Deriving keys for different purposes requires domain separation. HKDF provides a defined construction for key derivation.
Evaluation approach
Specify purpose and protocol context. Avoid accidental key sharing between encryption and authentication roles.
Application example
Separate derivation contexts can distinguish file-protection keys from transaction-related keys.
Limits and considerations
HKDF is not a password-hardening method that turns weak user passwords into strong input key material.
Why document labels?
Two teams reusing a label for different purposes can undermine separation. Version labels with the protocol and check identical client-server representation.
Checks and decisions
- Separate purposes
- Define context
- Verify test vectors
Sources
The primary references above provide the technical basis. Example workflows and evaluation suggestions are this publication’s explanations, not independent test results for a particular product.