BQ78350: SHA-1 how achieve authentication

Hey Sébastien,

This FAQ post should address your question, https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1178237/faq-what-is-the-procedure-to-program-the-sha-1-secure-key

Regards,

Nick Richards

Hi,

I have several questions related to your explanations.

1) I can't change the key on a bq78350

Why you don't use "0x0037 AuthenticationKey(): This Manufacturer Access command allows users to change the authentication key. Sending the new authentication key through ManufacturerBlockAccess() is supported." to modify the key ?

Can you only change the key once? Afterwards we will never be able to change it again?

What is the default key in BQ?

2) I can't understand how authentication works.

In your explanations I don't see :

Generate SHA-1 input block B1 of 512 bytes (total input = 128-bit authentication key KD + 160-bit message M + 1 + 159 0s + 100100000).

What is "0s" ?

Why you don't use : "+ 1 + 159 0s + 100100000"

Tanks.

I can't answer on the thread "[FAQ] What is the procedure to program the SHA-1 secure key?" because I can't fill in the box "Device or reference".

Hey Sébastien,

1.) I believe you are only able to change the key once. The default key should be 0x0123456789ABCDEFFEDCBA9876543210. 

2.) 159 0s = 0000000000.... (there is literally 159 zeros)

Regards,

Nick Richards