[Event] Implement file encryption

lib/src/client.dart

@@ -134,6 +134,9 @@ class Client {
   /// Whether this client supports end-to-end encryption using olm.
   bool get encryptionEnabled => _olmAccount != null;
 
+  /// Whether this client is able to encrypt and decrypt files.
+  bool get fileEncryptionEnabled => false;
+
   /// Warning! This endpoint is for testing only!
   set rooms(List<Room> newList) {
     print("Warning! This endpoint is for testing only!");

lib/src/event.dart

@@ -22,8 +22,11 @@
  */
 
 import 'dart:convert';
+import 'dart:typed_data';
 import 'package:famedlysdk/famedlysdk.dart';
 import 'package:famedlysdk/src/utils/receipt.dart';
+import 'package:http/http.dart' as http;
+import 'package:matrix_file_e2ee/matrix_file_e2ee.dart';
 import './room.dart';
 
 /// All data exchanged over Matrix is expressed as an "event". Typically each client action (e.g. sending a message) correlates with exactly one event.
@@ -427,6 +430,59 @@ class Event {
         toUsers: users);
     return;
   }
+
+  /// Downloads (and decryptes if necessary) the attachment of this
+  /// event and returns it as a [MatrixFile]. If this event doesn't
+  /// contain an attachment, this throws an error.
+  Future<MatrixFile> downloadAndDecryptAttachment() async {
+    if (![EventTypes.Message, EventTypes.Sticker].contains(this.type)) {
+      throw ("This event has the type '$typeKey' and so it can't contain an attachment.");
+    }
+    if (!content.containsKey("url") && !content.containsKey("file")) {
+      throw ("This event hasn't any attachment.");
+    }
+    final bool isEncrypted = !content.containsKey("url");
+
+    if (isEncrypted && !room.client.encryptionEnabled) {
+      throw ("Encryption is not enabled in your Client.");
+    }
+    MxContent mxContent =
+        MxContent(isEncrypted ? content["file"]["url"] : content["url"]);
+
+    Uint8List uint8list;
+
+    // Is this file storeable?
+    final bool storeable = room.client.storeAPI.extended &&
+        content["info"] is Map<String, dynamic> &&
+        content["info"]["size"] is int &&
+        content["info"]["size"] <= ExtendedStoreAPI.MAX_FILE_SIZE;
+
+    if (storeable) {
+      uint8list = await room.client.store.getFile(mxContent.mxc);
+    }
+
+    // Download the file
+    if (uint8list == null) {
+      uint8list =
+          (await http.get(mxContent.getDownloadLink(room.client))).bodyBytes;
+      await room.client.store.storeFile(uint8list, mxContent.mxc);
+    }
+
+    // Decrypt the file
+    if (isEncrypted) {
+      if (!content.containsKey("file") ||
+          !content["file"]["key"]["key_ops"].contains("decrypt")) {
+        throw ("Missing 'decrypt' in 'key_ops'.");
+      }
+      final EncryptedFile encryptedFile = EncryptedFile();
+      encryptedFile.data = uint8list;
+      encryptedFile.iv = content["file"]["iv"];
+      encryptedFile.k = content["file"]["key"]["k"];
+      encryptedFile.sha256 = content["file"]["hashes"]["sha256"];
+      uint8list = await decryptFile(encryptedFile);
+    }
+    return MatrixFile(bytes: uint8list, path: "/$body");
+  }
 }
 
 enum MessageTypes {

lib/src/room.dart

@@ -34,6 +34,7 @@ import 'package:famedlysdk/src/utils/matrix_exception.dart';
 import 'package:famedlysdk/src/utils/matrix_file.dart';
 import 'package:famedlysdk/src/utils/mx_content.dart';
 import 'package:famedlysdk/src/utils/session_key.dart';
+import 'package:matrix_file_e2ee/matrix_file_e2ee.dart';
 import 'package:mime_type/mime_type.dart';
 import 'package:olm/olm.dart' as olm;
 
@@ -453,20 +454,29 @@ class Room {
     return resp["event_id"];
   }
 
-  Future<String> sendTextEvent(String message,
+  Future<String> sendTextEvent(String message, {String txid, Event inReplyTo}) {
-          {String txid, Event inReplyTo}) =>
+    String type = "m.text";
-      sendEvent({"msgtype": "m.text", "body": message},
+    if (message.startsWith("/me ")) {
+      type = "m.emote";
+      message = message.substring(4);
+    }
+    return sendEvent({"msgtype": type, "body": message},
         txid: txid, inReplyTo: inReplyTo);
+  }
 
   /// Sends a [file] to this room after uploading it. The [msgType] is optional
   /// and will be detected by the mimetype of the file.
   Future<String> sendFileEvent(MatrixFile file,
-      {String msgType = "m.file", String txid, Event inReplyTo}) async {
+      {String msgType = "m.file",
-    if (msgType == "m.image") return sendImageEvent(file);
+      String txid,
-    if (msgType == "m.audio") return sendVideoEvent(file);
+      Event inReplyTo,
-    if (msgType == "m.video") return sendAudioEvent(file);
+      Map<String, dynamic> info}) async {
     String fileName = file.path.split("/").last;
-
+    final bool sendEncrypted = this.encrypted && client.fileEncryptionEnabled;
+    EncryptedFile encryptedFile;
+    if (sendEncrypted) {
+      encryptedFile = await file.encrypt();
+    }
     final String uploadResp = await client.upload(file);
 
     // Send event
@@ -474,8 +484,25 @@ class Room {
       "msgtype": msgType,
       "body": fileName,
       "filename": fileName,
+      if (!sendEncrypted) "url": uploadResp,
+      if (sendEncrypted)
+        "file": {
           "url": uploadResp,
-      "info": {
+          "mimetype": mime(file.path),
+          "v": "v2",
+          "key": {
+            "alg": "A256CTR",
+            "ext": true,
+            "k": encryptedFile.k,
+            "key_ops": ["encrypt", "decrypt"],
+            "kty": "oct"
+          },
+          "iv": encryptedFile.iv,
+          "hashes": {"sha256": encryptedFile.sha256}
+        },
+      "info": info != null
+          ? info
+          : {
               "mimetype": mime(file.path),
               "size": file.size,
             }
@@ -484,38 +511,23 @@ class Room {
   }
 
   Future<String> sendAudioEvent(MatrixFile file,
-      {String txid, int width, int height, Event inReplyTo}) async {
+      {String txid, Event inReplyTo}) async {
-    String fileName = file.path.split("/").last;
+    return await sendFileEvent(file,
-    final String uploadResp = await client.upload(file);
+        msgType: "m.audio", txid: txid, inReplyTo: inReplyTo);
-    Map<String, dynamic> content = {
-      "msgtype": "m.audio",
-      "body": fileName,
-      "filename": fileName,
-      "url": uploadResp,
-      "info": {
-        "mimetype": mime(fileName),
-        "size": file.size,
-      }
-    };
-    return await sendEvent(content, txid: txid, inReplyTo: inReplyTo);
   }
 
   Future<String> sendImageEvent(MatrixFile file,
       {String txid, int width, int height, Event inReplyTo}) async {
-    String fileName = file.path.split("/").last;
+    return await sendFileEvent(file,
-    final String uploadResp = await client.upload(file);
+        msgType: "m.image",
-    Map<String, dynamic> content = {
+        txid: txid,
-      "msgtype": "m.image",
+        inReplyTo: inReplyTo,
-      "body": fileName,
+        info: {
-      "url": uploadResp,
-      "info": {
           "size": file.size,
-        "mimetype": mime(fileName),
+          "mimetype": mime(file.path.split("/").last),
           "w": width,
           "h": height,
-      },
+        });
-    };
-    return await sendEvent(content, txid: txid, inReplyTo: inReplyTo);
   }
 
   Future<String> sendVideoEvent(MatrixFile file,
@@ -528,41 +540,37 @@ class Room {
       int thumbnailHeight,
       Event inReplyTo}) async {
     String fileName = file.path.split("/").last;
-    final String uploadResp = await client.upload(file);
+    Map<String, dynamic> info = {
-    Map<String, dynamic> content = {
-      "msgtype": "m.video",
-      "body": fileName,
-      "url": uploadResp,
-      "info": {
       "size": file.size,
       "mimetype": mime(fileName),
-      },
     };
     if (videoWidth != null) {
-      content["info"]["w"] = videoWidth;
+      info["w"] = videoWidth;
     }
     if (thumbnailHeight != null) {
-      content["info"]["h"] = thumbnailHeight;
+      info["h"] = thumbnailHeight;
     }
     if (duration != null) {
-      content["info"]["duration"] = duration;
+      info["duration"] = duration;
     }
-    if (thumbnail != null) {
+    if (thumbnail != null && !(this.encrypted && client.encryptionEnabled)) {
       String thumbnailName = file.path.split("/").last;
-      final String thumbnailUploadResp = await client.upload(file);
+      final String thumbnailUploadResp = await client.upload(thumbnail);
-      content["info"]["thumbnail_url"] = thumbnailUploadResp;
+      info["thumbnail_url"] = thumbnailUploadResp;
-      content["info"]["thumbnail_info"] = {
+      info["thumbnail_info"] = {
         "size": thumbnail.size,
         "mimetype": mime(thumbnailName),
       };
       if (thumbnailWidth != null) {
-        content["info"]["thumbnail_info"]["w"] = thumbnailWidth;
+        info["thumbnail_info"]["w"] = thumbnailWidth;
       }
       if (thumbnailHeight != null) {
-        content["info"]["thumbnail_info"]["h"] = thumbnailHeight;
+        info["thumbnail_info"]["h"] = thumbnailHeight;
       }
     }
-    return await sendEvent(content, txid: txid, inReplyTo: inReplyTo);
+
+    return await sendFileEvent(file,
+        msgType: "m.video", txid: txid, inReplyTo: inReplyTo, info: info);
   }
 
   Future<String> sendEvent(Map<String, dynamic> content,

lib/src/store_api.dart

@@ -23,6 +23,7 @@
 
 import 'dart:async';
 import 'dart:core';
+import 'dart:typed_data';
 import 'package:famedlysdk/src/account_data.dart';
 import 'package:famedlysdk/src/presence.dart';
 import 'package:famedlysdk/src/utils/device_keys_list.dart';
@@ -60,6 +61,9 @@ abstract class StoreAPI {
 /// Responsible to store all data persistent and to query objects from the
 /// database.
 abstract class ExtendedStoreAPI extends StoreAPI {
+  /// The maximum size of files which should be stored in bytes.
+  static const int MAX_FILE_SIZE = 10 * 1024 * 1024;
+
   /// Whether this is a simple store which only stores the client credentials and
   /// end to end encryption stuff or the whole sync payloads.
   final bool extended = true;
@@ -114,4 +118,11 @@ abstract class ExtendedStoreAPI extends StoreAPI {
 
   /// Removes this event from the store.
   Future removeEvent(String eventId);
+
+  /// Stores the bytes of this file indexed by the [mxcUri]. Throws an
+  /// exception if the bytes are more than [MAX_FILE_SIZE].
+  Future<void> storeFile(Uint8List bytes, String mxcUri);
+
+  /// Returns the file bytes indexed by [mxcUri]. Returns null if not found.
+  Future<Uint8List> getFile(String mxcUri);
 }

lib/src/utils/matrix_file.dart

@@ -2,10 +2,20 @@
 
 import 'dart:typed_data';
 
+import 'package:matrix_file_e2ee/matrix_file_e2ee.dart';
+
 class MatrixFile {
   Uint8List bytes;
   String path;
 
+  Future<EncryptedFile> encrypt() async {
+    print("[Matrix] Encrypt file with a size of ${bytes.length} bytes");
+    final EncryptedFile encryptedFile = await encryptFile(bytes);
+    print("[Matrix] File encryption successfull");
+    this.bytes = encryptedFile.data;
+    return encryptedFile;
+  }
+
   MatrixFile({this.bytes, String path}) : this.path = path.toLowerCase();
   int get size => bytes.length;
 }

pubspec.lock

@@ -15,6 +15,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.5.2"
+  asn1lib:
+    dependency: transitive
+    description:
+      name: asn1lib
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.5.15"
   async:
     dependency: transitive
     description:
@@ -99,6 +106,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.1.2"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.1"
   code_builder:
     dependency: transitive
     description:
@@ -148,6 +162,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.2.7"
+  encrypt:
+    dependency: transitive
+    description:
+      name: encrypt
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "4.0.0"
   ffi:
     dependency: transitive
     description:
@@ -253,6 +274,15 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.12.6"
+  matrix_file_e2ee:
+    dependency: "direct main"
+    description:
+      path: "."
+      ref: "1.x.y"
+      resolved-ref: "2ca458afed599e1421229460d7c9e9248bb86140"
+      url: "https://gitlab.com/famedly/libraries/matrix_file_e2ee.git"
+    source: git
+    version: "1.0.1"
   meta:
     dependency: transitive
     description:
@@ -292,11 +322,11 @@ packages:
     dependency: "direct main"
     description:
       path: "."
-      ref: bbc7ce10a52be5d5c10d2eb6c3591aade71356e2
+      ref: "1.x.y"
-      resolved-ref: bbc7ce10a52be5d5c10d2eb6c3591aade71356e2
+      resolved-ref: "79868b06b3ea156f90b73abafb3bbf3ac4114cc6"
       url: "https://gitlab.com/famedly/libraries/dart-olm.git"
     source: git
-    version: "0.0.0"
+    version: "1.0.0"
   package_config:
     dependency: transitive
     description:
@@ -325,6 +355,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.8.0+1"
+  pointycastle:
+    dependency: transitive
+    description:
+      name: pointycastle
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.2"
   pool:
     dependency: transitive
     description:

pubspec.yaml

@@ -15,7 +15,12 @@ dependencies:
   olm:
     git:
       url: https://gitlab.com/famedly/libraries/dart-olm.git
-      ref: bbc7ce10a52be5d5c10d2eb6c3591aade71356e2
+      ref: 1.x.y
+
+  matrix_file_e2ee:
+    git:
+      url: https://gitlab.com/famedly/libraries/matrix_file_e2ee.git
+      ref: 1.x.y
 
 dev_dependencies:
   test: ^1.0.0