mdw@git.distorted.org.uk Git - secnet/blob - x448.h

   1 /* -*-c-*-
   2  *
   3  * The X448 key-agreement algorithm
   4  *
   5  * (c) 2017 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of secnet.
  11  * See README for full list of copyright holders.
  12  *
  13  * secnet is free software; you can redistribute it and/or modify it
  14  * under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version d of the License, or
  16  * (at your option) any later version.
  17  *
  18  * secnet is distributed in the hope that it will be useful, but
  19  * WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21  * General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * version 3 along with secnet; if not, see
  25  * https://www.gnu.org/licenses/gpl.html.
  26  *
  27  * This file was originally part of Catacomb, but has been automatically
  28  * modified for incorporation into secnet: see `import-catacomb-crypto'
  29  * for details.
  30  *
  31  * Catacomb is free software; you can redistribute it and/or modify
  32  * it under the terms of the GNU Library General Public License as
  33  * published by the Free Software Foundation; either version 2 of the
  34  * License, or (at your option) any later version.
  35  *
  36  * Catacomb is distributed in the hope that it will be useful,
  37  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  38  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  39  * GNU Library General Public License for more details.
  40  *
  41  * You should have received a copy of the GNU Library General Public
  42  * License along with Catacomb; if not, write to the Free
  43  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  44  * MA 02111-1307, USA.
  45  */
  46
  47 #ifndef CATACOMB_X448_H
  48 #define CATACOMB_X448_H
  49
  50 #ifdef __cplusplus
  51   extern "C" {
  52 #endif
  53
  54 /*----- Notes on the X448 key-agreement algorithm -------------------------*
  55  *
  56  * This is X448, as described in RFC7748, based on the elliptic curve defined
  57  * in Mike Hamburg, `Ed448-Goldilocks, a new elliptic curve', EUROCRYPT 2016,
  58  * https://eprint.iacr.org/2015/625/.  (The curve here is 4-isogenous to
  59  * Hamburg's curve.)
  60  *
  61  * The RFC-specified operation is simpler than the Diffie--Hellman function
  62  * described in Hamburg's paper, since it doesn't involve the `Decaf'
  63  * cofactor elimination procedure.  Indeed, it looks very much like X25519
  64  * with Hamburg's curve slotted in in place of Bernstein's.
  65  */
  66
  67 /*----- Header files ------------------------------------------------------*/
  68
  69 #include "fake-mLib-bits.h"
  70
  71 /*----- Important constants -----------------------------------------------*/
  72
  73 #define X448_KEYSZ 56
  74 #define X448_PUBSZ 56
  75 #define X448_OUTSZ 56
  76
  77 extern const octet x448_base[56];
  78
  79 /*----- Functions provided ------------------------------------------------*/
  80
  81 /* --- @x448@ --- *
  82  *
  83  * Arguments:   @octet zz[X448_OUTSZ]@ = where to put the result
  84  *              @const octet k[X448_KEYSZ]@ = pointer to private key
  85  *              @const octet qx[X448_PUBSZ]@ = pointer to public value
  86  *
  87  * Returns:     ---
  88  *
  89  * Use:         Calculates X448 of @k@ and @qx@.
  90  */
  91
  92 extern void x448(octet /*zz*/[X448_OUTSZ],
  93                  const octet /*k*/[X448_KEYSZ],
  94                  const octet /*qx*/[X448_PUBSZ]);
  95
  96 /*----- That's all, folks -------------------------------------------------*/
  97
  98 #ifdef __cplusplus
  99   }
 100 #endif
 101
 102 #endif