SLUAAW0 May   2025 BQ41Z50

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Authentication Scheme Comparison
  6. 3ECC Key Programming Within the Pack Manufacturing Flow
  7. 4Gauge Authentication Flow of the BQ41z50 Product Family
  8. 5Host Authentication Flow of the BQ41z50 Product Family
  9. 6Authentication Flow in BQSTUDIO
  10. 7Summary
  11. 8References

3 ECC Key Programming Within the Pack Manufacturing Flow

The BQ41z50 contains several sets of keys for differing purposes which are noted in the Table 3-1.

Table 3-1 List of Key Pairs and Secrets
Key Owner Use
Host command key (public only) Customer Used to authenticate host commands
Gauge Authentication Key (private, public) Customer

Host generated and programed to BQ41z50 devices.

Used for battery-host system authentication.

The Gauge and Host production key pairs must go through a specific procedure to be generated and uploaded to the BQ41z50.

Key generation: Random 233 bit value for private key as 'x', generate public key as (x^-1)G, alternatively, generate a standard ECDSA key, and then (ECKCDSA private key) = (ECDSA private key)^-1

Key programming (Full access only): Write private key (30 bytes, LSB first) || public key (30 bytes, LSB first, compressed) to MAC 0x0038