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