We build too many walls and not enough bridges

pkg/pmapi/passwords.go

@@ -0,0 +1,47 @@
+// Copyright (c) 2020 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ProtonMail Bridge 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package pmapi
+
+import (
+	"encoding/base64"
+	"errors"
+
+	"github.com/jameskeane/bcrypt"
+)
+
+func HashMailboxPassword(password, keySalt string) (hashedPassword string, err error) {
+	if keySalt == "" {
+		hashedPassword = password
+		return
+	}
+	decodedSalt, err := base64.StdEncoding.DecodeString(keySalt)
+	if err != nil {
+		return
+	}
+	encodedSalt := base64.NewEncoding("./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789").WithPadding(base64.NoPadding).EncodeToString(decodedSalt)
+	hashResult, err := bcrypt.Hash(password, "$2y$10$"+encodedSalt)
+	if err != nil {
+		return
+	}
+	if len(hashResult) != 60 {
+		err = errors.New("pmapi: invalid mailbox password hash")
+		return
+	}
+	hashedPassword = hashResult[len(hashResult)-31:]
+	return
+}