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

   1 /* -*-c-*-
   2  *
   3  * $Id: group-parse.c,v 1.2 2004/04/03 03:32:05 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 1.2  2004/04/03 03:32:05  mdw
  33  * General robustification.
  34  *
  35  * Revision 1.1  2004/04/01 12:50:09  mdw
  36  * Add cyclic group abstraction, with test code.  Separate off exponentation
  37  * functions for better static linking.  Fix a buttload of bugs on the way.
  38  * Generally ensure that negative exponents do inversion correctly.  Add
  39  * table of standard prime-field subgroups.  (Binary field subgroups are
  40  * currently unimplemented but easy to add if anyone ever finds a good one.)
  41  *
  42  */
  43
  44 /*----- Header files ------------------------------------------------------*/
  45
  46 #include "group.h"
  47 #include "dh.h"
  48
  49 /*----- Main code ---------------------------------------------------------*/
  50
  51 /* --- @group_parse@ --- *
  52  *
  53  * Arguments:   @qd_parse *qd@ = quick-and-dirty parser
  54  *
  55  * Returns:     Group pointer, or null for failure.
  56  *
  57  * Use:         Parses a group description and returns the group.  This has
  58  *              the form `TYPE { SPEC }' where TYPE is `prime' or `ec', and
  59  *              SPEC is the appropriate kind of group specification of the
  60  *              given type.
  61  */
  62
  63 group *group_parse(qd_parse *qd)
  64 {
  65   group *g = 0;
  66
  67   switch (qd_enum(qd, "prime,ec")) {
  68     case 0: {
  69       dh_param dp;
  70       qd_delim(qd, '{');
  71       if (dh_parse(qd, &dp)) break;
  72       qd_delim(qd, '}');
  73       g = group_prime(&dp);
  74       dh_paramfree(&dp);
  75     } break;
  76     case 1: {
  77       ec_info ei;
  78       qd_delim(qd, '{');
  79       if (ec_infoparse(qd, &ei)) break;
  80       qd_delim(qd, '}');
  81       g = group_ec(&ei);
  82     } break;
  83   }
  84   if (!g) qd->e = "bad group parameters";
  85   return (g);
  86 }
  87
  88 /* --- @group_fromstring@ --- *
  89  *
  90  * Arguments:   @const char *p@ = pointer to string to read
  91  *              @group **gg@ = where to put the group pointer
  92  *
  93  * Returns:     Null if OK, or an error string.
  94  *
  95  * Use:         Parses a group spec from a string, and returns the group.
  96  */
  97
  98 const char *group_fromstring(const char *p, group **gg)
  99 {
 100   group *g;
 101   qd_parse qd;
 102
 103   qd.p = p;
 104   qd.e = 0;
 105   if ((g = group_parse(&qd)) == 0) return (qd.e);
 106   if (!qd_eofp(&qd)) { G_DESTROYGROUP(g); return ("junk at end of string"); }
 107   *gg = g;
 108   return (0);
 109 }
 110
 111 /*----- That's all, folks -------------------------------------------------*/