Is it possible to recover the key to a decrypted file if you have the initialization vector and it uses RijndaelManaged in CBC mode? 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?

  • 1
    $\begingroup$ No ${}{}{}{}{}$ $\endgroup$
    – kelalaka
    Commented Apr 21, 2019 at 21:04
  • $\begingroup$ are you sure?? xD @kelalaka $\endgroup$ Commented Apr 21, 2019 at 21:56
  • 1
    $\begingroup$ Depends on the encryption mode. If the mode has a relationship between the key and IV (i.e. it is a very bad mode you shouldn't use) then maybe. Question as stated does not have enough information, but if the encryption was done using sane parameters and modes then no. $\endgroup$ Commented Apr 21, 2019 at 23:01
  • $\begingroup$ More duplicates: crypto.stackexchange.com/q/1512, crypto.stackexchange.com/q/63883 $\endgroup$ Commented Apr 22, 2019 at 2:01
  • $\begingroup$ it uses CBC mode and padding value PKCS7 is that going to make a differents? :) @puzzlepalace $\endgroup$ Commented Apr 22, 2019 at 11:33