diff options
Diffstat (limited to 'plugins/omemo/src/logic/decrypt.vala')
| -rw-r--r-- | plugins/omemo/src/logic/decrypt.vala | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/plugins/omemo/src/logic/decrypt.vala b/plugins/omemo/src/logic/decrypt.vala new file mode 100644 index 00000000..cfbb9c58 --- /dev/null +++ b/plugins/omemo/src/logic/decrypt.vala @@ -0,0 +1,211 @@ +using Dino.Entities; +using Qlite; +using Gee; +using Signal; +using Xmpp; + +namespace Dino.Plugins.Omemo { + + public class OmemoDecryptor : Xep.Omemo.OmemoDecryptor { + + private Account account; + private Store store; + private Database db; + private StreamInteractor stream_interactor; + private TrustManager trust_manager; + + public override uint32 own_device_id { get { return store.local_registration_id; }} + + public OmemoDecryptor(Account account, StreamInteractor stream_interactor, TrustManager trust_manager, Database db, Store store) { + this.account = account; + this.stream_interactor = stream_interactor; + this.trust_manager = trust_manager; + this.db = db; + this.store = store; + } + + public bool decrypt_message(Entities.Message message, Xmpp.MessageStanza stanza, Conversation conversation) { + StanzaNode? encrypted_node = stanza.stanza.get_subnode("encrypted", NS_URI); + if (encrypted_node == null || MessageFlag.get_flag(stanza) != null || stanza.from == null) return false; + + if (message.body == null && Xep.ExplicitEncryption.get_encryption_tag(stanza) == NS_URI) { + message.body = "[This message is OMEMO encrypted]"; // TODO temporary + } + if (!Plugin.ensure_context()) return false; + int identity_id = db.identity.get_id(conversation.account.id); + + MessageFlag flag = new MessageFlag(); + stanza.add_flag(flag); + + Xep.Omemo.ParsedData? data = parse_node(encrypted_node); + if (data == null || data.ciphertext == null) return false; + + + foreach (Bytes encr_key in data.our_potential_encrypted_keys.keys) { + data.is_prekey = data.our_potential_encrypted_keys[encr_key]; + data.encrypted_key = encr_key.get_data(); + Gee.List<Jid> possible_jids = get_potential_message_jids(message, data, identity_id); + if (possible_jids.size == 0) { + debug("Received message from unknown entity with device id %d", data.sid); + } + + foreach (Jid possible_jid in possible_jids) { + try { + uint8[] key = decrypt_key(data, possible_jid); + string cleartext = arr_to_str(aes_decrypt(Cipher.AES_GCM_NOPADDING, key, data.iv, data.ciphertext)); + + // If we figured out which real jid a message comes from due to decryption working, save it + if (conversation.type_ == Conversation.Type.GROUPCHAT && message.real_jid == null) { + message.real_jid = possible_jid; + } + + message.body = cleartext; + message.encryption = Encryption.OMEMO; + + trust_manager.message_device_id_map[message] = data.sid; + return true; + } catch (Error e) { + debug("Decrypting message from %s/%d failed: %s", possible_jid.to_string(), data.sid, e.message); + } + } + } + + if ( + encrypted_node.get_deep_string_content("payload") != null && // Ratchet forwarding doesn't contain payload and might not include us, which is ok + data.our_potential_encrypted_keys.size == 0 && // The message was not encrypted to us + stream_interactor.module_manager.get_module(message.account, StreamModule.IDENTITY).store.local_registration_id != data.sid // Message from this device. Never encrypted to itself. + ) { + db.identity_meta.update_last_message_undecryptable(identity_id, data.sid, message.time); + trust_manager.bad_message_state_updated(conversation.account, message.from, data.sid); + } + + debug("Received OMEMO encryped message that could not be decrypted."); + return false; + } + + public Gee.List<Jid> get_potential_message_jids(Entities.Message message, Xmpp.Xep.Omemo.ParsedData data, int identity_id) { + Gee.List<Jid> possible_jids = new ArrayList<Jid>(); + if (message.type_ == Message.Type.CHAT) { + possible_jids.add(message.from.bare_jid); + } else { + if (message.real_jid != null) { + possible_jids.add(message.real_jid.bare_jid); + } else if (data.is_prekey) { + // pre key messages do store the identity key, so we can use that to find the real jid + PreKeySignalMessage msg = Plugin.get_context().deserialize_pre_key_signal_message(data.encrypted_key); + string identity_key = Base64.encode(msg.identity_key.serialize()); + foreach (Row row in db.identity_meta.get_with_device_id(identity_id, data.sid).with(db.identity_meta.identity_key_public_base64, "=", identity_key)) { + try { + possible_jids.add(new Jid(row[db.identity_meta.address_name])); + } catch (InvalidJidError e) { + warning("Ignoring invalid jid from database: %s", e.message); + } + } + } else { + // If we don't know the device name (MUC history w/o MAM), test decryption with all keys with fitting device id + foreach (Row row in db.identity_meta.get_with_device_id(identity_id, data.sid)) { + try { + possible_jids.add(new Jid(row[db.identity_meta.address_name])); + } catch (InvalidJidError e) { + warning("Ignoring invalid jid from database: %s", e.message); + } + } + } + } + return possible_jids; + } + + public override uint8[] decrypt_key(Xmpp.Xep.Omemo.ParsedData data, Jid from_jid) throws GLib.Error { + int sid = data.sid; + uint8[] ciphertext = data.ciphertext; + uint8[] encrypted_key = data.encrypted_key; + + Address address = new Address(from_jid.to_string(), sid); + uint8[] key; + + if (data.is_prekey) { + int identity_id = db.identity.get_id(account.id); + PreKeySignalMessage msg = Plugin.get_context().deserialize_pre_key_signal_message(encrypted_key); + string identity_key = Base64.encode(msg.identity_key.serialize()); + + bool ok = update_db_for_prekey(identity_id, identity_key, from_jid, sid); + if (!ok) return null; + + debug("Starting new session for decryption with device from %s/%d", from_jid.to_string(), sid); + SessionCipher cipher = store.create_session_cipher(address); + key = cipher.decrypt_pre_key_signal_message(msg); + // TODO: Finish session + } else { + debug("Continuing session for decryption with device from %s/%d", from_jid.to_string(), sid); + SignalMessage msg = Plugin.get_context().deserialize_signal_message(encrypted_key); + SessionCipher cipher = store.create_session_cipher(address); + key = cipher.decrypt_signal_message(msg); + } + + if (key.length >= 32) { + int authtaglength = key.length - 16; + uint8[] new_ciphertext = new uint8[ciphertext.length + authtaglength]; + uint8[] new_key = new uint8[16]; + Memory.copy(new_ciphertext, ciphertext, ciphertext.length); + Memory.copy((uint8*)new_ciphertext + ciphertext.length, (uint8*)key + 16, authtaglength); + Memory.copy(new_key, key, 16); + data.ciphertext = new_ciphertext; + key = new_key; + } + + return key; + } + + public override string decrypt(uint8[] ciphertext, uint8[] key, uint8[] iv) throws GLib.Error { + return arr_to_str(aes_decrypt(Cipher.AES_GCM_NOPADDING, key, iv, ciphertext)); + } + + private bool update_db_for_prekey(int identity_id, string identity_key, Jid from_jid, int sid) { + Row? device = db.identity_meta.get_device(identity_id, from_jid.to_string(), sid); + if (device != null && device[db.identity_meta.identity_key_public_base64] != null) { + if (device[db.identity_meta.identity_key_public_base64] != identity_key) { + critical("Tried to use a different identity key for a known device id."); + return false; + } + } else { + debug("Learn new device from incoming message from %s/%d", from_jid.to_string(), sid); + bool blind_trust = db.trust.get_blind_trust(identity_id, from_jid.to_string(), true); + if (db.identity_meta.insert_device_session(identity_id, from_jid.to_string(), sid, identity_key, blind_trust ? TrustLevel.TRUSTED : TrustLevel.UNKNOWN) < 0) { + critical("Failed learning a device."); + return false; + } + + XmppStream? stream = stream_interactor.get_stream(account); + if (device == null && stream != null) { + stream.get_module(StreamModule.IDENTITY).request_user_devicelist.begin(stream, from_jid); + } + } + return true; + } + + private string arr_to_str(uint8[] arr) { + // null-terminate the array + uint8[] rarr = new uint8[arr.length+1]; + Memory.copy(rarr, arr, arr.length); + return (string)rarr; + } + } + + public class DecryptMessageListener : MessageListener { + public string[] after_actions_const = new string[]{ }; + public override string action_group { get { return "DECRYPT"; } } + public override string[] after_actions { get { return after_actions_const; } } + + private HashMap<Account, OmemoDecryptor> decryptors; + + public DecryptMessageListener(HashMap<Account, OmemoDecryptor> decryptors) { + this.decryptors = decryptors; + } + + public override async bool run(Entities.Message message, Xmpp.MessageStanza stanza, Conversation conversation) { + decryptors[message.account].decrypt_message(message, stanza, conversation); + return false; + } + } +} + |