Fix encryption bug, which made media unencryptable in Riot

lib/crypto/utils.cpp

@@ -203,9 +203,9 @@ encrypt_file(const std::string &plaintext)
 {
         mtx::crypto::EncryptedFile encryption_info;
 
-        // not sure if 16 bytes would be enough, 32 seems to be safe though
+        // iv has to be 16 bytes, key 32!
         BinaryBuf key = create_buffer(32);
-        BinaryBuf iv  = create_buffer(32);
+        BinaryBuf iv  = create_buffer(16);
 
         BinaryBuf cyphertext = AES_CTR_256_Encrypt(plaintext, key, iv);
 

tests/e2ee.cpp

@@ -1139,6 +1139,10 @@ TEST(Encryption, EncryptedFile)
         ASSERT_EQ(plaintext,
                   mtx::crypto::to_string(mtx::crypto::decrypt_file(
                     mtx::crypto::to_string(encryption_data.first), encryption_data.second)));
+	// IV needs to be 16 bytes/128 bits
+        ASSERT_EQ(16, encryption_data.second.iv.size());
+	// key needs to be 32 bytes/256 bits
+        ASSERT_EQ(32, encryption_data.second.key.k.size());
 
         json j                                            = R"({
   "type": "m.room.message",

tests/events.cpp

@@ -347,7 +347,7 @@ TEST(StateEvents, JoinRules)
           "type": "m.room.join_rules"
         })"_json;
 
-	EXPECT_EQ(data, json(ns::StateEvent<ns::state::JoinRules>(data)));
+        EXPECT_EQ(data, json(ns::StateEvent<ns::state::JoinRules>(data)));
 
         data = R"({
           "origin_server_ts": 1506761924018,
@@ -363,7 +363,7 @@ TEST(StateEvents, JoinRules)
           "type": "m.room.join_rules"
         })"_json;
 
-	EXPECT_EQ(data, json(ns::StateEvent<ns::state::JoinRules>(data)));
+        EXPECT_EQ(data, json(ns::StateEvent<ns::state::JoinRules>(data)));
 
         data = R"({
           "origin_server_ts": 1506761924018,
@@ -379,7 +379,7 @@ TEST(StateEvents, JoinRules)
           "type": "m.room.join_rules"
         })"_json;
 
-	EXPECT_EQ(data, json(ns::StateEvent<ns::state::JoinRules>(data)));
+        EXPECT_EQ(data, json(ns::StateEvent<ns::state::JoinRules>(data)));
 }
 
 TEST(StateEvents, Member)