# Where can I find official test vectors for NIST SP 800-56C r1 Single Step KDF

NIST 800-56Cr1 describes a single and two (extract-expand) step KDF designed for use in key agreement routines. NIST declares that HKDF (RFC5869) is a version of the two-step variation so test vectors can be found in the RFC. However I am not able to find test vectors for the former, one-step variation.

There are some for KBKDF (aka SP 800-108) in the Cryptographic Algorithm Validation Program, but not for 800-56C specifically. Can someone point me to the official or other test vectors?

• Apologies, I thought you were seeking the test vectors for the HKDF in a single step, while the document defines (for a lack of a better word) a general construction of a different single step KDF that performs extraction and expansion in one atomic operation. This explanation to avoid similar answers. Personally I would avoid the construction altogether by the way. – Maarten Bodewes Nov 19 '18 at 2:35
• No worries. Id like to implement it as because Im interested in KDFs and half as an (personal) academic exercise (I think you learn a lot implementing specs). Its just super strange that they declare a family of KDFs and dont seem to care about somebody to be able to test them. – Patrick Favre Nov 19 '18 at 13:20
• As I indicated, somewhat abusively, I don't think that the persons in charge of handling KDF's are necessarily the most competent persons at NIST. I've had some discussions per email with one of them, and the person seemed entirely unphased by the fact that HSM's seemed to FIPS-certify different mechanisms, making them incompatible. This document seems to standardize an unnamed, half-arsed scheme based on original research. That you cannot create test vectors for half-defined schemes is just the final straw. – Maarten Bodewes Nov 19 '18 at 13:57
• One of the issues at NIST is that it seems to be focused on security rather than standardization. That results in the weird situation that they do not seem to standardize on any KDF - rather they describe each and every KDF that is considered secure. Since it is relatively easy to create a secure KDF given a secure PRF, they end up with oodles of schemes. So implementations based on NIST "standards" will likely be incompatible with each other, even on an API level. I propose renaming NIST crypto to National Institute for Security and Technology, because standardize they don't. – Maarten Bodewes Nov 19 '18 at 14:01
• It is indeed strange. Thanks for the entertaining insight Maarten :) – Patrick Favre Nov 19 '18 at 14:42

Since as of now (2018) there seems to be no official test vectors, I generated some of may own. The whole list covering SHA1, SHA256, SHA512 and HMAC-SHA256/SHA512 can be found here: https://github.com/patrickfav/singlestep-kdf/wiki/NIST-SP-800-56C-Rev1:-Non-Official-Test-Vectors

Here is a snippet:

### SHA-256

(z: afc4e154498d4770aa8365f6903dc83b, L: 16, fixedInfo: 662af20379b29d5ef813e655) = f0b80d6ae4c1e19e2105a37024e35dc6
(z: a3ce8d61d699ad150e196a7ab6736a63, L: 16, fixedInfo: ce5cd95a44ee83a8fb83f34c) = 5db3455a22b65edfcfde3da3e8d724cd
(z: a9723e56045f0847fdd9c1c78781c8b7, L: 16, fixedInfo: e69b6005b78f7d42d0a8ed2a) = ac3878b8cf357976f7fd8266923e1882
(z: a07a5e8df7ee1b2ce2a3d1348edfa8ab, L: 16, fixedInfo: e22a8ee34296dd39b56b31fb) = 70927d218b6d119268381e9930a4f256

(z: 3f892bd8b84dae64a782a35f6eaa8f00, L: 02, fixedInfo: ec3f1cd873d28858a58cc39e) = a7c0
(z: 3f892bd8b84dae64a782a35f6eaa8f00, L: 36, fixedInfo: ec3f1cd873d28858a58cc39e) = a7c0665298252531e0db37737a374651b368275f2048284d16a166c6d8a90a91a491c16f
(z: 3f892bd8b84dae64a782a35f6eaa8f00, L: 68, fixedInfo: ec3f1cd873d28858a58cc39e) = a7c0665298252531e0db37737a374651b368275f2048284d16a166c6d8a90a91a491c16f49641b9f516a03d9d6d0f4fe7b81ffdf1c816f40ecd74aed8eda2b8a3c714fa0

(z: 9ce5457e4a0eecc1c8709f7ef37a32e9, L: 16, fixedInfo: ) = 7d81e7d61acc06b90984ec4145469608


### HMAC-SHA256

(z: 6ee6c00d70a6cd14bd5a4e8fcfec8386, L: 16, salt: 532f5131e0a2fecc722f87e5aa2062cb, fixedInfo: 861aa2886798231259bd0314) = 13479e9a91dd20fdd757d68ffe8869fb
(z: cb09b565de1ac27a50289b3704b93afd, L: 16, salt: d504c1c41a499481ce88695d18ae2e8f, fixedInfo: 5ed3768c2c7835943a789324) = f081c0255b0cae16edc6ce1d6c9d12bc
(z: 98f50345fd970639a1b7935f501e1d7c, L: 16, salt: 3691939461247e9f74382ae4ef629b17, fixedInfo: 6ddbdb1314663152c3ccc192) = 56f42183ed3e287298dbbecf143f51ac

(z: 02b40d33e3f685aeae677ac344eeaf77, L: 02, salt: 0ad52c9357c85e4781296a36ca72039c, fixedInfo: c67c389580128f18f6cf8592) = be32
(z: 02b40d33e3f685aeae677ac344eeaf77, L: 36, salt: 0ad52c9357c85e4781296a36ca72039c, fixedInfo: c67c389580128f18f6cf8592) = be32e7d306d891028be088f213f9f947c50420d9b5a12ca69818dd9995dedd8e6137c710
(z: 02b40d33e3f685aeae677ac344eeaf77, L: 68, salt: 0ad52c9357c85e4781296a36ca72039c, fixedInfo: c67c389580128f18f6cf8592) = be32e7d306d891028be088f213f9f947c50420d9b5a12ca69818dd9995dedd8e6137c7104d67f2ca90915dda0ab68af2f355b904f9eb0388b5b7fe193c9546d45849133d

(z: 2c2438b6321fed7a9eac200b91b3ac30, L: 56, salt: 6199187690823def2037e0632577c6b1, fixedInfo: ) = b402fda16e1c2719263be82158972c9080a7bafcbe0a3a6ede3504a3d5c8c0c0e00fe7e5f6bb3afdfa4d661b8fbe4bd7b950cfe0b2443bbd
(z: 0ffa4c40a822f6e3d86053aefe738eac, L: 64, salt: 6199187690823def2037e0632577c6b1, fixedInfo: ) = 0486d589aa71a603c09120fb76eeab3293eee2dc36a91b23eb954d6703ade8a7b660d920c5a6f7bf3898d0e81fbad3a680b74b33680e0cc6a16aa616d078b256
(z: a801d997ed539ae9aa05d17871eb7fab, L: 08, fixedInfo: 03697296e42a6fdbdb24b3ec) = 1a5efa3aca87c1f4
(z: e9624e112f9e90e7bf8a749cf37d920c, L: 16, fixedInfo: 03697296e42a6fdbdb24b3ec) = ee93ca3986cc43516ae4e29fd7a90ef1