SLUAAQ0 March   2025 BQ27Z558 , BQ27Z561 , BQ27Z561-R1 , BQ27Z561-R2 , BQ27Z746 , BQ27Z758 , BQ28Z610 , BQ28Z610-R1 , BQ34Z100-G1 , BQ34Z100-R2 , BQ4050 , BQ40Z50 , BQ40Z50-R1 , BQ40Z50-R2 , BQ40Z80 , BQ41Z50 , BQ41Z90

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Generating a Key File with BQKEYPACKAGER
    1. 1.1 SHA1 Process
      1. 1.1.1 How to Calculate SHA1 Key
    2. 1.2 SHA256 Process
    3. 1.3 ECC Process
  5. 2Programming a Key Into the Fuel Gauge With BQKEYPROGRAMMER
  6. 3Programming Keys in Production
  7. 4Summary
  8. 5References

1 Generating a Key File with BQKEYPACKAGER

BQKEYPACKAGER is intended only for an OEM to allow packaging of the authentication key. The authentication key is entered along with a password that is used in an algorithm to encrypt the file. After testing using BQKEYPROGRAMMER or BQSTUDIO, an OEM can then send the created file and password to a packmaker. Texas Instruments battery gauges have 3 methods of authentication, SHA1,SHA256, and ECC.

The output of the BQKEYPACKAGER tool is a .bqk file. This file is an encrypted output of the key generated using the tool. For the packaged .bqk file there are 2 options for output. A single file that encompasses the entire key or 2 separate files that each have one half of the key, these being part F and part C. When programming the key in production, the key can be programmed one half at a time or both halves at the same time. This allows for separate halves of the key to be programed at separate times and locations during production. For example, if you have a manufacturing flow with 2 manufacturers that the battery pack goes through. Each manufacturer can be given one half of the key to program into the gauge. This increases the security of the key as no single manufacturer has the entire key, only the OEM or designer has the key.

Note: Texas Instruments is not responsible for the security of any key packaged or programmed using BQKEYPACKAGER or BQKEYPROGRAMMER respectively. The user is responsible to make sure the key is kept secure and to limit the number of parties that have access to any part of the key.
Split Key Production ExampleFigure 1-1 Split Key Production Example