Threema is pretty old, before the Signal Protocol was well known. There was a talk about the security at 33C3 here: https://media.ccc.de/v/33c3-8062-a_look_int

Threema is pretty old, before the Signal Protocol was well known. There was a talk about the security at 33C3 here: https://media.ccc.de/v/33c3-8062-a_look_into_the_mobile_messaging_black_box https://media.ccc.de/v/33c3-8062-a_look_into_the_mobile_mess...