2017 Duramax

[2007 5.9]

The code is not encrypted so they aren't trying to hide anything, it's just digitally signed to stop people modifying it.

Ross,

Can you explain this digital signature for those who don't understand it vs encryption?

[GMPX]

Ross,

Can you explain this digital signature for those who don't understand it vs encryption?

I had a link a few pages back to a Wiki article that demonstrated the signature system GM used.
https://forum.efilive.com/showthread...l=1#post238349

But as simple as I can put it.
A digital signature is used to validate data.
Encryption scrambles the data so it is not 'readable' until Decrypted.

Unfortunately the digital signatures these days are so complex they cannot be tricked and can valid ones can only be generated by GM.

Cheers,
Ross

[sn00py]

The code is not encrypted so they aren't trying to hide anything, it's just digitally signed to stop people modifying it.

Yes, I was referring to Bosch's apparent future plans to encrypt/decrypt on the fly.

[GMPX]

Right ok, yeah that sounds bad. These are the CPU's they are going to be using. Goodnight to tuning for anything running that.

[Cougar281]

Dumb question...Dont the newer tunable cummins ecms have a similar signing and a way to patch it so it'll accept unsigned calibrations?

Sent from my 2PS64 using Tapatalk

[GMPX]

Yes but they have an exploit to turn it off. The signing is solid, they just left a gap in the door. At this stage it doesn't look like GM made the same mistake.

[modpcm]

There is no encryption as such but there is SHA-256 signatures on every calibration segment and the OS, no external reflash bootloader permitted so the signature validation cannot be bypassed and to top it off the JTAG/BDM is 128bit password protected.
Be prepared to accept that these may never be tunable, nobody but GM can generate the SHA-256 signatures and if someone does they will likely be sued by GM because SHA-256 is not crackable.

Hi, do someone know what tool was used to confirm the JTAG/BDM is 128bit password protected , any board pictures available
tks

[GMPX]

We use P&E Micro's equipment for BDM purposes......and the BDM password is different on every ECM.

[modpcm]

Hi, do you recall the ecu family , were you able to access the pad board by removing the thin cover or it required to completely dismantle the box, tks

[GMPX]

CPU is a MPC5676R.
There is no BDM pads in a row, the connection points are spread out all over the PCB... and no we aren't showing where they are, we had to destroy an ECM to trace them out .
Forget BDM, honestly you are wasting your time.