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AM623: Read public key hash from U-boot

Binson Binoy
Prodigy 130 points
Part Number: AM623
Other Parts Discussed in Thread: SHA-256

Tool/software:

Hi,

I’m working on a TI Sitara AM62x HS-SE device and need to read back the SHA-256 public key hash stored in the eFuse (written using the OTP key writer tool).

However, I’m running into the following issues in U-Boot:

  1. The fuse command is not available in my U-Boot (Unknown command 'fuse').

  2. The smccc and mrd commands are also not present.

  3. Attempting a memory read with md 0x430001F0 8 causes a Synchronous Abort, and the board resets. I assume this is due to secure memory protection.

I would like to know:

  • Can TI share any guidelines for safely accessing eFuse public key hash in U-Boot on HS-SE devices?

  • If this is only possible using the TI OTP key writer or a custom secure monitor interface, can you guide me on how to proceed?

Any help or documentation references would be greatly appreciated.
Thanks in advance!

Best regards,

Binson Binoy

  • +1
    TI__Guru 71451 points

    Hello,

    Binson Binoy said:
    Attempting a memory read with md 0x430001F0 8 causes a Synchronous Abort, and the board resets. I assume this is due to secure memory protection.

    Not sure how you got this address to read the active public key hash. Please refer to the section "10.2.3.5.29 tifs_secmgr Registers" of Security TRM to know about the correct address for reading active public key hash.

    Sample logs:

    => md.w 0x44234800 0x8
44234800: 601f b002 d97c b7b0 7dc4 a89c aad1 7be5  .`..|....}.....{
=> md.w 0x44234850 0x8
44234850: df60 f2d0 2b3e b10c c70e c7ed edc6 3dac  `...>+.........=

    Regards,

    Prashant