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

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Generalized version of KCDSA
   6  *
   7  * (c) 2004 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 #ifndef CATACOMB_GKCDSA_H
  31 #define CATACOMB_GKCDSA_H
  32
  33 #ifdef __cplusplus
  34   extern "C" {
  35 #endif
  36
  37 /*----- Header files ------------------------------------------------------*/
  38
  39 #ifndef CATACOMB_GROUP_H
  40 #  include "group.h"
  41 #endif
  42
  43 #ifndef CATACOMB_GHASH_H
  44 #  include "ghash.h"
  45 #endif
  46
  47 #ifndef CATACOMB_GDSA_H
  48 #  include "gdsa.h"
  49 #endif
  50
  51 /*----- Data structures ---------------------------------------------------*/
  52
  53 /* --- Careful! --- *
  54  *
  55  * These structures are the same as for DSA.  However, the private key @u@ is
  56  * the %$\emph{inverse}$% of the exponent.  Do this wrong and the maths will
  57  * fail hopelessly.
  58  */
  59
  60 typedef gdsa gkcdsa;
  61
  62 typedef struct gkcdsa_sig {
  63   octet *r;                             /* Null means @xmalloc@ me */
  64   mp *s;
  65 } gkcdsa_sig;
  66 #define GKCDSA_SIG_INIT { 0, 0 }
  67
  68 /*----- Functions provided ------------------------------------------------*/
  69
  70 /* --- @gkcdsa_beginhash@ --- *
  71  *
  72  * Arguments:   @const gkcdsa *c@ = pointer to the context structure
  73  *
  74  * Returns:     A hashing context for you to hash the message.
  75  *
  76  * Use:         Initializes a hash function correctly for you to hash a
  77  *              message.  Requires @h@, @g@ and @p@.
  78  */
  79
  80 extern ghash *gkcdsa_beginhash(const gkcdsa */*c*/);
  81
  82 /* --- @gkcdsa_endhash@ --- *
  83  *
  84  * Arguments:   @const gkcdsa *c@ = pointer to the context structure
  85  *              @ghash *h@ = the hashing context
  86  *
  87  * Returns:     ---
  88  *
  89  * Use:         Does any final thing that KCDSA wants to do when hashing a
  90  *              message.  (Actually, there's nothing.)  The hashing context
  91  *              isn't finalized.
  92  */
  93
  94 extern void gkcdsa_endhash(const gkcdsa */*c*/, ghash */*h*/);
  95
  96 /* --- @gkcdsa_sign@ --- *
  97  *
  98  * Arguments:   @const gkcdsa *c@ = my context structure
  99  *              @gkcdsa_sig *s@ = where to put the signature (initialized)
 100  *              @const void *m@ = pointer to message hash
 101  *              @mp *k@ = random exponent for this message or null
 102  *
 103  * Returns:     ---
 104  *
 105  * Use:         Signs a message.  Requires @g@, @u@, @h@, and @r@ if @k@ is
 106  *              null.  This is a better idea than inventing @k@ yourself.
 107  */
 108
 109 extern void gkcdsa_sign(const gkcdsa */*c*/, gkcdsa_sig */*s*/,
 110                         const void */*m*/, mp */*k*/);
 111
 112 /* --- @gkcdsa_verify@ --- *
 113  *
 114  * Arguments:   @const gkcdsa *c@ = my context structure
 115  *              @const gkcdsa_sig *s@ = the signature to verify
 116  *              @const void *m@ = pointer to message hash
 117  *
 118  * Returns:     Zero if OK, negative on failure.
 119  *
 120  * Use:         Checks a signature on a message,  Requires @g@, @p@, @h@.
 121  */
 122
 123 extern int gkcdsa_verify(const gkcdsa */*c*/, const gkcdsa_sig */*s*/,
 124                          const void */*m*/);
 125
 126 /*----- That's all, folks -------------------------------------------------*/
 127
 128 #ifdef __cplusplus
 129   }
 130 #endif
 131
 132 #endif