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BQ40Z50 - SHA-1 Authentication

Prakash Balagangatharan
Expert 2440 points
Other Parts Discussed in Thread: BQ40Z50, BQ26100

Hi all, 

I am using BQ40Z50 fuel gauge battery. In this i am planning to implement the SHA1 authentication with MSP40F5335. I am studying the technical reference manual SLUUA43–December 2013 section 10 Device security. I have the few queries listed below as of now:

1. Is there any additional chip is required for this authentication or the MB85RC04V itself contains the authenticattion message?

2.Can we use the Battery management Battery Management Studio (V1.3.9) to check the SHA1 feature? If yes , what kind of procedure to be followed?

3. Is there any application note/sample codes provided by TI?

4. Is it possible to read the written authentication key using Battery management studio? Pls confirm.

If you guys help me regarding these queries, it will be more appreciated.

I have raised the same in to diffrent forum by mistakely, sorry for this.

Thanks in advance.

  • 0
    TI__Expert 3385 points

    Hi Prakash,

    Yes, you can use Battery Management Studio to check SHA-1 and to read the written authentication key.

    Please refer to this app note "How to Implement SHA-1/HMAC Authentication for bq26100"

    The device is different, but there is useful general information on SHA-1 implementation.

    Best,

    Justin

  • 0 in reply to Justin Erfan
    Expert 2440 points
    Hi,

    Already i went thriough the document. From that only i have the mentioned queries as below. can you please explain briefly
    1. Is there any additional chip is required for this authentication or the MB85RC04V itself contains the authenticattion message? Since the application note describe a separate chip is used for creating the authentication message.
    2.Can we use the Battery management Battery Management Studio (V1.3.9) to check the SHA1 feature? If yes , what kind of procedure to be followed? I am not sure the explanation given in section 10.4 of TRM, is there any sample procedure or application note available. I have used the code come along with the application note SLVA413–April 2010 in MSP430+bq26100. In this i can write the random message to 0x2F command but while reading not able get the written value since my authentication is always failure.

    Thanks in advance.
  • 0 in reply to Prakash Balagangatharan
    TI__Expert 3385 points
    Questions taken offline.
  • 0 in reply to Justin Erfan
    Expert 2440 points
    I have a doubt regarding authentication procedure explained in TRM chapter 10 section 10.4. Whatever the procedure explained in this section is differed from the procedure explained in the slva413 document and code. Also i have a one prototype code developed my seniores in this they are generating a random number using srand(xx), i am not sure how they are choosing this (xx)seed value. After generating the seed value they are writing the random number to (size+numbers+CRC) into the battery using command 0x2F. After that reading the value from the same command 0x2F. Then they have called the SHA-1 authentication library function by passing the read value as input parmeter. If i followed the same way writing is successfull, while reading i am geeting same value as 0xFD for all 20 bytes and final result is authentication failed. My assumption is during read also the same wriiten value to be get. Is it right? IS there any procedure to choose the seed value? Also "is that the above mentioned procedure is still applicable for bq40z50 also? or do i need to write a code as per the explanation given in data sheet section 10.4. Could you please guide me.