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_EFrie
Senior
January 16, 2026
Solved

STM32H563 DA obk password calculation

  • January 16, 2026
  • 2 replies
  • 176 views

I'm trying to understand how the HDPL1 is calculated based on an OBK file.

I have dumped the contents of HDPL1 / 0x0BDF0100 and can see that for a 16 length password, I have 96 bytes written, as follows

0x0BFD0100 to 0x0BFD0120, unknown calc, how is this calculated?

0x0BFD0120 to 0x0BFD0140 SHA-256 of password

0x0BFD0140 to 0x0BFD0160 zeros

Best answer by Jocelyn RICARD

Hello @_EFrie ,

The first 32 bytes contain the SHA-256 of the payload

Payload is the SHA-256 of password + remaining bytes

You can find this information in the RM0481 rev 4 Table 715 Definition of data to provision

Best regards

Jocelyn

2 replies

Jocelyn RICARD
Jocelyn RICARDBest answer
ST Employee
January 26, 2026

Hello @_EFrie ,

The first 32 bytes contain the SHA-256 of the payload

Payload is the SHA-256 of password + remaining bytes

You can find this information in the RM0481 rev 4 Table 715 Definition of data to provision

Best regards

Jocelyn

_EFrie
_EFrieAuthor
Senior
January 26, 2026

Thank you.