A cross-platform open source implementation and desktop client for the Threema Messenger App.

openMittsu is governed by the GNU GPL v2.0 license, but includes works from different people, licensed under different terms. See LICENSE for more information.

• CMake
• Qt 5
• LibSodium
• LibQrEncode or LibQrEncode-win32

Currently, the application has been built and tested on:

• Windows 7 using Visual Studio 2013
• Windows 7 using Visual Studio 2015
• Windows 10 using Visual Studio 2015
• Debian 8 using GCC 4.8 (AMD64)
• Debian 8 using GCC 4.9 (PPC)

Other platforms should work with no or minimal changes.

1. Clone this repository or extract the sources from the archive. If you clone the repository, do not forget to intialize the submodules (i.e. external git repositories):

git submodule init
git submodule sync
git submodule update --init --recursive

2. Install or build both LibSodium and LibQrEncode
3. Run CMake on the main directory. Point CMake to the installation locations of libSodium and LibQrEncode, if required. Use LIBSODIUM_INCLUDE_DIRS, LIBSODIUM_LIBRARIES, LIBQRENCODE_INCLUDE_DIR and LIBQRENCODE_LIBRARY, respectively.
4. Once Makefiles or a solution has been successfully generated, start the build process. On Windows, choosing a DEBUG configuration causes the application to show an additional terminal window containinig run-time debug information and logs.

Prerequisites on Debian/Ubuntu:

apt-get install libqt5core5a libqt5gui5 libqt5multimedia5 libqt5multimedia5-plugins libqt5sql5 libqt5sql5-sqlite libqt5widgets5 qt5-qmake qtbase5-dev qtbase5-dev-tools qtmultimedia5-dev libsodium-dev libqrencode-dev git

The application requires three input files.

• The contact database. This is a simple text file of the format:

# This is a comment line.
# Format of this file: 
# IDENTITY : PUBKEY : Nickname
# where 
# - IDENTITY is an eight character ID of the form [A-Z0-9]{8} and stands for a users public id,
# - PUBKEY is an 64 character key of the form [a-fA-F0-9]{64} and stands for a users 32-Byte long-term public key,
# - Nickname is an optional screen-name for the given identity.
# GROUPID : GROUPOWNER_IDENTITY : IDENTITY, IDENTITY, IDENTITY : Group Name
# where 
# - IDENTITY is an eight character ID of the form [A-Z0-9]{8} and stands for a users public id,
# - GROUPID is an 16 character key of the form [a-fA-F0-9]{16} and stands for a groups unique identifier,
# - GROUPOWNER_IDENTITY is an eight character ID of the form [A-Z0-9]{8} and stands for the group owners public id,
# - Group Name is the displayed title of the group.
ABCD1234 : aabbccddeeff00112233445566778899aabbccddeeff00112233445566778899 : Mr. Smith

• The client configuration, containing the ID and private key used by this client. It can easily be generated using the application.
  1. Export the identity from the Threema App. In the main menu, click on the uppermost entry containing your ID. Select "Save ID" and enter a password.
  2. In openMittsu, click on Identity, Load Backup.
  3. Enter the exported backup and the password.
  4. Choose a suitable location and let the application save the generated client configuration there.

openMittsu is a cross-platform open source implementation and desktop client for the Threema Messenger App. It has been created by reverse engineering the Threema mobile App and studying the publication from Jan Ahrens as well as the Threema Gateway.

The protocol Threema uses doesn't provide multi-device functionality (yet) which means you can't be connected with more than one device using the same ID simultaneously. However, if you disconnect your phone before connecting with openMittsu, you can use the same Threema ID for your phone and openMittsu. Please beware that you will only receive messages on one device. Alternatively, consult the Threema FAQ-answer on this topic: Can I install Threema on multiple devices?

No, please use the Threema app you purchased for generating an ID. You can use Threema on a second user on your phone or in an emulator if you need to as long as you have a legally purchased Threema app.

Yes, Threema tolerates the openMittsu project. However, if openMittsu will get abused, Threema may change their decision. Don't worry, your ID won't get banned just for using openMittsu (if you are using openMittsu just for instant messaging like you do with the Threema app).

No. The Threema GmbH is currently not interested in working on openMittsu.

No, if you want to send or receive Threema messages automatically, please use the official Threema Gateway API.

No. While a web client will connect to Threema through your phone, openMittsu is a standalone client which does not rely on your phone for connecting to the Threema servers. If you are interested in how a Threema web client could work, read lgrahl's thesis about SaltyRTC.

Without the initial research and publication by Jan Ahrens this project would have been so much more difficult, if not impossible.