/* Copyright (c) (2014,2015,2017,2018,2019) Apple Inc. All rights reserved.
 *
 * corecrypto is licensed under Apple Inc.’s Internal Use License Agreement (which
 * is contained in the License.txt file distributed with corecrypto) and only to 
 * people who accept that license. IMPORTANT:  Any license rights granted to you by 
 * Apple Inc. (if any) are limited to internal use within your organization only on 
 * devices and computers you own or control, for the sole purpose of verifying the 
 * security characteristics and correct functioning of the Apple Software.  You may 
 * not, directly or indirectly, redistribute the Apple Software or any portions thereof.
 */

#ifndef _CORECRYPTO_CCHKDF_H_
#define _CORECRYPTO_CCHKDF_H_

#include <corecrypto/ccdigest.h>

/*!
    @function			cchkdf
    @abstract			Perform a NIST SP800-56C HKDF.
                        http://csrc.nist.gov/publications/nistpubs/800-56C/SP-800-56C.pdf
    @discussion			Derives output key data from input key data, optional salt, and info.

    @param di			Hash function to use.
    @param ikm_nbytes	Input key material length in bytes
    @param ikm			Input key material used to derive the new key
    @param salt_nbytes	Salt length length
    @param salt			Salt data
    @param info_nbytes	Info string length
    @param info			Info string
    @param dk_nbytes	Derived Key Length in bytes.
    @param dk			Derived key buffer to receive results of KDF
 */

int cchkdf(const struct ccdigest_info *di,
           size_t ikm_nbytes,
           const void *ikm,
           size_t salt_nbytes,
           const void *salt,
           size_t info_nbytes,
           const void *info,
           size_t dk_nbytes,
           void *dk);

/*!
    @function			cchkdf_extract
    @abstract			Perform a RFC5869-compliant HKDF-Extract
                        https://tools.ietf.org/html/rfc5869
    @discussion			Extract a pseudorandom key (PRK) from input keying material and a salt.

                        Note: In most cases, clients should use `cchkdf`. This function
                        is only exposed for specific use cases.

    @param di			Hash function to use.
    @param salt_nbytes	Salt length length
    @param salt			Salt data
    @param ikm_nbytes	Input key material length in bytes
    @param ikm			Input key material used to derive the new key
    @param prk			Pseudorandom Key (PRK) buffer to receive results of KDF, which must be equal
                        to the size of the hash function (di).
 */

int cchkdf_extract(const struct ccdigest_info *di,
                   size_t salt_nbytes,
                   const void *salt,
                   size_t ikm_nbytes,
                   const void *ikm,
                   void *prk);

/*!
    @function			cchkdf_expand
    @abstract			Perform a RFC5869-compliant HKDF-Expand
                        https://tools.ietf.org/html/rfc5869
    @discussion			Expands input keying material to the desired length, using the according
   info.

                        Note: In most cases, clients should use `cchkdf`. This function
                        is only exposed for specific use cases.

    @param di			Hash function to use.
    @param ikm_nbytes	Input key material length in bytes
    @param ikm			Input key material used to derive the new key
    @param info_nbytes	Info string length
    @param info			Info string
    @param dk_nbytes	Derived Key Length in bytes.
    @param dk			Derived key buffer to receive results of KDF
 */

int cchkdf_expand(const struct ccdigest_info *di,
                  size_t ikm_nbytes,
                  const void *ikm,
                  size_t info_nbytes,
                  const void *info,
                  size_t dk_nbytes,
                  void *dk);

#endif /* _CORECRYPTO_CCHKDF_H_ */
