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/* SPDX-License-Identifier: GPL-2.0 */
* Copyright (C) 2021, Stephan Mueller <>
#ifndef _CRYPTO_KDF108_H
#define _CRYPTO_KDF108_H
#include <crypto/hash.h>
#include <linux/uio.h>
* Counter KDF generate operation according to SP800-108 section 5.1
* as well as SP800-56A section 5.8.1 (Single-step KDF).
* @kmd Keyed message digest whose key was set with crypto_kdf108_setkey or
* unkeyed message digest
* @info optional context and application specific information - this may be
* @info_vec number of optional context/application specific information entries
* @dst destination buffer that the caller already allocated
* @dlen length of the destination buffer - the KDF derives that amount of
* bytes.
* To comply with SP800-108, the caller must provide Label || 0x00 || Context
* in the info parameter.
* @return 0 on success, < 0 on error
int crypto_kdf108_ctr_generate(struct crypto_shash *kmd,
const struct kvec *info, unsigned int info_nvec,
u8 *dst, unsigned int dlen);
* Counter KDF setkey operation
* @kmd Keyed message digest allocated by the caller. The key should not have
* been set.
* @key Seed key to be used to initialize the keyed message digest context.
* @keylen This length of the key buffer.
* @ikm The SP800-108 KDF does not support IKM - this parameter must be NULL
* @ikmlen This parameter must be 0.
* According to SP800-108 section 7.2, the seed key must be at least as large as
* the message digest size of the used keyed message digest. This limitation
* is enforced by the implementation.
* SP800-108 allows the use of either a HMAC or a hash primitive. When
* the caller intends to use a hash primitive, the call to
* crypto_kdf108_setkey is not required and the key derivation operation can
* immediately performed using crypto_kdf108_ctr_generate after allocating
* a handle.
* @return 0 on success, < 0 on error
int crypto_kdf108_setkey(struct crypto_shash *kmd,
const u8 *key, size_t keylen,
const u8 *ikm, size_t ikmlen);
#endif /* _CRYPTO_KDF108_H */