signal cli

signal-cli provides an unofficial commandline, JSON-RPC and dbus interface for the Signal messenger.

AsamK
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Java

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 JSON-RPC interface (man page)
and D-BUS interface (man page) .
For the JSON-RPC interface there’s also a simple example client, written in Rust.

signal-cli needs to be kept up-to-date to keep up with Signal-Server changes.
The official Signal clients expire after three months and then the Signal-Server can make incompatible changes.
So signal-cli releases older than three months may not work correctly.

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) 21

  • 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}".tar.gz
sudo tar xf signal-cli-"${VERSION}".tar.gz -C /opt
sudo ln -sf /opt/signal-cli-"${VERSION}"/bin/signal-cli /usr/local/bin/

You can find further instructions on the Wiki:

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 need to follow the procedure below:

    • Attempt a SMS verification process first (signal-cli -a ACCOUNT register)

      • You will get an error 400 (InvalidTransportModeException), this is normal

    • Wait 60 seconds

    • Attempt a voice call verification by adding the --voice switch and wait for the call:

      signal-cli -a ACCOUNT register --voice

    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 environment

  2. 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