_ Git - BearSSL/blob - src/ec/ec_pubkey.c

   1 /*
   2  * Copyright (c) 2018 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 static const unsigned char POINT_LEN[] = {
  28           0,   /* 0: not a valid curve ID */
  29          43,   /* sect163k1 */
  30          43,   /* sect163r1 */
  31          43,   /* sect163r2 */
  32          51,   /* sect193r1 */
  33          51,   /* sect193r2 */
  34          61,   /* sect233k1 */
  35          61,   /* sect233r1 */
  36          61,   /* sect239k1 */
  37          73,   /* sect283k1 */
  38          73,   /* sect283r1 */
  39         105,   /* sect409k1 */
  40         105,   /* sect409r1 */
  41         145,   /* sect571k1 */
  42         145,   /* sect571r1 */
  43          41,   /* secp160k1 */
  44          41,   /* secp160r1 */
  45          41,   /* secp160r2 */
  46          49,   /* secp192k1 */
  47          49,   /* secp192r1 */
  48          57,   /* secp224k1 */
  49          57,   /* secp224r1 */
  50          65,   /* secp256k1 */
  51          65,   /* secp256r1 */
  52          97,   /* secp384r1 */
  53         133,   /* secp521r1 */
  54          65,   /* brainpoolP256r1 */
  55          97,   /* brainpoolP384r1 */
  56         129,   /* brainpoolP512r1 */
  57          32,   /* curve25519 */
  58          56,   /* curve448 */
  59 };
  60
  61 /* see bearssl_ec.h */
  62 size_t
  63 br_ec_compute_pub(const br_ec_impl *impl, br_ec_public_key *pk,
  64         void *kbuf, const br_ec_private_key *sk)
  65 {
  66         int curve;
  67         size_t len;
  68
  69         curve = sk->curve;
  70         if (curve < 0 || curve >= 32 || curve >= (int)(sizeof POINT_LEN)
  71                 || ((impl->supported_curves >> curve) & 1) == 0)
  72         {
  73                 return 0;
  74         }
  75         if (kbuf == NULL) {
  76                 return POINT_LEN[curve];
  77         }
  78         len = impl->mulgen(kbuf, sk->x, sk->xlen, curve);
  79         if (pk != NULL) {
  80                 pk->curve = curve;
  81                 pk->q = kbuf;
  82                 pk->qlen = len;
  83         }
  84         return len;
  85 }