text: /* SPDX-License-Identifier: GPL-2.0 */
  
  /*
   * Copyright (C) 2021, Stephan Mueller <smueller@chronox.de>
   */
  
  #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
   *	 NULL
   * @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 */
  