git.distorted.org.uk Git - u/mdw/catacomb/blob - pub/gdsa.h

   1 /* -*-c-*-
   2  *
   3  * Generalized version of DSA
   4  *
   5  * (c) 2004 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_GDSA_H
  29 #define CATACOMB_GDSA_H
  30
  31 #ifdef __cplusplus
  32   extern "C" {
  33 #endif
  34
  35 /*----- Header files ------------------------------------------------------*/
  36
  37 #ifndef CATACOMB_GHASH_H
  38 #  include "ghash.h"
  39 #endif
  40
  41 #ifndef CATACOMB_GROUP_H
  42 #  include "group.h"
  43 #endif
  44
  45 /*----- Data structures ---------------------------------------------------*/
  46
  47 /* --- GDSA context --- *
  48  *
  49  * You don't need to fill in all of this stuff.  See the description of the
  50  * function you want to use to find out what members are needed.
  51  */
  52
  53 typedef struct gdsa {
  54   group *g;                             /* The group we work in */
  55   mp *u;                                /* Private key, for signing */
  56   ge *p;                                /* Public key, for verifying */
  57   grand *r;                             /* Random number source */
  58   const gchash *h;                      /* Hash function */
  59 } gdsa;
  60
  61 /* --- GDSA signatures --- */
  62
  63 typedef struct gdsa_sig { mp *r, *s; } gdsa_sig;
  64 #define GDSA_SIG_INIT { MP_NEW, MP_NEW }
  65
  66 /*----- Functions provided ------------------------------------------------*/
  67
  68 /* --- @gdsa_beginhash@ --- *
  69  *
  70  * Arguments:   @const gdsa *c@ = pointer to the context structure
  71  *
  72  * Returns:     A hashing context for you to hash the message.
  73  *
  74  * Use:         Initializes a hash function correctly for you to hash a
  75  *              message.  Requires @h@.
  76  */
  77
  78 extern ghash *gdsa_beginhash(const gdsa */*c*/);
  79
  80 /* --- @gdsa_endhash@ --- *
  81  *
  82  * Arguments:   @const gdsa *c@ = pointer to the context structure
  83  *              @ghash *h@ = the hashing context
  84  *
  85  * Returns:     ---
  86  *
  87  * Use:         Does any final thing that DSA wants to do when hashing a
  88  *              message.  (Actually, there's nothing.)  The hashing context
  89  *              isn't finalized.
  90  */
  91
  92 extern void gdsa_endhash(const gdsa */*c*/, ghash */*h*/);
  93
  94 /* --- @gdsa_sign@ --- *
  95  *
  96  * Arguments:   @const gdsa *c@ = my context structure
  97  *              @gdsa_sig *s@ = where to put the signature (initialized)
  98  *              @const void *m@ = pointer to message hash
  99  *              @mp *k@ = random exponent for this message or null
 100  *
 101  * Returns:     ---
 102  *
 103  * Use:         Signs a message.  Requires @g@, @u@, @h@, and @r@ if @k@ is
 104  *              null.  This is a better idea than inventing @k@ yourself.
 105  */
 106
 107 extern void gdsa_sign(const gdsa */*c*/, gdsa_sig */*s*/,
 108                       const void */*m*/, mp */*k*/);
 109
 110 /* --- @gdsa_verify@ --- *
 111  *
 112  * Arguments:   @const gdsa *c@ = my context structure
 113  *              @const gdsa_sig *s@ = the signature to verify
 114  *              @const void *m@ = pointer to message hash
 115  *
 116  * Returns:     Zero if OK, negative on failure.
 117  *
 118  * Use:         Checks a signature on a message,  Requires @g@, @p@, @h@.
 119  */
 120
 121 extern int gdsa_verify(const gdsa */*c*/, const gdsa_sig */*s*/,
 122                        const void */*m*/);
 123
 124 /*----- That's all, folks -------------------------------------------------*/
 125
 126 #ifdef __cplusplus
 127   }
 128 #endif
 129
 130 #endif