there are decypters for everything..
they're called fail0verflow tools in general, you can rip open anything encrypted with sony's kirk key.
this involves all executables and files inside firmware files, along with the firmware file itself. (if you're gonna do this, the split .tar for dev_flash inside the firmware .pup is an donkey to extract due to the nature of the tools)

decrypting the firmware is relatively pointless though, as the same files can be FTP'd out of flash0 with dev_blind

what comes to that recovery, while it does work it's originally designed to be used for downgrades and it messes with the system very badly. incase it goes wrong it has a chance to bring your ps3 to the state it doesn't power on anymore. use only as a very last resort.