1
$\begingroup$

I'm working on an old CTF challenge where AES-128 was used on a 16 byte block. I have the round 10 key and the ciphertext. What techniques exist for obtaining the plaintext?

$\endgroup$
  • 2
    $\begingroup$ hint: search for AES master key Round Keys $\endgroup$ – kelalaka Nov 10 '18 at 18:04
-1
$\begingroup$

Since this is CTF, I'll give you some detailed hints.

  • Normally by using only a ciphertext, you cannot determine the plaintext, since for every key the deciphered ciphertext is a valid plaintext and some of them are perfect in English or any other language. So, some other information must be given to you for verification.
  • 16-Byte just means one block for AES.
  • There is a difference in key schedules between AES-128 and AES-182,AES-256.
  • Your CTF is not possible with the key schedules of AES-192 and AES-256
  • You have given only, one round key. The different key schedule of AES -128 will enable this.
  • Search for AES master key Round Keys ( in this site)
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.