Thanks a lot. I tried to get key from address 0xFFFF1D0C (this is ROM offset, but file offset is 0x3F1D0C) and use IV from SX150IS got from address mentioned here in Powershot SX150 IS Porting Thread. Works great.
Great. Can you confirm whether you need to hold play while doing the firmware update on SX120? If so, it would be nice to fix for that cam, or at least correct the notes.
P.S. I wanted to use correct key/IV because I need no-bootable mode. And it didn't want to work without right key/IV pair. More precisely, CHDK was loading but with errors in .flt files.
FWIW, the module .flt files are not directly affected by the FI2 keys in any way. In autobuilds, the modules are only built once per CPU architecture. The keys are only used to encode the core CHDK binary into PS.FI2 format so it can be manually loaded with firm update.
However, the .flt files must be compatible with the core CHDK binary you use, as defined by various version numbers and exported symbols. If you build your own CHDK version without FI2 keys, you get the core in DISKBOOT.BIN (for autobooting) and the module .flt files but no PS.FI2. So if you copy that on to a card that had a different build installed, the PS.FI2 will be the core from the old build, which may not be compatible with your new modules.