Hawkynt

SP800-108-Feedback

NIST SP 800-108 Key Derivation Function in Feedback Mode. Uses HMAC with feedback-based PRF expansion where each iteration feeds the previous output back as input, following the NIST standardized specification.

Properties

Property	Value
Category	Key Derivation Functions
Sub-category	NIST SP 800-108 Feedback Mode
Security status	🛡️ Secure
Complexity	Intermediate
Inventor	NIST
Year	2009
Origin	🇺🇸 United States
Source	algorithms/kdf/sp800-108-feedback.js

Parameters

Parameter	Supported values
Key derivation sizes	1 byte (8 bits) to 65535 bytes (524280 bits)

Capabilities

Flag	Value
SaltRequired	Yes
NeedsKey	Yes

Security

Status: 🛡️ Secure

No vulnerabilities are recorded for this implementation.

Documentation

• NIST SP 800-108 Revision 1 - Recommendation for Key Derivation Using Pseudorandom Functions
• RFC 6803 - KBKDF with HMAC
• OpenSSL EVP_KDF-KB Documentation

References

• Botan SP800_108_Feedback Implementation
• BouncyCastle KBKDF Feedback
• rust-kbkdf Implementation

Test vectors

6 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — SP 800-108 Feedback Mode - HMAC-SHA1 Test Vector 1 (2 bytes)

Field	Value
label	37935cbae5f5b003398f8e3f
context	0976fdec7817d94d60c4e0c9091d82e38bcfc58d7fff0829a13d1b4455b8
outputLength	2
counterBits	32
outputLengthBits	32
hashAlgorithm	SHA-1
input	e6ea4e4f7178a81230a01da05705b9c8b902121b
expected	1092

Vector 2 — SP 800-108 Feedback Mode - HMAC-SHA1 Test Vector 2 (2 bytes)

Field	Value
label	6ee961f615859ca0aae6ace0
context	614e4b95faa64cbe30ce47d9c426536a54f62e51d5909f8216204075516f
outputLength	2
counterBits	32
outputLengthBits	32
hashAlgorithm	SHA-1
input	5b5e2c32e98f06aa4868eec0ec18d53904dc0c05
expected	419a

Vector 3 — SP 800-108 Feedback Mode - HMAC-SHA1 Test Vector 3 (2 bytes)

Field	Value
label	c1e9241ee2203b12ce1147be
context	46402d8c205c356e9a09755adc2bf243b55b14424b64db419e0ceb22c211
outputLength	2
counterBits	32
outputLengthBits	32
hashAlgorithm	SHA-1
input	6611cf92c30689b302b190a7b720359a6f79af93
expected	5e6f

Vector 4 — SP 800-108 Feedback Mode - HMAC-SHA1, 20 bytes (exactly one PRF block)

Field	Value
label	fa9877411df9bba2b96706ea
context	314f85d1e8bfa91f2419b25cca0eaeb5 8a6e77244b20fedcf458b6656cd0e67d a2e417151dcfaad5946efc97924c89c9 be7fea6ac66e7af8d165df9c252bfa0f 0d00f8850ca49177a0ccbeac1f0818ed 8d1d7aea7455c608b22771a18f1a7a99 74fd4b1bcc7641c404ce650a737ddc75 9232b662e2af403a
outputLength	20
counterBits	32
outputLengthBits	32
hashAlgorithm	SHA-1
input	3b674a2db34ddffba29091a0ad3077c9dd4cc245
expected	4371d87e4a58f982afdfb70dc632ed620d76f14d

Vector 5 — SP 800-108 Feedback Mode - HMAC-SHA256, 36 bytes (one group past the first block)

Field	Value
label	07d8f46f432b585c9c35aad27d3b34bf
context	acdea99ad3d17295e1dc11935595aadb 2c95d06fcf9ea5cb89e9f5d42b1ee042 60a4b706555e5524a900f5162da44f51
outputLength	36
counterBits	32
outputLengthBits	32
hashAlgorithm	SHA-256
input	abbef1c4c15ba0660f118f4e3078193d104d286f7aab95b88d71cc00ccd4f38a
expected	773ad91cc0e639a067cb586f246157f9 992874cb933f62c8b7383a5aa7198dc1 e11c5ab7

Vector 6 — SP 800-108 Feedback Mode - HMAC-SHA256, 48 bytes (two PRF blocks)

Field	Value
label	6b5b22df64669ecd796545637ba48f55
context	61312d1cf43b42197348acb6fb89f720 70be9b7e633545eb5f563dea9a45405c 573229fcd8450a50f3671228e3e7ae39 213a7c8982643b6992661aa0e950fefe
outputLength	48
counterBits	32
outputLengthBits	32
hashAlgorithm	SHA-256
input	ba9a647c679326716cf4b98700199fc4f8592e9fc68f794d80da1e974c89d52d
expected	bf6ec210daddb2b977e22fa5e15497fa dcd692428ec54561ce502966a8e89a86 e812c8421b1ff843a06a46b7ab43d112

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