# Why does running AES more than one time guard against cracking?

According to the documentation(http://keepass.info/help/base/security.html), keepass runs the AES key transformation round more than once to increase security.

If cracking consists of trying random strings of characters until we find the "right" one, wouldn't running the key transformation over again just result in another "right" one being found with the same probability?

For example, if I protected a file with the password "dog", but the encrypted file was run twice through AES, wouldn't there be another solution to the second round which could be cracked by finding that one? My goal is to find "a" solution, and not necessarily "the" solution. Why is it the case that if something is run through 1 million rounds, that I can't just crack the last one?

• Depending on what exactly you mean, I have the feeling that the answer will be "yes, but the effort required would be $>2^{128}$" – SEJPM Dec 20 '16 at 20:11
• How would you know you succeeded? The result of encryption is indistinguishable from random - when implemented properly anyway. Of course, running encryption multiple times makes no sense if the password is not strong. – Maarten Bodewes Dec 21 '16 at 2:20