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Original question:

AM2434: Secure boot with OSPI boot and keywriter

AM2434: OTP Keywriter keyrevision 1 with Cust MPK Hash all zeroes

Mark Orkenyi
Prodigy 60 points
Part Number: AM2434
Other Parts Discussed in Thread: UNIFLASH

Hi,

I'm currently testing the OTP keywriter on an AM243x launchpad however I ran into a strange outcome.

As you can see on the attached image, the keywriting process resulted in a keyrevision of 1 - meaning it is now an HSSE device using the SMPK, however the SMPK hash is all zeroes.
We moved the keywriter into our own project/toolchain and I was able to write in MSV data. However I may have forgotten to set the smpk key in the generator script, but the keyrevision was incremented.
Right now I'm unable to flash anything on the board, as once the uart_uniflash completed flashing, the update is aborted.

Is it anyhow possible to flash an image now with the smpk hash being 0 or this board is now unusable?

Thanks, 

Mark

  • 0
    Prodigy 60 points

    Hi,

    Some additional info:
    I tried another board, generated the certificate with the following parameters: 

    Fullscreen
    1
    -t tifek/ti_fek_public.pem -a keys_devel/aeskey.key -s keys_devel/smpk.pem
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

    Compiled and ran the keywriter on the launchpad. Keywriter finished successfully according to the UART logs.

    Checked the socid, but the smpk hash is still the original: 

    However if I try to the keywriter again, it fails with Keywriter Debug Response:0x200000

    So something is written in probably, but I can't see the correct key in the socid.
    The verify_hash.csv contains a hash for the smpk, and I definitely built the image with the correct keycert.h

    Do you have any idea what's happening?

    Thanks,

    Mark

  • 0
    TI__Mastermind 26015 points

    Hi ,

    Unfortunately, you have bricked the device and the device is now unusable for the matter. Please be very careful when using the OTP Key Writer. The disclaimer is clearly mentioned in the device datasheet.

    https://www.ti.com/lit/ds/symlink/am2434.pdf

    Best Regards,
    Aakash Kedia

  • 0 in reply to Aakash Kedia
    Prodigy 60 points

    Thanks for the confirmation!
    However, could you look at my previous comment please? Even if I write in the SMPK key, it's not visible in the socid.

    I'm using SDK 9.0.

    Mark

  • +1 in reply to Mark Orkenyi
    TI__Mastermind 26015 points

    Hi ,

    I don't think HSM ROM updates the SoC ID parser output if the device is still HSFS.

    Best Regards,
    Aakash

  • 0
    Prodigy 60 points

    Thanks, SMPKH and keyrev now seems to be correct.

    However I have another question regarding the next steps.
    Am I assuming correctly I would need a sysfw, sysfw-inner-cert and boardcfg signed with the smpk? 
    Do I have to create a uart_uniflash tiimage signed with the smpk also if I want to use the uart_uniflash method for flashing?

    Is there any example scripts or guide on how to create these? I didn't find anything in restricted security content.

    Thanks, Mark