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   1 /* -*-c-*-
   2  *
   3  * $Id: field.h,v 1.3.4.1 2004/03/20 00:13:31 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 1.3.4.1  2004/03/20 00:13:31  mdw
  34  * Projective coordinates for prime curves
  35  *
  36  * Revision 1.3  2002/01/13 13:48:44  mdw
  37  * Further progress.
  38  *
  39  * Revision 1.2  2001/05/07 17:30:13  mdw
  40  * Add an internal-representation no-op function.
  41  *
  42  * Revision 1.1  2001/04/29 18:12:33  mdw
  43  * Prototype version.
  44  *
  45  */
  46
  47 #ifndef CATACOMB_FIELD_H
  48 #define CATACOMB_FIELD_H
  49
  50 #ifdef __cplusplus
  51   extern "C" {
  52 #endif
  53
  54 /*----- Header files ------------------------------------------------------*/
  55
  56 #ifndef CATACOMB_MP_H
  57 #  include "mp.h"
  58 #endif
  59
  60 /*----- Data structures ---------------------------------------------------*/
  61
  62 typedef struct field {
  63   const struct field_ops *ops;          /* Field operations */
  64   mp *zero, *one;                       /* Identities in the field */
  65 } field;
  66
  67 typedef struct field_ops {
  68
  69   /* --- Universal operations --- */
  70
  71   void (*destroy)(field */*f*/);
  72
  73   mp *(*in)(field */*f*/, mp */*d*/, mp */*x*/);
  74   mp *(*out)(field */*f*/, mp */*d*/, mp */*x*/);
  75
  76   int (*zerop)(field */*f*/, mp */*x*/);
  77   mp *(*neg)(field */*f*/, mp */*d*/, mp */*x*/);
  78   mp *(*add)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
  79   mp *(*sub)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
  80   mp *(*mul)(field */*f*/, mp */*d*/, mp */*x*/, mp */*y*/);
  81   mp *(*sqr)(field */*f*/, mp */*d*/, mp */*x*/);
  82   mp *(*inv)(field */*f*/, mp */*d*/, mp */*x*/);
  83   mp *(*reduce)(field */*f*/, mp */*d*/, mp */*x*/);
  84
  85   /* --- Operations for prime fields only --- */
  86
  87   mp *(*dbl)(field */*f*/, mp */*d*/, mp */*x*/);
  88   mp *(*tpl)(field */*f*/, mp */*d*/, mp */*x*/);
  89   mp *(*qdl)(field */*f*/, mp */*d*/, mp */*x*/);
  90   mp *(*hlv)(field */*f*/, mp */*d*/, mp */*x*/);
  91   mp *(*sqrt)(field */*f*/, mp */*d*/, mp */*x*/);
  92
  93 } field_ops;
  94
  95 #define F_DESTROY(f)            (f)->ops->destroy((f))
  96
  97 #define F_IN(f, d, x)           (f)->ops->in((f), (d), (x))
  98 #define F_OUT(f, d, x)          (f)->ops->out((f), (d), (x))
  99
 100 #define F_ZEROP(f, x)           (f)->ops->zerop((f), (x))
 101 #define F_NEG(f, d, x)          (f)->ops->neg((f), (d), (x))
 102 #define F_ADD(f, d, x, y)       (f)->ops->add((f), (d), (x), (y))
 103 #define F_SUB(f, d, x, y)       (f)->ops->sub((f), (d), (x), (y))
 104 #define F_MUL(f, d, x, y)       (f)->ops->mul((f), (d), (x), (y))
 105 #define F_SQR(f, d, x)          (f)->ops->sqr((f), (d), (x))
 106 #define F_INV(f, d, x)          (f)->ops->inv((f), (d), (x))
 107 #define F_REDUCE(f, d, x)       (f)->ops->reduce((f), (d), (x))
 108
 109 #define F_DBL(f, d, x)          (f)->ops->dbl((f), (d), (x))
 110 #define F_TPL(f, d, x)          (f)->ops->tpl((f), (d), (x))
 111 #define F_QDL(f, d, x)          (f)->ops->qdl((f), (d), (x))
 112 #define F_HLV(f, d, x)          (f)->ops->hlv((f), (d), (x))
 113 #define F_SQRT(f, d, x)         (f)->ops->sqrt((f), (d), (x))
 114
 115 /*----- Helpful field operations ------------------------------------------*/
 116
 117 /* --- @field_id@ --- *
 118  *
 119  * Arguments:   @field *f@ = pointer to a field
 120  *              @mp *d@ = a destination element
 121  *              @mp *x@ = a source element
 122  *
 123  * Returns:     The result element.
 124  *
 125  * Use:         An identity operation which can be used if your field has no
 126  *              internal representation.
 127  */
 128
 129 extern mp *field_id(field */*f*/, mp */*d*/, mp */*x*/);
 130
 131 /*----- Creating fields ---------------------------------------------------*/
 132
 133 /* --- @field_prime@ --- *
 134  *
 135  * Arguments:   @mp *p@ = the characteristic of the field
 136  *
 137  * Returns:     A pointer to the field.
 138  *
 139  * Use:         Creates a field structure for a prime field of size %$p$%,
 140  *              using Montgomery reduction for arithmetic.
 141  */
 142
 143 extern field *field_prime(mp */*p*/);
 144
 145 /* --- @field_binpoly@ --- *
 146  *
 147  * Arguments:   @mp *p@ = an irreducible polynomial over %$\gf{2}$%
 148  *
 149  * Returns:     A pointer to the field.
 150  *
 151  * Use:         Creates a field structure for a binary field using naive
 152  *              arithmetic.
 153  */
 154
 155 extern field *field_binpoly(mp */*p*/);
 156
 157 /* --- @field_binsparsepoly@ --- *
 158  *
 159  * Arguments:   @unsigned deg@ = the degree of the field polynomial
 160  *              @const unsigned *c@ = degrees of nonzero coefficients
 161  *
 162  * Returns:     A pointer to the field.
 163  *
 164  * Use:         Creates a field structure for a binary field taking advantage
 165  *              of the sparseness of the given polynomial to improve
 166  *              reduction performance.
 167  */
 168
 169 extern field *field_binsparsepoly(unsigned /*deg*/, const unsigned */*c*/);
 170
 171 /*----- That's all, folks -------------------------------------------------*/
 172
 173 #ifdef __cplusplus
 174   }
 175 #endif
 176
 177 #endif