Is it possible to recover the key to a decrypted file if you have the initialization vector and it uses RijndaelManaged? If so how?

The file I want to recover the key from is a xml that looks like this without encryption. It has a xml element called Test.

<?xml version="1.0" encoding="utf-8"?>
<Test />

When it is encrypted with the key stackoverflow (73868cb1848a216984dca1b6b0ee37bc = md5 hash) and the initialization vector below, the file look like this ¥4!¬Hw[î!71ôtž|!¢¬TÞ;u?þª-†•ÈωeߎKtSsbZ®ÕµR©Ù«í‹:

File looks like this

Initialization vector:

byte[] iv = new byte[]
    55, 66, 77, 192, 57, 100, 11, 111,
    25, 86, 96, 66, 22, 122, 133, 43

Is it possible to reverse the key from that or are it bulletproof?

  • it uses CBC mode and padding value PKCS7 is that going to make a differents? :) Commented Apr 22, 2019 at 18:42
  • I'm voting to close this question as off-topic because it belongs in a cryptography Stack Exchange, not the Reverse Engineering one. Commented Apr 23, 2019 at 17:26

1 Answer 1


From my limited cryptographical knowledge and a quick Google search to confirm it, no.

This would be a known-plaintext attack and AES is engineered to be resistant to it.

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