Move attachment/websocket [en|de]cryption to libtextsecure

Gruntfile.js

@@ -92,6 +92,7 @@ module.exports = function(grunt) {
           'libtextsecure/axolotl_wrapper.js',
           'libtextsecure/libaxolotl_concat.js',
 
+          'libtextsecure/crypto.js',
           'libtextsecure/storage.js',
           'libtextsecure/storage/devices.js',
           'libtextsecure/protobufs.js',

js/background.js

@@ -37,7 +37,7 @@
         new WebSocketResource(socket, function(request) {
             // TODO: handle different types of requests. for now we only expect
             // PUT /messages <encrypted IncomingPushMessageSignal>
-            textsecure.protocol.decryptWebsocketMessage(request.body).then(function(plaintext) {
+            textsecure.crypto.decryptWebsocketMessage(request.body).then(function(plaintext) {
                 var proto = textsecure.protobuf.IncomingPushMessageSignal.decode(plaintext);
                 // After this point, decoding errors are not the server's
                 // fault, and we should handle them gracefully and tell the

libaxolotl/crypto.js

@@ -17,7 +17,7 @@
     window.axolotl = window.axolotl || {};
 
     /*
-     *  textsecure.crypto
+     *  axolotl.crypto
      *    glues together various implementations into a single interface
      *    for all low-level crypto operations,
      */

libaxolotl/protocol.js

@@ -527,58 +527,6 @@ window.textsecure.protocol = function() {
         });
     }
 
-    // Decrypts message into a raw string
-    self.decryptWebsocketMessage = function(message) {
-        var signaling_key = textsecure.storage.getEncrypted("signaling_key"); //TODO: in crypto_storage
-        var aes_key = toArrayBuffer(signaling_key.substring(0, 32));
-        var mac_key = toArrayBuffer(signaling_key.substring(32, 32 + 20));
-
-        var decodedMessage = message.toArrayBuffer();
-        if (new Uint8Array(decodedMessage)[0] != 1)
-            throw new Error("Got bad version number: " + decodedMessage[0]);
-
-        var iv = decodedMessage.slice(1, 1 + 16);
-        var ciphertext = decodedMessage.slice(1 + 16, decodedMessage.byteLength - 10);
-        var ivAndCiphertext = decodedMessage.slice(0, decodedMessage.byteLength - 10);
-        var mac = decodedMessage.slice(decodedMessage.byteLength - 10, decodedMessage.byteLength);
-
-        return verifyMAC(ivAndCiphertext, mac_key, mac).then(function() {
-            return window.axolotl.crypto.decrypt(aes_key, ciphertext, iv);
-        });
-    };
-
-    self.decryptAttachment = function(encryptedBin, keys) {
-        var aes_key = keys.slice(0, 32);
-        var mac_key = keys.slice(32, 64);
-
-        var iv = encryptedBin.slice(0, 16);
-        var ciphertext = encryptedBin.slice(16, encryptedBin.byteLength - 32);
-        var ivAndCiphertext = encryptedBin.slice(0, encryptedBin.byteLength - 32);
-        var mac = encryptedBin.slice(encryptedBin.byteLength - 32, encryptedBin.byteLength);
-
-        return verifyMAC(ivAndCiphertext, mac_key, mac).then(function() {
-            return window.axolotl.crypto.decrypt(aes_key, ciphertext, iv);
-        });
-    };
-
-    self.encryptAttachment = function(plaintext, keys, iv) {
-        var aes_key = keys.slice(0, 32);
-        var mac_key = keys.slice(32, 64);
-
-        return window.axolotl.crypto.encrypt(aes_key, plaintext, iv).then(function(ciphertext) {
-            var ivAndCiphertext = new Uint8Array(16 + ciphertext.byteLength);
-            ivAndCiphertext.set(new Uint8Array(iv));
-            ivAndCiphertext.set(new Uint8Array(ciphertext), 16);
-
-            return axolotl.crypto.sign(mac_key, ivAndCiphertext.buffer).then(function(mac) {
-                var encryptedBin = new Uint8Array(16 + ciphertext.byteLength + 32);
-                encryptedBin.set(ivAndCiphertext);
-                encryptedBin.set(new Uint8Array(mac), 16 + ciphertext.byteLength);
-                return encryptedBin.buffer;
-            });
-        });
-    };
-
     // return Promise(encoded [PreKey]WhisperMessage)
     self.encryptMessageFor = function(deviceObject, pushMessageContent) {
         var session = crypto_storage.getOpenSession(deviceObject.encodedNumber);

libtextsecure/crypto.js

@@ -0,0 +1,83 @@
+/* vim: ts=4:sw=4:expandtab
+ *
+ * This program 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.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+;(function(){
+    'use strict';
+
+    // Various wrappers around low-level crypto operation for specific functions
+
+    var verifyMAC = function(data, key, mac) {
+        return axolotl.crypto.sign(key, data).then(function(calculated_mac) {
+            if (!isEqual(calculated_mac, mac, true))
+                throw new Error("Bad MAC");
+        });
+    }
+
+    window.textsecure = window.textsecure || {};
+    window.textsecure.crypto = {
+        // Decrypts message into a raw string
+        decryptWebsocketMessage: function(message) {
+            var signaling_key = axolotl.api.storage.get("signaling_key"); //TODO: in crypto_storage
+            var aes_key = toArrayBuffer(signaling_key.substring(0, 32));
+            var mac_key = toArrayBuffer(signaling_key.substring(32, 32 + 20));
+
+            var decodedMessage = message.toArrayBuffer();
+            if (new Uint8Array(decodedMessage)[0] != 1)
+                throw new Error("Got bad version number: " + decodedMessage[0]);
+
+            var iv = decodedMessage.slice(1, 1 + 16);
+            var ciphertext = decodedMessage.slice(1 + 16, decodedMessage.byteLength - 10);
+            var ivAndCiphertext = decodedMessage.slice(0, decodedMessage.byteLength - 10);
+            var mac = decodedMessage.slice(decodedMessage.byteLength - 10, decodedMessage.byteLength);
+
+            return verifyMAC(ivAndCiphertext, mac_key, mac).then(function() {
+                return window.axolotl.crypto.decrypt(aes_key, ciphertext, iv);
+            });
+        },
+
+        decryptAttachment: function(encryptedBin, keys) {
+            var aes_key = keys.slice(0, 32);
+            var mac_key = keys.slice(32, 64);
+
+            var iv = encryptedBin.slice(0, 16);
+            var ciphertext = encryptedBin.slice(16, encryptedBin.byteLength - 32);
+            var ivAndCiphertext = encryptedBin.slice(0, encryptedBin.byteLength - 32);
+            var mac = encryptedBin.slice(encryptedBin.byteLength - 32, encryptedBin.byteLength);
+
+            return verifyMAC(ivAndCiphertext, mac_key, mac).then(function() {
+                return window.axolotl.crypto.decrypt(aes_key, ciphertext, iv);
+            });
+        },
+
+        encryptAttachment: function(plaintext, keys, iv) {
+            var aes_key = keys.slice(0, 32);
+            var mac_key = keys.slice(32, 64);
+
+            return window.axolotl.crypto.encrypt(aes_key, plaintext, iv).then(function(ciphertext) {
+                var ivAndCiphertext = new Uint8Array(16 + ciphertext.byteLength);
+                ivAndCiphertext.set(new Uint8Array(iv));
+                ivAndCiphertext.set(new Uint8Array(ciphertext), 16);
+
+                return axolotl.crypto.sign(mac_key, ivAndCiphertext.buffer).then(function(mac) {
+                    var encryptedBin = new Uint8Array(16 + ciphertext.byteLength + 32);
+                    encryptedBin.set(ivAndCiphertext);
+                    encryptedBin.set(new Uint8Array(mac), 16 + ciphertext.byteLength);
+                    return encryptedBin.buffer;
+                });
+            });
+        }
+    };
+})();

libtextsecure/helpers.js

@@ -137,7 +137,7 @@ var handleAttachment = function(attachment) {
     }
 
     function decryptAttachment(encrypted) {
-        return textsecure.protocol.decryptAttachment(
+        return textsecure.crypto.decryptAttachment(
             encrypted,
             attachment.key.toArrayBuffer()
         );

libtextsecure/sendmessage.js

@@ -234,7 +234,7 @@ window.textsecure.messaging = function() {
         proto.key = axolotl.crypto.getRandomBytes(64);
 
         var iv = axolotl.crypto.getRandomBytes(16);
-        return textsecure.protocol.encryptAttachment(attachment.data, proto.key, iv).then(function(encryptedBin) {
+        return textsecure.crypto.encryptAttachment(attachment.data, proto.key, iv).then(function(encryptedBin) {
             return textsecure.api.putAttachment(encryptedBin).then(function(id) {
                 proto.id = id;
                 proto.contentType = attachment.contentType;