNet) string {
 	var netname string
 	if net == btcwire.MainNet {
@@ -48,6 +48,11 @@ func networkDir(net btcwire.BitcoinNet) string {
 	return filepath.Join(cfg.DataDir, netname)
 }
 
+// tmpNetworkDir returns the temporary directory name for a given network.
+func tmpNetworkDir(net btcwire.BitcoinNet) string {
+	return networkDir(net) + "_tmp"
+}
+
 // checkCreateDir checks that the path exists and is a directory.
 // If path does not exist, it is created.
 func checkCreateDir(path string) error {
@@ -109,6 +114,82 @@ func DirtyAccountSyncer() {
 	}
 }
 
+// freshDir creates a new directory specified by path if it does not
+// exist.  If the directory already exists, all files contained in the
+// directory are removed.
+func freshDir(path string) error {
+	if err := checkCreateDir(path); err != nil {
+		return err
+	}
+
+	// Remove all files in the directory.
+	fd, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer fd.Close()
+	names, err := fd.Readdirnames(0)
+	if err != nil {
+		return err
+	}
+	for _, name := range names {
+		if err := os.RemoveAll(name); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// writeAllToFreshDir writes all account files to the specified directory.
+// If dir already exists, any old files are removed.  If dir does not
+// exist, it is created.
+//
+// It is a runtime error to call this function while not holding each
+// wallet, tx store, and utxo store writer lock.
+func (a *Account) writeAllToFreshDir(dir string) error {
+	if err := freshDir(dir); err != nil {
+		return err
+	}
+
+	wfilepath := accountFilename("wallet.bin", a.name, dir)
+	txfilepath := accountFilename("tx.bin", a.name, dir)
+	utxofilepath := accountFilename("utxo.bin", a.name, dir)
+
+	wfile, err := os.Create(wfilepath)
+	if err != nil {
+		return err
+	}
+	defer wfile.Close()
+	txfile, err := os.Create(txfilepath)
+	if err != nil {
+		return err
+	}
+	defer txfile.Close()
+	utxofile, err := os.Create(utxofilepath)
+	if err != nil {
+		return err
+	}
+	defer utxofile.Close()
+
+	if _, err := a.Wallet.WriteTo(wfile); err != nil {
+		return err
+	}
+	a.dirty = false
+
+	if _, err := a.TxStore.s.WriteTo(txfile); err != nil {
+		return err
+	}
+	a.TxStore.dirty = false
+
+	if _, err := a.UtxoStore.s.WriteTo(utxofile); err != nil {
+		return err
+	}
+	a.UtxoStore.dirty = false
+
+	return nil
+}
+
 // writeDirtyToDisk checks for the dirty flag on an account's wallet,
 // txstore, and utxostore, writing them to disk if any are dirty.
 func (a *Account) writeDirtyToDisk() error {

tx/tx.go

@@ -109,6 +109,7 @@ type Tx interface {
 	ReadFromVersion(uint32, io.Reader) (int64, error)
 	TxInfo(string, int32, btcwire.BitcoinNet) []map[string]interface{}
 }
+
 // TxStore is a slice holding RecvTx and SendTx pointers.
 type TxStore []Tx
 

updates.go

@@ -75,6 +75,22 @@ func updateOldFileLocations() {
 		os.Exit(1)
 	}
 
+	acctsExist := false
+	for i := range fi {
+		// Ignore non-directories.
+		if !fi[i].IsDir() {
+			continue
+		}
+
+		if strings.HasPrefix(fi[i].Name(), "btcwallet") {
+			acctsExist = true
+			break
+		}
+	}
+	if !acctsExist {
+		return
+	}
+
 	// Create testnet directory, if it doesn't already exist.
 	netdir := filepath.Join(cfg.DataDir, "testnet")
 	if err := checkCreateDir(netdir); err != nil {

wallet/wallet.go

@@ -61,6 +61,7 @@ var (
 	ErrWalletDoesNotExist   = errors.New("non-existant wallet")
 	ErrWalletIsWatchingOnly = errors.New("wallet is watching-only")
 	ErrWalletLocked         = errors.New("wallet is locked")
+	ErrWrongPassphrase      = errors.New("wrong passphrase")
 )
 
 var (
@@ -845,6 +846,37 @@ func (w *Wallet) Passphrase() ([]byte, error) {
 	return nil, ErrWalletLocked
 }
 
+// ChangePassphrase creates a new AES key from a new passphrase and
+// re-encrypts all encrypted private keys with the new key.
+func (w *Wallet) ChangePassphrase(new []byte) error {
+	if w.flags.watchingOnly {
+		return ErrWalletIsWatchingOnly
+	}
+
+	if len(w.secret) != 32 {
+		return ErrWalletLocked
+	}
+
+	oldkey := w.secret
+	newkey := Key(new, &w.kdfParams)
+
+	for _, a := range w.addrMap {
+		if err := a.changeEncryptionKey(oldkey, newkey); err != nil {
+			return err
+		}
+	}
+
+	// zero old secrets.
+	zero(w.passphrase)
+	zero(w.secret)
+
+	// Save new secrets.
+	w.passphrase = new
+	w.secret = newkey
+
+	return nil
+}
+
 func zero(b []byte) {
 	for i := range b {
 		b[i] = 0
@@ -2151,7 +2183,7 @@ func (a *btcAddress) unlock(key []byte) (privKeyCT []byte, err error) {
 	}
 	x, y := btcec.S256().ScalarBaseMult(privkey)
 	if x.Cmp(pubKey.X) != 0 || y.Cmp(pubKey.Y) != 0 {
-		return nil, errors.New("decryption failed")
+		return nil, ErrWrongPassphrase
 	}
 
 	privkeyCopy := make([]byte, 32)
@@ -2160,9 +2192,36 @@ func (a *btcAddress) unlock(key []byte) (privKeyCT []byte, err error) {
 	return privkeyCopy, nil
 }
 
-// TODO(jrick)
+// changeEncryptionKey re-encrypts the private keys for an address
+// with a new AES encryption key.  oldkey must be the old AES encryption key
+// and is used to decrypt the private key.
 func (a *btcAddress) changeEncryptionKey(oldkey, newkey []byte) error {
-	return errors.New("unimplemented")
+	// Address must have a private key and be encrypted to continue.
+	if !a.flags.hasPrivKey {
+		return errors.New("no private key")
+	}
+	if !a.flags.encrypted {
+		return errors.New("address is not encrypted")
+	}
+
+	privKeyCT, err := a.unlock(oldkey)
+	if err != nil {
+		return err
+	}
+
+	aesBlockEncrypter, err := aes.NewCipher(newkey)
+	if err != nil {
+		return err
+	}
+	newIV := make([]byte, len(a.initVector))
+	if _, err := rand.Read(newIV); err != nil {
+		return err
+	}
+	copy(a.initVector[:], newIV)
+	aesEncrypter := cipher.NewCFBEncrypter(aesBlockEncrypter, a.initVector[:])
+	aesEncrypter.XORKeyStream(a.privKey[:], privKeyCT)
+
+	return nil
 }
 
 // address returns a btcutil.AddressPubKeyHash for a btcAddress.

wallet/wallet_test.go

@@ -667,3 +667,78 @@ func TestWatchingWalletExport(t *testing.T) {
 		return
 	}
 }
+
+func TestChangePassphrase(t *testing.T) {
+	const keypoolSize = 10
+	createdAt := &BlockStamp{}
+	w, err := NewWallet("banana wallet", "A wallet for testing.",
+		[]byte("banana"), btcwire.MainNet, createdAt, keypoolSize)
+	if err != nil {
+		t.Error("Error creating new wallet: " + err.Error())
+		return
+	}
+
+	// Changing the passphrase with a locked wallet must fail with ErrWalletLocked.
+	if err := w.ChangePassphrase([]byte("potato")); err != ErrWalletLocked {
+		t.Errorf("Changing passphrase on a locked wallet did not fail correctly: %v", err)
+		return
+	}
+
+	// Unlock wallet so the passphrase can be changed.
+	if err := w.Unlock([]byte("banana")); err != nil {
+		t.Errorf("Cannot unlock: %v", err)
+		return
+	}
+
+	// Get root address and its private key.  This is compared to the private
+	// key post passphrase change.
+	rootAddr := w.LastChainedAddress()
+	rootPrivKey, err := w.AddressKey(rootAddr)
+	if err != nil {
+		t.Errorf("Cannot get root address' private key: %v", err)
+		return
+	}
+
+	// Change passphrase.
+	if err := w.ChangePassphrase([]byte("potato")); err != nil {
+		t.Errorf("Changing passhprase failed: %v", err)
+		return
+	}
+
+	// Wallet should still be unlocked.
+	if w.IsLocked() {
+		t.Errorf("Wallet should be unlocked after passphrase change.")
+		return
+	}
+
+	// Lock it.
+	if err := w.Lock(); err != nil {
+		t.Errorf("Cannot lock wallet after passphrase change: %v", err)
+		return
+	}
+
+	// Unlock with old passphrase.  This must fail with ErrWrongPassphrase.
+	if err := w.Unlock([]byte("banana")); err != ErrWrongPassphrase {
+		t.Errorf("Unlocking with old passphrases did not fail correctly: %v", err)
+		return
+	}
+
+	// Unlock with new passphrase.  This must succeed.
+	if err := w.Unlock([]byte("potato")); err != nil {
+		t.Errorf("Unlocking with new passphrase failed: %v", err)
+		return
+	}
+
+	// Get root address' private key again.
+	rootPrivKey2, err := w.AddressKey(rootAddr)
+	if err != nil {
+		t.Errorf("Cannot get root address' private key after passphrase change: %v", err)
+		return
+	}
+
+	// Private keys must match.
+	if !reflect.DeepEqual(rootPrivKey, rootPrivKey2) {
+		t.Errorf("Private keys before and after unlock differ.")
+		return
+	}
+}