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BQ27Z561-R2: 关于SHA-1 更新到SHA-256的兼容性问题

YongLiang Kong
Prodigy 80 points

Part Number: BQ27Z561-R2
Other Parts Discussed in Thread: SHA-256

Hi TI teams,

Project Background

Our old design uses TI BQ27541 fuel gauge with SHA-1-based pack authentication and pre-programmed SHA-1 keys. As BQ27541 is end-of-life, we plan to switch to BQ27Z561R2, which exclusively supports SHA-256 authentication with longer key requirements.

Queries

  1. For key reuse: Can we reuse the original SHA-1 key by adding leading zeros to match the SHA-256 key length required by BQ27Z561R2?
  2. For host compatibility: The customer’s main device only implements SHA-1 verification. After the battery pack switches to SHA-256 authentication:
    1. Will the original host still pass battery authentication normally?
    2. Do we have to update the host firmware to SHA-256 to maintain valid authentication communication?

    Best regards 

    Hogan

  • 0
    TI__Guru 52460 points

    Thank you for your attention to TI products. We are verifying your issue, please wait for our reply.

  • 0 回复 Vivian Gao
    TI__Guru 52460 points

    Plan for host firmware update — This is unavoidable for proper security
    Do NOT attempt key padding — It will not work and wastes development time
    Generate new SHA-256 keys — Use proper SHA-256 key generation, not converted SHA-1 keys
    Test authentication thoroughly — Verify the full challenge-response flow with new algorithm
    Consider transition strategy — If you have fielded products, plan for how to handle mixed battery populations