026a733e66
SP800-108 defines three KDFs - this patch provides the counter KDF implementation. The KDF is implemented as a service function where the caller has to maintain the hash / HMAC state. Apart from this hash/HMAC state, no additional state is required to be maintained by either the caller or the KDF implementation. The key for the KDF is set with the crypto_kdf108_setkey function which is intended to be invoked before the caller requests a key derivation operation via crypto_kdf108_ctr_generate. SP800-108 allows the use of either a HMAC or a hash as crypto primitive for the KDF. When a HMAC primtive is intended to be used, crypto_kdf108_setkey must be used to set the HMAC key. Otherwise, for a hash crypto primitve crypto_kdf108_ctr_generate can be used immediately after allocating the hash handle. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
62 lines
2.1 KiB
C
62 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2021, Stephan Mueller <smueller@chronox.de>
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*/
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#ifndef _CRYPTO_KDF108_H
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#define _CRYPTO_KDF108_H
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#include <crypto/hash.h>
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#include <linux/uio.h>
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/**
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* Counter KDF generate operation according to SP800-108 section 5.1
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* as well as SP800-56A section 5.8.1 (Single-step KDF).
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*
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* @kmd Keyed message digest whose key was set with crypto_kdf108_setkey or
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* unkeyed message digest
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* @info optional context and application specific information - this may be
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* NULL
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* @info_vec number of optional context/application specific information entries
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* @dst destination buffer that the caller already allocated
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* @dlen length of the destination buffer - the KDF derives that amount of
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* bytes.
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*
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* To comply with SP800-108, the caller must provide Label || 0x00 || Context
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* in the info parameter.
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*
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* @return 0 on success, < 0 on error
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*/
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int crypto_kdf108_ctr_generate(struct crypto_shash *kmd,
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const struct kvec *info, unsigned int info_nvec,
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u8 *dst, unsigned int dlen);
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/**
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* Counter KDF setkey operation
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*
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* @kmd Keyed message digest allocated by the caller. The key should not have
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* been set.
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* @key Seed key to be used to initialize the keyed message digest context.
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* @keylen This length of the key buffer.
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* @ikm The SP800-108 KDF does not support IKM - this parameter must be NULL
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* @ikmlen This parameter must be 0.
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*
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* According to SP800-108 section 7.2, the seed key must be at least as large as
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* the message digest size of the used keyed message digest. This limitation
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* is enforced by the implementation.
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*
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* SP800-108 allows the use of either a HMAC or a hash primitive. When
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* the caller intends to use a hash primitive, the call to
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* crypto_kdf108_setkey is not required and the key derivation operation can
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* immediately performed using crypto_kdf108_ctr_generate after allocating
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* a handle.
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*
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* @return 0 on success, < 0 on error
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*/
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int crypto_kdf108_setkey(struct crypto_shash *kmd,
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const u8 *key, size_t keylen,
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const u8 *ikm, size_t ikmlen);
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#endif /* _CRYPTO_KDF108_H */
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