0
$\begingroup$

I am looking for an application (Windows) or code example that might help me find patterns in an encrypted file. I have a ciphertext for which I want to see when a key is repeated. I am not trying to break the encryption - just test for when a pattern repeats if it does so.

I've searched, but haven't found anything yet.

Thanks.!

$\endgroup$
  • 1
    $\begingroup$ If you find a pattern that is considered breaking the cipher (or just a broken cipher), by many definitions. $\endgroup$ – Thomas M. DuBuisson May 21 '15 at 15:06
  • $\begingroup$ If the encryption uses proper IVs, key re-use won't harm (the defender). You probably won't even notice IV reuse as it's unlikely that in your file the plaintexts repeat.. $\endgroup$ – SEJPM May 21 '15 at 15:32
  • $\begingroup$ Let's restate the problem for two parties. Consider a prover that knows both pattern and the text, and a verifier only having commitments (that hide plaintext just like encryption). Such a prover can efficiently convince a verifier there is a repeated pattern in the text. IACR preprint 2008/357. $\endgroup$ – Vadym Fedyukovych May 21 '15 at 15:43
  • $\begingroup$ I understand that while that IS technically considered breaking the cipher, until the attacker can actually read/use the plaintext - they haven't really accomplished anything. Anyway, that said, I am testing different IVs, key lengths and patterns and trying to test for repeating keys. Surely someone has already created something that can take a file and search for repeating patterns. Why reinvent :) Thanks everyone. $\endgroup$ – Andy M May 24 '15 at 11:05

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.