2 * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files (the
6 * "Software"), to deal in the Software without restriction, including
7 * without limitation the rights to use, copy, modify, merge, publish,
8 * distribute, sublicense, and/or sell copies of the Software, and to
9 * permit persons to whom the Software is furnished to do so, subject to
10 * the following conditions:
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
27 const unsigned char br_hkdf_no_salt
= 0;
29 /* see bearssl_kdf.h */
31 br_hkdf_init(br_hkdf_context
*hc
, const br_hash_class
*digest_vtable
,
32 const void *salt
, size_t salt_len
)
34 br_hmac_key_context kc
;
35 unsigned char tmp
[64];
37 if (salt
== BR_HKDF_NO_SALT
) {
39 salt_len
= br_digest_size(digest_vtable
);
40 memset(tmp
, 0, salt_len
);
42 br_hmac_key_init(&kc
, digest_vtable
, salt
, salt_len
);
43 br_hmac_init(&hc
->u
.hmac_ctx
, &kc
, 0);
44 hc
->dig_len
= br_hmac_size(&hc
->u
.hmac_ctx
);
47 /* see bearssl_kdf.h */
49 br_hkdf_inject(br_hkdf_context
*hc
, const void *ikm
, size_t ikm_len
)
51 br_hmac_update(&hc
->u
.hmac_ctx
, ikm
, ikm_len
);
54 /* see bearssl_kdf.h */
56 br_hkdf_flip(br_hkdf_context
*hc
)
58 unsigned char tmp
[64];
60 br_hmac_out(&hc
->u
.hmac_ctx
, tmp
);
61 br_hmac_key_init(&hc
->u
.prk_ctx
,
62 br_hmac_get_digest(&hc
->u
.hmac_ctx
), tmp
, hc
->dig_len
);
63 hc
->ptr
= hc
->dig_len
;
67 /* see bearssl_kdf.h */
69 br_hkdf_produce(br_hkdf_context
*hc
,
70 const void *info
, size_t info_len
, void *out
, size_t out_len
)
78 if (hc
->ptr
== hc
->dig_len
) {
79 br_hmac_context hmac_ctx
;
83 if (hc
->chunk_num
== 256) {
87 br_hmac_init(&hmac_ctx
, &hc
->u
.prk_ctx
, 0);
89 br_hmac_update(&hmac_ctx
, hc
->buf
, hc
->dig_len
);
91 br_hmac_update(&hmac_ctx
, info
, info_len
);
92 br_hmac_update(&hmac_ctx
, &x
, 1);
93 br_hmac_out(&hmac_ctx
, hc
->buf
);
96 clen
= hc
->dig_len
- hc
->ptr
;
100 memcpy(out
, hc
->buf
+ hc
->ptr
, clen
);
101 out
= (unsigned char *)out
+ clen
;