CrossCTF_2017: Paricle Collision Challenge
Category: Cryptography Points: 5 Description:
Our large hadron collider feeds off files that produces the same SHA1 hashsum value. Could you help us power up our collider? We will give you a flag in return! Our collider can be found at http://220.127.116.11:8081/
The collider feeds on distinct pairs of files that produces the same SHA1 hashsum value. However, the collider only accepts files it hasn't seen before!
This is a simple one, given that SHA1 is entirely broken and collisions are easily generated. For the purpose of this challenge, we will use a SHA1 collider, yielding two PDFs that result in the same hash.
Therefore, the flag is