It is not impossible, just very improbable. That, or sony, or the hacker used a string compare instead of a regular compare. (Nintendo did that for their code, effectively shortening the key to 4 digits, making it brute forcable). A regular compare compares N digits of a string. A string compare compares either N digit or up to the first 0 (whichever comes first, because a 0 terminates a string, not a key).
He didn't say he brute forced the entire file, he said he compiled a list of null terminated possible 'key sets' and processed those.
From the blog:
I didn’t use brute from 0 to FF^20. From the dumps I had made full of 20 byte arrays terminated by 0×0 I generated little more than 8,100,000 byte arrays of 20 bytes. That LIST was then transcended via the loop and located the correct key. Forget trying to bruteforce 255^20.. I would die before a key was found.
I'm not saying he did or didn't find a key, just stating how he claims to have done it...
I'm seeing posts all over the place flaming this guy so bad, and it's a shame. I wish the scene would be a tad nicer to these guys. Same thing happened when someone in the 360 scene figured out how to play AC brotherhood and NFS HP using any drive firmware and doing a dash and game update in a certain order which bypasses the AP 2.5 checks, while installing the required Kinect dash.
The guy posted in the forums and and there was a hundred pages of flaming and calling the poor guy an idiot until someone actually tried it and it worked. I was able to do the same process to my 360 and was playing the new games before the new LT flashes were released... and I don't even need to reflash due that exploit which was awesome.
I don't think this guy would make such a ridiculous claim unless he has it, and it's perfectly plausible for him to not want to release it, being the way he is getting flamed, so be nice people. He'll dig his own grave if he is lying