Pre-Draft Call for Comments: Key Derivation Using Pseudorandom Functions
November 04, 2026

NIST is planning to revise Special Publication (SP) 800-108r1 (Revision 1), Recommendation for Key Derivation Using Pseudorandom Functions, and is seeking public feedback on the proposed changes. Recent research has identified security concerns that affect certain key-derivation constructions, particularly regarding output indistinguishability and key-control security. These findings motivate a reassessment of some existing constructions and their security requirements.

The planned revision may clarify the expected security properties of key-derivation functions, update constructions affected by recent cryptanalytic results, reconsider guidelines for CMAC-based constructions, and evaluate the continued need for Double-Pipeline Iteration Mode. NIST invites feedback on these topics, including potential impacts on existing implementations, interoperability, and validation.

See the full announcement for additional details and specific questions for public comment. Comments are requested by December 18, 2026, and may be submitted to [email protected].