BlockSignal is a secure instant messaging application based on Signal Android which is developed by Open Whisper Systems. Moreover, it uses a blockchain-based identity, authentication and storage platform, Blockstack, to verify the identities of users so as to prevent possible Man-in-the-Middle attacks. This feature provides an automatized authentication ceremony mechanism which is the users’ responsibility to perform in the original Signal. Therefore, in BlockSignal, being secure does not depend on user security awareness.

This work is in the scope of master thesis and the corresponding research paper of Enes Altuncu under supervision of Professor Kemal Bıçakcı from TOBB University of Economics and Technology.


As BlockSignal has been developed for the academic purposes, it is not a fully-tested software to be used as a commercial product. Therefore, it may (most probably, does) contain some bugs which are not in our responsibility meaning that we may not always have time to solve the issues reported. However, it is recommended to report the possible issues to inform other developers that might encounter the same issues later.


You can freely use this application in your studies, projects etc. by obeying the rules of GPLv3 licence. If you want to use this repository in an academical research, please cite our related paper as the following:

# 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 <> 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 2019 Enes Altuncu Copyright 2011 Whisper Systems Copyright 2013-2017 Open Whisper Systems Licensed under the GPLv3: Google Play and the Google Play logo are trademarks of Google Inc.