Derive HKDF key

Category: KDF

Status: Registered and callable in the CyberChef 11.3.0 compatibility inventory.

Input / output: ArrayBuffer → string

Background: https://wikipedia.org/wiki/HKDF

What it does

A simple Hashed Message Authenticaton Code (HMAC)-based key derivation function (HKDF), defined in RFC5869.

Note

Status here means the operation name is implemented and callable. It does not by itself promise byte-for-byte parity for every upstream option. See Compatibility and current status for the verified scope and known boundaries.

Arguments and options

Arguments are positional. Keep their order when using bake() or Pipeline.then().

Index

Name

UI type

PyChef default

Accepted values / format

0

Salt

toggleString

{'string': '', 'option': 'Hex'}

''

1

Info

toggleString

{'string': '', 'option': 'Hex'}

''

2

Hashing function

option

'SHA256'

'MD2', 'MD4', 'MD5', 'SHA0', 'SHA1', 'SHA224', 'SHA256', 'SHA384', 'SHA512', 'SHA512/224', 'SHA512/256', 'RIPEMD128', 'RIPEMD160', 'RIPEMD256', 'RIPEMD320', 'HAS160', 'Whirlpool', 'Whirlpool-0', 'Whirlpool-T', 'Snefru'

3

Extract mode

argSelector

'with salt'

'with salt', 'no salt', 'skip'

4

L (number of output octets)

number

16

A Python integer or floating-point value

Recipe template

Important

This is a call template built from the documented defaults. Replace placeholder values such as empty keys, paths, patterns, or lookup data before running it.

from pychef import bake

input_value = b"example"
args = [{'string': '', 'option': 'Hex'}, {'string': '', 'option': 'Hex'}, 'SHA256', 'with salt', 16]
result = bake(input_value, [{"op": 'Derive HKDF key', "args": args}])
print(result)

Pipeline example

from pychef import Pipeline

args = [{'string': '', 'option': 'Hex'}, {'string': '', 'option': 'Hex'}, 'SHA256', 'with salt', 16]
transform = Pipeline().then('Derive HKDF key', *args)
result = transform(b"example")

Direct call

pychef.ops.run_operation runs any registered operation as a plain function, under the active ExecutionPolicy (safe defaults, no network):

from pychef.ops import run_operation

args = [{'string': '', 'option': 'Hex'}, {'string': '', 'option': 'Hex'}, 'SHA256', 'with salt', 16]
result = run_operation('Derive HKDF key', b"example", args=args)

Common operations also have typed helpers in Direct operations.

Low-level operation module

Warning

The module below is an internal implementation detail. It applies no execution policy, resource limits, or error sanitization; prefer bake(), Pipeline, or pychef.ops for application code.

The registered entry point lives in pychef.operations.by_operation.derive_hkdf_key. Direct calls receive the input value and a positional argument tuple:

from pychef.operations.by_operation.derive_hkdf_key import run

result = run(b"example", tuple([{'string': '', 'option': 'Hex'}, {'string': '', 'option': 'Hex'}, 'SHA256', 'with salt', 16]))
pychef.operations.by_operation.derive_hkdf_key.run(value, args)

Run this operation using its shared internal implementation.

Parameters:

  • value (str | bytes)

  • args (Sequence[Any])

Return type:

str | bytes