signal-cli

signal-cli is a commandline interface for the Signal messenger. It supports registering, verifying, sending and receiving messages. signal-cli uses a patched libsignal-service-java, extracted from the Signal-Android source code. For registering you need a phone number where you can receive SMS or incoming calls.

signal-cli is primarily intended to be used on servers to notify admins of important events. For this use-case, it has a daemon mode with D-BUS interface (man page) and JSON-RPC interface (documentation). For the JSON-RPC interface there's also a simple example client, written in Rust.

Installation

You can build signal-cli yourself or use the provided binary files, which should work on Linux, macOS and Windows. There's also a docker image and some Linux packages provided by the community.

System requirements:

• at least Java Runtime Environment (JRE) 17

• native library: libsignal-client

  The native libs are bundled for x86_64 Linux (with recent enough glibc), Windows and MacOS. For other systems/architectures see: Provide native lib for libsignal

Install system-wide on Linux

See latest version.

export VERSION=<latest version, format "x.y.z">
wget https://github.com/AsamK/signal-cli/releases/download/v"${VERSION}"/signal-cli-"${VERSION}"-Linux.tar.gz
sudo tar xf signal-cli-"${VERSION}"-Linux.tar.gz -C /opt
sudo ln -sf /opt/signal-cli-"${VERSION}"/bin/signal-cli /usr/local/bin/

You can find further instructions on the Wiki:

• Quickstart
• DBus Service

Usage

For a complete usage overview please read the man page and the wiki.

Important: The ACCOUNT is your phone number in international format and must include the country calling code. Hence it should start with a "+" sign. (See Wikipedia for a list of all country codes.)

• Register a number (with SMS verification)

  signal-cli -a ACCOUNT register
  

  You can register Signal using a landline number. In this case you can skip SMS verification process and jump directly to the voice call verification by adding the --voice switch at the end of above register command.

  Registering may require solving a CAPTCHA challenge: Registration with captcha

• Verify the number using the code received via SMS or voice, optionally add --pin PIN_CODE if you've added a pin code to your account

  signal-cli -a ACCOUNT verify CODE
  

• Send a message

  signal-cli -a ACCOUNT send -m "This is a message" RECIPIENT

• Pipe the message content from another process.

  uname -a | signal-cli -a ACCOUNT send --message-from-stdin RECIPIENT
  

• Receive messages

  signal-cli -a ACCOUNT receive
  

Hint: The Signal protocol expects that incoming messages are regularly received (using daemon or receive command). This is required for the encryption to work efficiently and for getting updates to groups, expiration timer and other features.

Storage

The password and cryptographic keys are created when registering and stored in the current users home directory:

$XDG_DATA_HOME/signal-cli/data/
$HOME/.local/share/signal-cli/data/

Building

This project uses Gradle for building and maintaining dependencies. If you have a recent gradle version installed, you can replace ./gradlew with gradle in the following steps.

1. Checkout the source somewhere on your filesystem with

   git clone https://github.com/AsamK/signal-cli.git
   

2. Execute Gradle:

   ./gradlew build
   

   2a. Create shell wrapper in build/install/signal-cli/bin:

   ./gradlew installDist
   

   2b. Create tar file in build/distributions:

   ./gradlew distTar
   

   2c. Create a fat tar file in build/libs/signal-cli-fat:

   ./gradlew fatJar
   

   2d. Compile and run signal-cli:

   ./gradlew run --args="--help"

Building a native binary with GraalVM (EXPERIMENTAL)

It is possible to build a native binary with GraalVM. This is still experimental and will not work in all situations.

1. Install GraalVM and setup the enviroment

2. Install prerequisites

3. Execute Gradle:

   ./gradlew nativeCompile
   

   The binary is available at build/native/nativeCompile/signal-cli

FAQ and Troubleshooting

For frequently asked questions and issues have a look at the wiki.

License

This project uses libsignal-service-java from Open Whisper Systems:

https://github.com/WhisperSystems/libsignal-service-java

Licensed under the GPLv3: http://www.gnu.org/licenses/gpl-3.0.html