On: A Crypto Challenge For The Telegram Developers

[javajosh]

Funny. But actually, the simplest contest that accurately describes Telegram's insanity is simply this:

::Given an unknown function f and a single output y, compute the input x that maps to y.::

Ready? Here's the output: ROSEBUD. Now I'll give $100k to anyone who can tell me x. Good luck!

[mintplant → javajosh]

The function is known--they publish how their algorithm works. The problem is that their contest doesn't account for the main problem with their system: its vulnerability to MITM attacks.

[javajosh → mintplant]

Okay, then let f XOR the input with a randomly generated integer. There is no loss of generality here.