signal-service-java - provisioning version
A Java library for communicating via Signal.
Unofficial fork!
This library is an unofficial fork where we publish our changes to the official library (upstream). This fork allows using the Signal servers without GCM and provides provisioning, i.e. linking devices, and some bugfixes. Use it at your own risk. OpenWhisperSystems is not responsible for this fork.
The library is available on Maven Central.
Implementing the Signal Protocol interfaces
The Signal encryption protocol is a stateful protocol, so libsignal-service users
need to implement the storage interface SignalProtocolStore
, which handles load/store
of your key and session information to durable media.
Creating keys
IdentityKeyPair identityKey = KeyHelper.generateIdentityKeyPair();
List<PreKeyRecord> oneTimePreKeys = KeyHelper.generatePreKeys(0, 100);
PreKeyRecord lastResortKey = KeyHelper.generateLastResortPreKey();
SignedPreKeyRecord signedPreKeyRecord = KeyHelper.generateSignedPreKey(identityKey, signedPreKeyId);
The above are then stored locally so that they're available for load via the SignalProtocolStore
.
Registering
At install time, clients need to register with the Signal server.
private final String URL = "https://my.signal.server.com";
private final TrustStore TRUST_STORE = new MyTrustStoreImpl();
private final String USERNAME = "+14151231234";
private final String PASSWORD = generateRandomPassword();
private final String USER_AGENT = "[FILL_IN]";
SignalServiceAccountManager accountManager = new SignalServiceAccountManager(URL, TRUST_STORE,
USERNAME, PASSWORD, USER_AGENT);
accountManager.requestSmsVerificationCode();
accountManager.verifyAccountWithCode(receivedSmsVerificationCode, generateRandomSignalingKey(),
generateRandomInstallId(), false);
accountManager.setGcmId(Optional.of(GoogleCloudMessaging.getInstance(this).register(REGISTRATION_ID)));
accountManager.setPreKeys(identityKey.getPublicKey(), lastResortKey, signedPreKeyRecord, oneTimePreKeys);
Sending text messages
SignalServiceMessageSender messageSender = new SignalServiceMessageSender(URL, TRUST_STORE, USERNAME, PASSWORD,
new MySignalProtocolStore(),
USER_AGENT, Optional.absent());
messageSender.sendMessage(new SignalServiceAddress("+14159998888"),
SignalServiceDataMessage.newBuilder()
.withBody("Hello, world!")
.build());
Sending media messages
SignalServiceMessageSender messageSender = new SignalServiceMessageSender(URL, TRUST_STORE, USERNAME, PASSWORD,
new MySignalProtocolStore(),
USER_AGENT, Optional.absent());
File myAttachment = new File("/path/to/my.attachment");
FileInputStream attachmentStream = new FileInputStream(myAttachment);
SignalServiceAttachment attachment = SignalServiceAttachment.newStreamBuilder()
.withStream(attachmentStream)
.withContentType("image/png")
.withLength(myAttachment.length())
.build();
messageSender.sendMessage(new SignalServiceAddress("+14159998888"),
SignalServiceDataMessage.newBuilder()
.withBody("An attachment!")
.withAttachment(attachment)
.build());
Receiving messages
SignalServiceMessageReceiver messageReceiver = new SignalServiceMessageReceiver(URL, TRUST_STORE, USERNAME,
PASSWORD, mySignalingKey,
USER_AGENT);
SignalServiceMessagePipe messagePipe = null;
try {
messagePipe = messageReceiver.createMessagePipe();
while (listeningForMessages) {
SignalServiceEnvelope envelope = messagePipe.read(timeout, timeoutTimeUnit);
SignalServiceCipher cipher = new SignalServiceCipher(new SignalServiceAddress(USERNAME),
new MySignalProtocolStore());
SignalServiceContent message = cipher.decrypt(envelope);
System.out.println("Received message: " + message.getDataMessage().get().getBody().get());
}
} finally {
if (messagePipe != null)
messagePipe.shutdown();
}
Legal things
Cryptography Notice
This distribution includes cryptographic software. The country in which you currently reside may have restrictions on the import, possession, use, and/or re-export to another country, of encryption software. BEFORE using any encryption software, please check your country's laws, regulations and policies concerning the import, possession, or use, and re-export of encryption software, to see if this is permitted. See http://www.wassenaar.org/ for more information.
The U.S. Government Department of Commerce, Bureau of Industry and Security (BIS), has classified this software as Export Commodity Control Number (ECCN) 5D002.C.1, which includes information security software using or performing cryptographic functions with asymmetric algorithms. The form and manner of this distribution makes it eligible for export under the License Exception ENC Technology Software Unrestricted (TSU) exception (see the BIS Export Administration Regulations, Section 740.13) for both object code and source code.
License
Copyright 2013-2016 Open Whisper Systems
Licensed under the AGPLv3: https://www.gnu.org/licenses/agpl-3.0.html