_ Git - BearSSL/blob - src/ssl/ssl_keyexport.c

   1 /*
   2  * Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
   3  *
   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:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  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
  22  * SOFTWARE.
  23  */
  24
  25 #include "inner.h"
  26
  27 /*
  28  * Supported cipher suites that use SHA-384 for the PRF when selected
  29  * for TLS 1.2. All other cipher suites are deemed to use SHA-256.
  30  */
  31 static const uint16_t suites_sha384[] = {
  32         BR_TLS_RSA_WITH_AES_256_GCM_SHA384,
  33         BR_TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384,
  34         BR_TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384,
  35         BR_TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384,
  36         BR_TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384,
  37         BR_TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
  38         BR_TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384,
  39         BR_TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
  40         BR_TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384
  41 };
  42
  43 /* see bearssl_ssl.h */
  44 int
  45 br_ssl_key_export(br_ssl_engine_context *cc,
  46         void *dst, size_t len, const char *label,
  47         const void *context, size_t context_len)
  48 {
  49         br_tls_prf_seed_chunk chunks[4];
  50         br_tls_prf_impl iprf;
  51         size_t num_chunks, u;
  52         unsigned char tmp[2];
  53         int prf_id;
  54
  55         if (cc->application_data != 1) {
  56                 return 0;
  57         }
  58         chunks[0].data = cc->client_random;
  59         chunks[0].len = sizeof cc->client_random;
  60         chunks[1].data = cc->server_random;
  61         chunks[1].len = sizeof cc->server_random;
  62         if (context != NULL) {
  63                 br_enc16be(tmp, (unsigned)context_len);
  64                 chunks[2].data = tmp;
  65                 chunks[2].len = 2;
  66                 chunks[3].data = context;
  67                 chunks[3].len = context_len;
  68                 num_chunks = 4;
  69         } else {
  70                 num_chunks = 2;
  71         }
  72         prf_id = BR_SSLPRF_SHA256;
  73         for (u = 0; u < (sizeof suites_sha384) / sizeof(uint16_t); u ++) {
  74                 if (suites_sha384[u] == cc->session.cipher_suite) {
  75                         prf_id = BR_SSLPRF_SHA384;
  76                 }
  77         }
  78         iprf = br_ssl_engine_get_PRF(cc, prf_id);
  79         iprf(dst, len,
  80                 cc->session.master_secret, sizeof cc->session.master_secret,
  81                 label, num_chunks, chunks);
  82         return 1;
  83 }