mdw@git.distorted.org.uk Git - catacomb/blob - pub/ed25519.h

   1 /* -*-c-*-
   2  *
   3  * The Ed25519 signature scheme
   4  *
   5  * (c) 2017 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 #ifndef CATACOMB_ED25519_H
  29 #define CATACOMB_ED25519_H
  30
  31 #ifdef __cplusplus
  32   extern "C" {
  33 #endif
  34
  35 /*----- Notes on the Ed25519 signature scheme -----------------------------*
  36  *
  37  * This is Ed25519, as described in Daniel J. Bernstein, Neils Duif, Tanja
  38  * Lange, Peter Schwabe, and Bo-Yin Yang, `High-speed high-security
  39  * signatures', CHES 2011, https://ed25519.cr.yp.to/ed25519-20110926.pdf
  40  *
  41  * Specifically, this code implements `PureEdDSA', according to the
  42  * definition in Daniel J. Bernstein, Simon Josefsson, Tanja Lange, Peter
  43  * Schwabe, and Bo-Yin Yang, `EdDSA for more curves',
  44  * https://ed25519.cr.yp.to/eddsa-20150704.pdf.  HashEdEDSA can be
  45  * implemented easily by presenting a hash of a message to the functions
  46  * here, as the message to be signed or verified.
  47  */
  48
  49 /*----- Header files ------------------------------------------------------*/
  50
  51 #include <mLib/bits.h>
  52
  53 #ifndef CATACOMB_KEY_H
  54 #  include "key.h"
  55 #endif
  56
  57 /*----- Important constants -----------------------------------------------*/
  58
  59 #define ED25519_KEYSZ 32u
  60 #define ED25519_PUBSZ 32u
  61 #define ED25519_SIGSZ 64u
  62
  63 /*----- Key fetching ------------------------------------------------------*/
  64
  65 typedef struct ed25519_priv { key_bin priv, pub; } ed25519_priv;
  66 typedef struct ed25519_pub { key_bin pub; } ed25519_pub;
  67
  68 extern const key_fetchdef ed25519_pubfetch[], ed25519_privfetch[];
  69 #define ED25519_PUBFETCHSZ 3
  70 #define ED25519_PRIVFETCHSZ 6
  71
  72 /*----- Functions provided ------------------------------------------------*/
  73
  74 /* --- @ed25519_pubkey@ --- *
  75  *
  76  * Arguments:   @octet K[ED25519_PUBSZ]@ = where to put the public key
  77  *              @const void *k@ = private key
  78  *              @size_t ksz@ = length of private key
  79  *
  80  * Returns:     ---
  81  *
  82  * Use:         Derives the public key from a private key.
  83  */
  84
  85 extern void ed25519_pubkey(octet /*K*/[ED25519_PUBSZ],
  86                            const void */*k*/, size_t /*ksz*/);
  87
  88 /* --- @ed25519_sign@ --- *
  89  *
  90  * Arguments:   @octet sig[ED25519_SIGSZ]@ = where to put the signature
  91  *              @const void *k@ = private key
  92  *              @size_t ksz@ = length of private key
  93  *              @const octet K[ED25519_PUBSZ]@ = public key
  94  *              @const void *m@ = message to sign
  95  *              @size_t msz@ = length of message
  96  *
  97  * Returns:     ---
  98  *
  99  * Use:         Signs a message.
 100  */
 101
 102 extern void ed25519_sign(octet /*sig*/[ED25519_SIGSZ],
 103                          const void */*k*/, size_t /*ksz*/,
 104                          const octet /*K*/[ED25519_PUBSZ],
 105                          const void */*m*/, size_t /*msz*/);
 106
 107 /* --- @ed25519_verify@ --- *
 108  *
 109  * Arguments:   @const octet K[ED25519_PUBSZ]@ = public key
 110  *              @const void *m@ = message to sign
 111  *              @size_t msz@ = length of message
 112  *              @const octet sig[ED25519_SIGSZ]@ = signature
 113  *
 114  * Returns:     Zero if OK, negative on failure.
 115  *
 116  * Use:         Verify a signature.
 117  */
 118
 119 extern int ed25519_verify(const octet /*K*/[ED25519_PUBSZ],
 120                           const void */*m*/, size_t /*msz*/,
 121                           const octet /*sig*/[ED25519_SIGSZ]);
 122
 123 /*----- That's all, folks -------------------------------------------------*/
 124
 125 #ifdef __cplusplus
 126   }
 127 #endif
 128
 129 #endif