[What does it technically do?]
6.20-6.35: It uses the utility/power exploit to gain kernel access and reboots into the updater with a special PRX running. This PRX uses the pspdecrypt functionality to decrypt the updater PRX when needed. This allows the updater to boot in the newer firmwares.
6.38/6.39: It uses my http_storage exploit to gain kernel access. Basically, http_storage has a vulnerability in it, where I can write -1 to anywhere in memory. (I'll make a post to explain it more in-depth soon)
[I'm a dev, sup?]
The source is included in the download package.
[Credits]
Davee - legend. Originally made 6.35/6.31 downgrader
bbtgp - legend. Continued updates to psardumper (pspdecrypt) and the signing application "prxEncrypter".
coyotebean - legend. Coninuted updates to psardumper (pspdecrypt) and large influence and research regarding cryptographics.
kgsws - legend. First application signed and method released.
Silverspring - legend. Lots and lots of info on KIRK where we'd still be in the dark without.
Bubbletune - BTCNF injection code and bits and bobs here ;D
[READ]
You run the application at your OWN risk. I am not help accountable if you PSP fucks up.