1/* Copyright (c) 2014, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15#ifndef OPENSSL_HEADER_HKDF_H
16#define OPENSSL_HEADER_HKDF_H
17
18#include <openssl/base.h>
19
20#if defined(__cplusplus)
21extern "C" {
22#endif
23
24
25// HKDF.
26
27
28// HKDF computes HKDF (as specified by RFC 5869) of initial keying material
29// |secret| with |salt| and |info| using |digest|, and outputs |out_len| bytes
30// to |out_key|. It returns one on success and zero on error.
31//
32// HKDF is an Extract-and-Expand algorithm. It does not do any key stretching,
33// and as such, is not suited to be used alone to generate a key from a
34// password.
35OPENSSL_EXPORT int HKDF(uint8_t *out_key, size_t out_len, const EVP_MD *digest,
36 const uint8_t *secret, size_t secret_len,
37 const uint8_t *salt, size_t salt_len,
38 const uint8_t *info, size_t info_len);
39
40// HKDF_extract computes a HKDF PRK (as specified by RFC 5869) from initial
41// keying material |secret| and salt |salt| using |digest|, and outputs
42// |out_len| bytes to |out_key|. The maximum output size is |EVP_MAX_MD_SIZE|.
43// It returns one on success and zero on error.
44OPENSSL_EXPORT int HKDF_extract(uint8_t *out_key, size_t *out_len,
45 const EVP_MD *digest, const uint8_t *secret,
46 size_t secret_len, const uint8_t *salt,
47 size_t salt_len);
48
49// HKDF_expand computes a HKDF OKM (as specified by RFC 5869) of length
50// |out_len| from the PRK |prk| and info |info| using |digest|, and outputs
51// the result to |out_key|. It returns one on success and zero on error.
52OPENSSL_EXPORT int HKDF_expand(uint8_t *out_key, size_t out_len,
53 const EVP_MD *digest, const uint8_t *prk,
54 size_t prk_len, const uint8_t *info,
55 size_t info_len);
56
57
58#if defined(__cplusplus)
59} // extern C
60#endif
61
62#define HKDF_R_OUTPUT_TOO_LARGE 100
63
64#endif // OPENSSL_HEADER_HKDF_H
65