English [Sharif University CTF 2016] [Crypto 50 – Rail Fence Cipher] Write Up


Decrypt and find the flag.
Ciphertext is: AaY–rpyfneJBeaaX0n-,ZZcs-uXeeSVJ-sh2tioaZ}slrg,-ciE-anfGt.-eCIyss-TzprttFliora{GcouhQIadctm0ltt-FYluuezTyorZ-


Rail Fence Cipher is pretty straighforward, we use http://www.geocachingtoolbox.com/index.php?page=railFenceCipher and try every rails number till we get a plaintext since we know the flag format will be SharifCTF{flag_is_here}. The shift was 21 rails.
And the plaintext is:


Flag is : “QmFzZTY0IGlzIGEgZ2VuZXJpYyB0ZXJt“.

Leave a Reply

Your email address will not be published. Required fields are marked *