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/* $OpenBSD: hkdf.h,v 1.2 2018/04/03 13:33:53 tb Exp $ */
/* Copyright (c) 2014, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#ifndef OPENSSL_HEADER_HKDF_H
#define OPENSSL_HEADER_HKDF_H
#include <openssl/evp.h>
#if defined(__cplusplus)
extern "C" {
#endif
/*
* HKDF computes HKDF (as specified by RFC 5869) of initial keying
* material |secret| with |salt| and |info| using |digest|, and
* outputs |out_len| bytes to |out_key|. It returns one on success and
* zero on error.
*
* HKDF is an Extract-and-Expand algorithm. It does not do any key
* stretching, and as such, is not suited to be used alone to generate
* a key from a password.
*/
int HKDF(uint8_t *out_key, size_t out_len, const struct env_md_st *digest,
const uint8_t *secret, size_t secret_len, const uint8_t *salt,
size_t salt_len, const uint8_t *info, size_t info_len);
/*
* HKDF_extract computes a HKDF PRK (as specified by RFC 5869) from
* initial keying material |secret| and salt |salt| using |digest|,
* and outputs |out_len| bytes to |out_key|. The maximum output size
* is |EVP_MAX_MD_SIZE|. It returns one on success and zero on error.
*/
int HKDF_extract(uint8_t *out_key, size_t *out_len,
const struct env_md_st *digest, const uint8_t *secret,
size_t secret_len, const uint8_t *salt, size_t salt_len);
/*
* HKDF_expand computes a HKDF OKM (as specified by RFC 5869) of
* length |out_len| from the PRK |prk| and info |info| using |digest|,
* and outputs the result to |out_key|. It returns one on success and
* zero on error.
*/
int HKDF_expand(uint8_t *out_key, size_t out_len,
const EVP_MD *digest, const uint8_t *prk, size_t prk_len,
const uint8_t *info, size_t info_len);
#if defined(__cplusplus)
} /* extern C */
#endif
#endif /* OPENSSL_HEADER_HKDF_H */
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