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

   1 /* -*-c-*-
   2  *
   3  * $Id: field.h,v 1.7 2004/03/27 00:04:46 mdw Exp $
   4  *
   5  * Definitions for field arithmetic
   6  *
   7  * (c) 2000 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: field.h,v $
  33  * Revision 1.7  2004/03/27 00:04:46  mdw
  34  * Implement efficient reduction for pleasant-looking primes.
  35  *
  36  * Revision 1.6  2004/03/23 15:19:32  mdw
  37  * Test elliptic curves more thoroughly.
  38  *
  39  * Revision 1.5  2004/03/23 12:08:26  mdw
  40  * Random field-element selection.
  41  *
  42  * Revision 1.4  2004/03/21 22:52:06  mdw
  43  * Merge and close elliptic curve branch.
  44  *
  45  * Revision 1.3.4.2  2004/03/21 22:39:46  mdw
  46  * Elliptic curves on binary fields work.
  47  *
  48  * Revision 1.3.4.1  2004/03/20 00:13:31  mdw
  49  * Projective coordinates for prime curves
  50  *
  51  * Revision 1.3  2002/01/13 13:48:44  mdw
  52  * Further progress.
  53  *
  54  * Revision 1.2  2001/05/07 17:30:13  mdw
  55  * Add an internal-representation no-op function.
  56  *
  57  * Revision 1.1  2001/04/29 18:12:33  mdw
  58  * Prototype version.
  59  *
  60  */
  61
  62 #ifndef CATACOMB_FIELD_H
  63 #define CATACOMB_FIELD_H
  64
  65 #ifdef __cplusplus
  66   extern "C" {
  67 #endif
  68
  69 /*----- Header files ------------------------------------------------------*/
  70
  71 #ifndef CATACOMB_GRAND_H
  72 #  include "grand.h"
  73 #endif
  74
  75 #ifndef CATACOMB_MP_H
  76 #  include "mp.h"
  77 #endif
  78
  79 /*----- Data structures ---------------------------------------------------*/
  80
  81 typedef struct field {
  82   const struct field_ops *ops;          /* Field operations */
  83   mp *zero, *one;                       /* Identities in the field */
  84 } field;
  85
  86 enum {
  87   FTY_PRIME,
  88   FTY_BINARY
  89 };
  90
  91 typedef struct field_ops {
  92
  93   /* --- General information --- */
  94
  95   unsigned ty;                          /* What kind of field this is */
  96   const char *name;                     /* Human-readable name string */
  97
  98   /* --- Universal operations --- */
  99
 100   void (*destroy)(field */*f*/);
 101   mp *(*rand)(field */*f*/, mp */*d*/, grand */*r*/);
 102
 103   mp *(*in)(field */*f*/, mp */*d*/, mp */*x*/);
 104   mp *(*out)(field */*f*/, mp */*d*/, mp */*x*/);
 105
 106   int (*zerop)(field */*f*/, mp */*x*/);
 107   mp *(*neg)(field */*f*/, mp */*d*/, mp */*x*/);
 108   mp *(*add)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
 109   mp *(*sub)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
 110   mp *(*mul)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
 111   mp *(*sqr)(field */*f*/, mp */*d*/, mp */*x*/);
 112   mp *(*inv)(field */*f*/, mp */*d*/, mp */*x*/);
 113   mp *(*reduce)(field */*f*/, mp */*d*/, mp */*x*/);
 114   mp *(*sqrt)(field */*f*/, mp */*d*/, mp */*x*/);
 115
 116   /* --- Operations for binary fields only --- */
 117
 118   mp *(*quadsolve)(field */*f*/, mp */*d*/, mp */*x*/);
 119
 120   /* --- Operations for prime fields only --- */
 121
 122   mp *(*dbl)(field */*f*/, mp */*d*/, mp */*x*/);
 123   mp *(*tpl)(field */*f*/, mp */*d*/, mp */*x*/);
 124   mp *(*qdl)(field */*f*/, mp */*d*/, mp */*x*/);
 125   mp *(*hlv)(field */*f*/, mp */*d*/, mp */*x*/);
 126
 127 } field_ops;
 128
 129 #define F_TYPE(f)               (f)->ops->ty
 130 #define F_NAME(f)               (f)->ops->name
 131
 132 #define F_DESTROY(f)            (f)->ops->destroy((f))
 133 #define F_RAND(f, d, r)         (f)->ops->rand((f), (d), (r))
 134
 135 #define F_IN(f, d, x)           (f)->ops->in((f), (d), (x))
 136 #define F_OUT(f, d, x)          (f)->ops->out((f), (d), (x))
 137
 138 #define F_ZEROP(f, x)           (f)->ops->zerop((f), (x))
 139 #define F_NEG(f, d, x)          (f)->ops->neg((f), (d), (x))
 140 #define F_ADD(f, d, x, y)       (f)->ops->add((f), (d), (x), (y))
 141 #define F_SUB(f, d, x, y)       (f)->ops->sub((f), (d), (x), (y))
 142 #define F_MUL(f, d, x, y)       (f)->ops->mul((f), (d), (x), (y))
 143 #define F_SQR(f, d, x)          (f)->ops->sqr((f), (d), (x))
 144 #define F_INV(f, d, x)          (f)->ops->inv((f), (d), (x))
 145 #define F_REDUCE(f, d, x)       (f)->ops->reduce((f), (d), (x))
 146 #define F_SQRT(f, d, x)         (f)->ops->sqrt((f), (d), (x))
 147
 148 #define F_QUADSOLVE(f, d, x)    (f)->ops->quadsolve((f), (d), (x))
 149
 150 #define F_DBL(f, d, x)          (f)->ops->dbl((f), (d), (x))
 151 #define F_TPL(f, d, x)          (f)->ops->tpl((f), (d), (x))
 152 #define F_QDL(f, d, x)          (f)->ops->qdl((f), (d), (x))
 153 #define F_HLV(f, d, x)          (f)->ops->hlv((f), (d), (x))
 154
 155 /*----- Helpful field operations ------------------------------------------*/
 156
 157 /* --- @field_id@ --- *
 158  *
 159  * Arguments:   @field *f@ = pointer to a field
 160  *              @mp *d@ = a destination element
 161  *              @mp *x@ = a source element
 162  *
 163  * Returns:     The result element.
 164  *
 165  * Use:         An identity operation which can be used if your field has no
 166  *              internal representation.
 167  */
 168
 169 extern mp *field_id(field */*f*/, mp */*d*/, mp */*x*/);
 170
 171 /*----- Creating fields ---------------------------------------------------*/
 172
 173 /* --- @field_prime@ --- *
 174  *
 175  * Arguments:   @mp *p@ = the characteristic of the field
 176  *
 177  * Returns:     A pointer to the field.
 178  *
 179  * Use:         Creates a field structure for a prime field of size %$p$%,
 180  *              using Montgomery reduction for arithmetic.
 181  */
 182
 183 extern field *field_prime(mp */*p*/);
 184
 185 /* --- @field_niceprime@ --- *
 186  *
 187  * Arguments:   @mp *p@ = the characteristic of the field
 188  *
 189  * Returns:     A pointer to the field.
 190  *
 191  * Use:         Creates a field structure for a prime field of size %$p$%,
 192  *              using efficient reduction for nice primes.
 193  */
 194
 195 extern field *field_niceprime(mp */*p*/);
 196
 197 /* --- @field_binpoly@ --- *
 198  *
 199  * Arguments:   @mp *p@ = an irreducible polynomial over %$\gf{2}$%
 200  *
 201  * Returns:     A pointer to the field.
 202  *
 203  * Use:         Creates a field structure for a binary field using naive
 204  *              arithmetic.
 205  */
 206
 207 extern field *field_binpoly(mp */*p*/);
 208
 209 /*----- That's all, folks -------------------------------------------------*/
 210
 211 #ifdef __cplusplus
 212   }
 213 #endif
 214
 215 #endif