Olympiad-2017-bar

Here’s a nice crypto challenge I found in a paper about the Fourth International Students’ Olympiad in Cryptography. Can you solve it?

Playfair-bar

The Playfair cipher is an encryption method from the 19th century. Some say that a Playfair-encrypted message of 50 or less letters is still secure today, if the method is used properly. Let’s put this claim to the test.

Advent-2-bar

Crypto puzzle games in the advent time have a long tradition. Here are two nice ones of this year’s season.