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

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