Whatever. A theoretical one. You name it. From whatever a political angle you are watching, you can probably notice quite a number of them in the world. By definition a regime is considered a tyranny once it starts doing harder to keep the power at whatever the costs than to improve well-being of the people. In the past people could oppose peacefully or violently, today they can't. My hypothesis is that a society where anybody can easily communicate to anybody secretly at any time will become an effectively self-regulating organism making cancers of organized crime and tyranny nonviable. Special services like the NSA or Roskomnadzor say they need to be able to eavesdrop and/or block everything to fight the bad guys, I believe this probably is a mistake (or a lie - everybody just wants the One ring and fighting the darkness is just an excuse to keep it) so whatever an app they try and fail to have/block has my sympathies. Once an app or whatever emerges able to stand the ground long enough and easy enough for everybody to use we'll see.