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 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 get_potential_message_jids(Entities.Message message, Xmpp.Xep.Omemo.ParsedData data, int identity_id) { Gee.List possible_jids = new ArrayList(); 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 decryptors; public DecryptMessageListener(HashMap 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; } } }