git.distorted.org.uk Git - u/mdw/catacomb/blob - f-binpoly.c

   1 /* -*-c-*-
   2  *
   3  * $Id: f-binpoly.c,v 1.4 2004/03/23 15:19:32 mdw Exp $
   4  *
   5  * Binary fields with polynomial basis representation
   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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: f-binpoly.c,v $
  33  * Revision 1.4  2004/03/23 15:19:32  mdw
  34  * Test elliptic curves more thoroughly.
  35  *
  36  * Revision 1.3  2004/03/23 12:08:26  mdw
  37  * Random field-element selection.
  38  *
  39  * Revision 1.2  2004/03/21 22:52:06  mdw
  40  * Merge and close elliptic curve branch.
  41  *
  42  * Revision 1.1.2.1  2004/03/21 22:39:46  mdw
  43  * Elliptic curves on binary fields work.
  44  *
  45  */
  46
  47 /*----- Header files ------------------------------------------------------*/
  48
  49 #include <mLib/sub.h>
  50
  51 #include "field.h"
  52 #include "gf.h"
  53 #include "gfreduce.h"
  54 #include "mprand.h"
  55
  56 /*----- Data structures ---------------------------------------------------*/
  57
  58 typedef struct fctx {
  59   field f;
  60   gfreduce r;
  61 } fctx;
  62
  63 /*----- Main code ---------------------------------------------------------*/
  64
  65 /* --- Field operations --- */
  66
  67 static void fdestroy(field *ff)
  68 {
  69   fctx *f = (fctx *)ff;
  70   gfreduce_destroy(&f->r);
  71   DESTROY(f);
  72 }
  73
  74 static mp *frand(field *ff, mp *d, grand *r)
  75 {
  76   fctx *f = (fctx *)ff;
  77   return (mprand(d, mp_octets(f->r.p) - 1, r, 0));
  78 }
  79
  80 static int fzerop(field *ff, mp *x)
  81 {
  82   return (!MP_LEN(x));
  83 }
  84
  85 static mp *fadd(field *ff, mp *d, mp *x, mp *y)
  86 {
  87   return (gf_add(d, x, y));
  88 }
  89
  90 static mp *fmul(field *ff, mp *d, mp *x, mp *y)
  91 {
  92   fctx *f = (fctx *)ff;
  93   d = gf_mul(d, x, y);
  94   return (gfreduce_do(&f->r, d, d));
  95 }
  96
  97 static mp *fsqr(field *ff, mp *d, mp *x)
  98 {
  99   fctx *f = (fctx *)ff;
 100   d = gf_sqr(d, x);
 101   return (gfreduce_do(&f->r, d, d));
 102 }
 103
 104 static mp *finv(field *ff, mp *d, mp *x)
 105 {
 106   fctx *f = (fctx *)ff;
 107   gf_gcd(0, 0, &d, f->r.p, x);
 108   return (d);
 109 }
 110
 111 static mp *freduce(field *ff, mp *d, mp *x)
 112 {
 113   fctx *f = (fctx *)ff;
 114   return (gfreduce_do(&f->r, d, x));
 115 }
 116
 117 static mp *fsqrt(field *ff, mp *d, mp *x)
 118 {
 119   fctx *f = (fctx *)ff;
 120   return (gfreduce_sqrt(&f->r, d, x));
 121 }
 122
 123 static mp *fquadsolve(field *ff, mp *d, mp *x)
 124 {
 125   fctx *f = (fctx *)ff;
 126   return (gfreduce_quadsolve(&f->r, d, x));
 127 }
 128
 129 /* --- Field operations table --- */
 130
 131 static field_ops fops = {
 132   FTY_BINARY, "binpoly",
 133   fdestroy, frand,
 134   freduce, field_id,
 135   fzerop, field_id, fadd, fadd, fmul, fsqr, finv, freduce, fsqrt,
 136   fquadsolve,
 137   0, 0, 0, 0
 138 };
 139
 140 /* --- @field_binpoly@ --- *
 141  *
 142  * Arguments:   @mp *p@ = the reduction polynomial
 143  *
 144  * Returns:     A pointer to the field.
 145  *
 146  * Use:         Creates a field structure for a binary field mod @p@.
 147  */
 148
 149 field *field_binpoly(mp *p)
 150 {
 151   fctx *f = CREATE(fctx);
 152   f->f.ops = &fops;
 153   f->f.zero = MP_ZERO;
 154   f->f.one = MP_ONE;
 155   gfreduce_create(&f->r, p);
 156   return (&f->f);
 157 }
 158
 159 /*----- That's all, folks -------------------------------------------------*/