I don't have time to register in the other forum so i will quote something here
I believe the efs-system partition is the “OTP” area he is referring to, even though it is not OTP.
I have not found thekeyanywhere else, and I don’t even believe there is any one time programmable flash on the board. There are regions of the eeprom that are protected by the software, but those contain the fazit id and notkeys, additionally the entire NOR is writeable from within QNX. Given that, he might have a MIB2 from Delphi which is apparently designed much differently than the Harman Becker unit
For OTP and NOR flash - ignore the S29 model it's just from that flash type pdf
The S29GL-S flash devices have 1024 bytes of one time programmable (OTP) memory. This Secure SiliconRegion (SSR) is divided into two areas, the lower 512B region, SSR Region 0, is Factory modifiable and the upper512B region, SSR Region 1, is Customer modifiable. SSR0 can be ordered Factory pre-programmed. SSR0 isFactory locked and cannot be Customer modified
What Harman did is to put the pkey there, btw it's the same in old MMI. This have nothing to do with the EEPROM or the efs partition. Sad but true.
You can read that region when chip is off with special reader or with custom code running on the mib.
Having said this i dont say it's impossible to use own keys but here are some important points to consider:
1. Still need to patch MIBRoot to ignore OTP
2. Dont touch the data keys only fec and/or metainfo as data key is used to verify other things
That's why i said it's not worth the effort because you still need to patch something in the unit.
Regards.