keys: Keybase.Update no longer asks for newpass if oldpass is incorrect

Achieved by refactoring the parameter newpass as follows:

* (newpass string) -> (getNewpass func() (string, error))

Closes #1629

crypto/keys/keybase.go

@@ -330,8 +330,9 @@ func (kb dbKeybase) Delete(name, passphrase string) error {
 // encrypted.
 //
 // oldpass must be the current passphrase used for encryption,
-// newpass will be the only valid passphrase from this time forward.
-func (kb dbKeybase) Update(name, oldpass, newpass string) error {
+// getNewpass is a function to get the passphrase to permanently replace
+// the current passphrase
+func (kb dbKeybase) Update(name, oldpass string, getNewpass func() (string, error)) error {
 	info, err := kb.Get(name)
 	if err != nil {
 		return err
@@ -343,6 +344,10 @@ func (kb dbKeybase) Update(name, oldpass, newpass string) error {
 		if err != nil {
 			return err
 		}
+		newpass, err := getNewpass()
+		if err != nil {
+			return err
+		}
 		kb.writeLocalKey(key, name, newpass)
 		return nil
 	default:

crypto/keys/keybase_test.go

@@ -167,9 +167,10 @@ func TestSignVerify(t *testing.T) {
 }
 
 func assertPassword(t *testing.T, cstore Keybase, name, pass, badpass string) {
-	err := cstore.Update(name, badpass, pass)
+	getNewpass := func() (string, error) { return pass, nil }
+	err := cstore.Update(name, badpass, getNewpass)
 	require.NotNil(t, err)
-	err = cstore.Update(name, pass, pass)
+	err = cstore.Update(name, pass, getNewpass)
 	require.Nil(t, err, "%+v", err)
 }
 
@@ -265,12 +266,13 @@ func TestAdvancedKeyManagement(t *testing.T) {
 	assertPassword(t, cstore, n1, p1, p2)
 
 	// update password requires the existing password
-	err = cstore.Update(n1, "jkkgkg", p2)
+	getNewpass := func() (string, error) { return p2, nil }
+	err = cstore.Update(n1, "jkkgkg", getNewpass)
 	require.NotNil(t, err)
 	assertPassword(t, cstore, n1, p1, p2)
 
 	// then it changes the password when correct
-	err = cstore.Update(n1, p1, p2)
+	err = cstore.Update(n1, p1, getNewpass)
 	require.NoError(t, err)
 	// p2 is now the proper one!
 	assertPassword(t, cstore, n1, p2, p1)

crypto/keys/types.go

@@ -34,7 +34,7 @@ type Keybase interface {
 	CreateOffline(name string, pubkey crypto.PubKey) (info Info, err error)
 
 	// The following operations will *only* work on locally-stored keys
-	Update(name, oldpass, newpass string) error
+	Update(name, oldpass string, getNewpass func() (string, error)) error
 	Import(name string, armor string) (err error)
 	ImportPubKey(name string, armor string) (err error)
 	Export(name string) (armor string, err error)