English [HackIM 2016] [Crypto 500 – Crypto question 5] Write Up

Description

Crypto Question 5 500 pts

Now you are one step away from knowing who is that WARRIOR. The Fighter who will decide the fate of war between the 2 countries. The Pride of One and Envey of the Other… You have got the secrete file which has the crucial information to identify the fighter. But the file is encrypted with a RSA-Private key. Good news you have its corresponding public key in a file. Bad news there are 49 other keys. Whos is the Fighter.Now

Resolution

We have a zip file that contains the rsa ciphered text and another file which contains 50 public keys.

The text has been encrypted using private key, so we can recover the clear testing the 50 public keys.

One of them gives the result :
"\x01\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00This fighter is a designation for two separate, heavily upgraded derivatives of the Su-35 'Flanker' jet plane. They are single-seaters designed by Sukhoi(KnAAPO).\n"

This fighter is a designation for two separate, heavily upgraded derivatives of the Su-35 ‘Flanker’ jet plane. They are single-seaters designed by Sukhoi(KnAAPO).

Flag was “Sukhoi Su-35“.

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