CCS/BQ78350: 1

Vimmy Kumari

Prodigy 30 points

Part Number: BQ78350
Other Parts Discussed in Thread: , BQ40Z50, BQ26100,

Tool/software: Code Composer Studio

HI,

I am struggling with the SHA-1 authentication done by the bq78350.

I wanted to know how bq78350 is communicating with the device to authenticate the Key.

In datasheet it is given that it is generating HMAC-2 using SHA - 1 and writing 160 bit to manufacturing input.

so is this manufacturing input is of host or device?

over 4 years ago

0 Matt Sunna over 4 years ago

TI__Guru* 80633 points

Hi Vimmy,

ManufactuererInput is a command for the BQ78350-R1A (see command 0x2F in the TRM). (I notice you wrote BQ78350 in the post, but I recommend using the BQ78350-R1A which comes loaded with the latest device firmware).

Here are a couple of links that might help explain the SHA-1 authentication a little better. They are for similar devices:

Example logic analyzer capture on BQ40Z50: https://e2e.ti.com/support/power-management/f/196/t/794306?BQ40Z50-R1-SHA-1

BQ26100 SHA-1 app note: https://www.ti.com/lit/an/slua389a/slua389a.pdf

Best regards,

Matt

0 Vimmy Kumari over 4 years ago in reply to Matt Sunna

Prodigy 30 points

HI,

I have a controller connected with BQ78350 which needs to authenticate BQ78350.

So, I have doubt like whether we need to implement SHA-1 in our host controller or Host will just request for authentication and read from the bq78350?

Kindly resolve my query.

Thanks & Regards

Vimmy Kumari

0 Matt Sunna over 4 years ago in reply to Vimmy Kumari

TI__Guru* 80633 points

Hi Vimmy,

The authentication feature can be used by the host to check whether a battery is from a trusted source. For example, if someone tries to insert a non-approved battery in the system the host can detect this using the SHA-1 feature. This is not required. You can set a unique authentication key (command 0x0037) and use the command 0x2F to perform the authentication.

The other security feature is the SEAL command and you can modify the SEAL keys. This protects against someone without the password trying to modify the data flash of the device or using some commands.

Best regards,

Matt

0 Vimmy Kumari over 4 years ago in reply to Matt Sunna

Prodigy 30 points

HI,

so we need to call out the authenticate() to perform the Authentication. It will automatically authenticate.

No need to write Algorithm in our host card?

0 Matt Sunna over 4 years ago in reply to Vimmy Kumari

TI__Guru* 80633 points

Vimmy,

If you want to use the authentication feature, you first send the command (0x2F) and wait for the device to compute the SHA-1. You then read back the BQ78350-R1 response from 0x2F using a block read. The host will need to verify that the data it reads is correct. You can have the host compare the reading to the expected response.

See the example I sent before: https://e2e.ti.com/support/power-management/f/196/t/794306?BQ40Z50-R1-SHA-1

Best regards,

Matt

Power management

Power management forum

CCS/BQ78350: 1