Thanks a lot for the tutorial, seems quite doable. Btw, is it possible/common to find several keys that give good sound, and would it be better to repeat the process with different tracks to get the "best" key?
As for the adxs, unfortunately I only have 9 and I think I uploaded the best two. Though I could upload the OSTs in mp3 (+-50 tracks)instead if you want.
I think it is possible to find several keys that give good sound, but I've never kept searching after I found a working one. A search for a "best" key is not practical. The scaletotal method for ranking keys is only able to work because the encryption makes the higher bits evenly distributed between zero and one, while higher bits should be more likely to be zero. Lower bits, however, should be more evenly distributed between zero and one anyway. So a key can be found to match the high flipped bits, but the low flipped bits are hidden under the "noise" of the music itself. So the differences in scaletotals for keys becomes meaningless at low values (being on the order of 100). As it takes a fair amount of searching the key space to find something that even sounds right, I don't think searching for other keys makes sense. If you can find some other artifact left by the incomplete decryption to use as a ranking method (maybe there's a high frequency component that'll show up in a spectrum analysis?) then maybe improvements would be possible.
Hmm, it would seem that I don't have the OST, looks like I missed out when #gamemp3s released it. I'll be able to pick it up anyway. Trying to get the game, too, I'll put up the ADXs if I find 'em.
I know ADX decryption isn't a big deal anymore, since it's pretty much "solved", but I was thinking about it again lately (we've been discussing cryptography at school). I came up with a new way to compute keys, faster than degod's brute forcing, requiring no user intervention, and precise. guessadx 0.1 The readme.txt has details. It answers the questions about multiple keys, some keys have close relatives, others are truly unique.