NIST SP800-108 Key Derivation

PRF

Key

Label

Context

Output Length

Advanced Fixed Input Builder

Default layout matches NIST SP 800-108 counter mode: Counter | Label | 0x00 | Context | [L].

NIST default

Layout Preset

Counter Bits

Counter Encoding

Separator

The default NIST separator is a single 0x00 byte between Label and Context.

Output Length Segment

[L] is the requested output length encoded in bits. Keep it enabled for the standard construction.

[L] Bits

[L] Encoding

Segment Order

Pick the position for each active segment.

Counter

Label

Separator

Context

[L]

Current Sequence

Counter (32-bit Big-endian) -> Label -> Separator (0x00) -> Context -> [L] (32-bit Big-endian)

Derived Key

00148d26a5c85e0d8b993b3d814ed03f

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