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

   1 /* -*-c-*-
   2  *
   3  * $Id: field.h,v 1.8 2004/03/27 17:54:11 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 1.8  2004/03/27 17:54:11  mdw
  34  * Standard curves and curve checking.
  35  *
  36  * Revision 1.7  2004/03/27 00:04:46  mdw
  37  * Implement efficient reduction for pleasant-looking primes.
  38  *
  39  * Revision 1.6  2004/03/23 15:19:32  mdw
  40  * Test elliptic curves more thoroughly.
  41  *
  42  * Revision 1.5  2004/03/23 12:08:26  mdw
  43  * Random field-element selection.
  44  *
  45  * Revision 1.4  2004/03/21 22:52:06  mdw
  46  * Merge and close elliptic curve branch.
  47  *
  48  * Revision 1.3.4.2  2004/03/21 22:39:46  mdw
  49  * Elliptic curves on binary fields work.
  50  *
  51  * Revision 1.3.4.1  2004/03/20 00:13:31  mdw
  52  * Projective coordinates for prime curves
  53  *
  54  * Revision 1.3  2002/01/13 13:48:44  mdw
  55  * Further progress.
  56  *
  57  * Revision 1.2  2001/05/07 17:30:13  mdw
  58  * Add an internal-representation no-op function.
  59  *
  60  * Revision 1.1  2001/04/29 18:12:33  mdw
  61  * Prototype version.
  62  *
  63  */
  64
  65 #ifndef CATACOMB_FIELD_H
  66 #define CATACOMB_FIELD_H
  67
  68 #ifdef __cplusplus
  69   extern "C" {
  70 #endif
  71
  72 /*----- Header files ------------------------------------------------------*/
  73
  74 #ifndef CATACOMB_GRAND_H
  75 #  include "grand.h"
  76 #endif
  77
  78 #ifndef CATACOMB_MP_H
  79 #  include "mp.h"
  80 #endif
  81
  82 #ifndef CATACOMB_QDPARSE_H
  83 #  include "qdparse.h"
  84 #endif
  85
  86 /*----- Data structures ---------------------------------------------------*/
  87
  88 typedef struct field {
  89   const struct field_ops *ops;          /* Field operations */
  90   mp *zero, *one;                       /* Identities in the field */
  91   mp *m;                                /* Modulus (prime and binary) */
  92   unsigned long nbits;                  /* Length of field element in bits */
  93   size_t noctets;                       /* Length of element in octets */
  94 } field;
  95
  96 enum {
  97   FTY_PRIME,
  98   FTY_BINARY
  99 };
 100
 101 typedef struct field_ops {
 102
 103   /* --- General information --- */
 104
 105   unsigned ty;                          /* What kind of field this is */
 106   const char *name;                     /* Human-readable name string */
 107
 108   /* --- Universal operations --- */
 109
 110   void (*destroy)(field */*f*/);
 111   mp *(*rand)(field */*f*/, mp */*d*/, grand */*r*/);
 112
 113   mp *(*in)(field */*f*/, mp */*d*/, mp */*x*/);
 114   mp *(*out)(field */*f*/, mp */*d*/, mp */*x*/);
 115
 116   int (*zerop)(field */*f*/, mp */*x*/);
 117   mp *(*neg)(field */*f*/, mp */*d*/, mp */*x*/);
 118   mp *(*add)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
 119   mp *(*sub)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
 120   mp *(*mul)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
 121   mp *(*sqr)(field */*f*/, mp */*d*/, mp */*x*/);
 122   mp *(*inv)(field */*f*/, mp */*d*/, mp */*x*/);
 123   mp *(*reduce)(field */*f*/, mp */*d*/, mp */*x*/);
 124   mp *(*sqrt)(field */*f*/, mp */*d*/, mp */*x*/);
 125
 126   /* --- Operations for binary fields only --- */
 127
 128   mp *(*quadsolve)(field */*f*/, mp */*d*/, mp */*x*/);
 129
 130   /* --- Operations for prime fields only --- */
 131
 132   mp *(*dbl)(field */*f*/, mp */*d*/, mp */*x*/);
 133   mp *(*tpl)(field */*f*/, mp */*d*/, mp */*x*/);
 134   mp *(*qdl)(field */*f*/, mp */*d*/, mp */*x*/);
 135   mp *(*hlv)(field */*f*/, mp */*d*/, mp */*x*/);
 136
 137 } field_ops;
 138
 139 #define F_TYPE(f)               (f)->ops->ty
 140 #define F_NAME(f)               (f)->ops->name
 141
 142 #define F_DESTROY(f)            (f)->ops->destroy((f))
 143 #define F_RAND(f, d, r)         (f)->ops->rand((f), (d), (r))
 144
 145 #define F_IN(f, d, x)           (f)->ops->in((f), (d), (x))
 146 #define F_OUT(f, d, x)          (f)->ops->out((f), (d), (x))
 147
 148 #define F_ZEROP(f, x)           (f)->ops->zerop((f), (x))
 149 #define F_NEG(f, d, x)          (f)->ops->neg((f), (d), (x))
 150 #define F_ADD(f, d, x, y)       (f)->ops->add((f), (d), (x), (y))
 151 #define F_SUB(f, d, x, y)       (f)->ops->sub((f), (d), (x), (y))
 152 #define F_MUL(f, d, x, y)       (f)->ops->mul((f), (d), (x), (y))
 153 #define F_SQR(f, d, x)          (f)->ops->sqr((f), (d), (x))
 154 #define F_INV(f, d, x)          (f)->ops->inv((f), (d), (x))
 155 #define F_REDUCE(f, d, x)       (f)->ops->reduce((f), (d), (x))
 156 #define F_SQRT(f, d, x)         (f)->ops->sqrt((f), (d), (x))
 157
 158 #define F_QUADSOLVE(f, d, x)    (f)->ops->quadsolve((f), (d), (x))
 159
 160 #define F_DBL(f, d, x)          (f)->ops->dbl((f), (d), (x))
 161 #define F_TPL(f, d, x)          (f)->ops->tpl((f), (d), (x))
 162 #define F_QDL(f, d, x)          (f)->ops->qdl((f), (d), (x))
 163 #define F_HLV(f, d, x)          (f)->ops->hlv((f), (d), (x))
 164
 165 /*----- Helpful field operations ------------------------------------------*/
 166
 167 /* --- @field_id@ --- *
 168  *
 169  * Arguments:   @field *f@ = pointer to a field
 170  *              @mp *d@ = a destination element
 171  *              @mp *x@ = a source element
 172  *
 173  * Returns:     The result element.
 174  *
 175  * Use:         An identity operation which can be used if your field has no
 176  *              internal representation.
 177  */
 178
 179 extern mp *field_id(field */*f*/, mp */*d*/, mp */*x*/);
 180
 181 /*----- Creating fields ---------------------------------------------------*/
 182
 183 /* --- @field_prime@ --- *
 184  *
 185  * Arguments:   @mp *p@ = the characteristic of the field
 186  *
 187  * Returns:     A pointer to the field.
 188  *
 189  * Use:         Creates a field structure for a prime field of size %$p$%,
 190  *              using Montgomery reduction for arithmetic.
 191  */
 192
 193 extern field *field_prime(mp */*p*/);
 194
 195 /* --- @field_niceprime@ --- *
 196  *
 197  * Arguments:   @mp *p@ = the characteristic of the field
 198  *
 199  * Returns:     A pointer to the field.
 200  *
 201  * Use:         Creates a field structure for a prime field of size %$p$%,
 202  *              using efficient reduction for nice primes.
 203  */
 204
 205 extern field *field_niceprime(mp */*p*/);
 206
 207 /* --- @field_binpoly@ --- *
 208  *
 209  * Arguments:   @mp *p@ = an irreducible polynomial over %$\gf{2}$%
 210  *
 211  * Returns:     A pointer to the field.
 212  *
 213  * Use:         Creates a field structure for a binary field using naive
 214  *              arithmetic.
 215  */
 216
 217 extern field *field_binpoly(mp */*p*/);
 218
 219 /* --- @field_parse@ --- *
 220  *
 221  * Arguments:   @qd_parse *qd@ = parser context
 222  *
 223  * Returns:     Field pointer if OK, or null.
 224  *
 225  * Use:         Parses a field description, which has the form
 226  *
 227  *                * `prime', `niceprime' or `binpoly'
 228  *                * an optional `:'
 229  *                * the field modulus
 230  */
 231
 232 extern field *field_parse(qd_parse */*qd*/);
 233
 234 /*----- That's all, folks -------------------------------------------------*/
 235
 236 #ifdef __cplusplus
 237   }
 238 #endif
 239
 240 #endif