git.distorted.org.uk Git - u/mdw/catacomb/blob - group-parse.c

   1 /* -*-c-*-
   2  *
   3  * $Id: group-parse.c,v 1.1 2004/04/01 12:50:09 mdw Exp $
   4  *
   5  * Parse group description strings
   6  *
   7  * (c) 2004 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Trivial IP Encryption (TrIPE).
  13  *
  14  * TrIPE is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * TrIPE 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 General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with TrIPE; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: group-parse.c,v $
  32  * Revision 1.1  2004/04/01 12:50:09  mdw
  33  * Add cyclic group abstraction, with test code.  Separate off exponentation
  34  * functions for better static linking.  Fix a buttload of bugs on the way.
  35  * Generally ensure that negative exponents do inversion correctly.  Add
  36  * table of standard prime-field subgroups.  (Binary field subgroups are
  37  * currently unimplemented but easy to add if anyone ever finds a good one.)
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include "group.h"
  44 #include "dh.h"
  45
  46 /*----- Main code ---------------------------------------------------------*/
  47
  48 /* --- @group_parse@ --- *
  49  *
  50  * Arguments:   @qd_parse *qd@ = quick-and-dirty parser
  51  *
  52  * Returns:     Group pointer, or null for failure.
  53  *
  54  * Use:         Parses a group description and returns the group.  This has
  55  *              the form `TYPE { SPEC }' where TYPE is `prime' or `ec', and
  56  *              SPEC is the appropriate kind of group specification of the
  57  *              given type.
  58  */
  59
  60 group *group_parse(qd_parse *qd)
  61 {
  62   group *g = 0;
  63
  64   switch (qd_enum(qd, "prime,ec")) {
  65     case 0: {
  66       dh_param dp;
  67       qd_delim(qd, '{');
  68       if (dh_parse(qd, &dp)) break;
  69       qd_delim(qd, '}');
  70       g = group_prime(&dp);
  71       dh_paramfree(&dp);
  72     } break;
  73     case 1: {
  74       ec_info ei;
  75       qd_delim(qd, '{');
  76       if (ec_infoparse(qd, &ei)) break;
  77       qd_delim(qd, '}');
  78       g = group_ec(&ei);
  79     } break;
  80   }
  81   return (g);
  82 }
  83
  84 /* --- @group_fromstring@ --- *
  85  *
  86  * Arguments:   @const char *p@ = pointer to string to read
  87  *              @group **gg@ = where to put the group pointer
  88  *
  89  * Returns:     Null if OK, or an error string.
  90  *
  91  * Use:         Parses a group spec from a string, and returns the group.
  92  */
  93
  94 const char *group_fromstring(const char *p, group **gg)
  95 {
  96   group *g;
  97   qd_parse qd;
  98
  99   qd.p = p;
 100   qd.e = 0;
 101   if ((g = group_parse(&qd)) == 0) return (qd.e);
 102   if (!qd_eofp(&qd)) { G_DESTROYGROUP(g); return ("junk at end of string"); }
 103   *gg = g;
 104   return (0);
 105 }
 106
 107 /*----- That's all, folks -------------------------------------------------*/