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

   1 /* -*-c-*-
   2  *
   3  * $Id: gfreduce.h,v 1.1.2.1 2004/03/21 22:39:46 mdw Exp $
   4  *
   5  * Reduction modulo sparse binary polynomials
   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: gfreduce.h,v $
  33  * Revision 1.1.2.1  2004/03/21 22:39:46  mdw
  34  * Elliptic curves on binary fields work.
  35  *
  36  */
  37
  38 #ifndef CATACOMB_GFREDUCE_H
  39 #define CATACOMB_GFREDUCE_H
  40
  41 #ifdef __cplusplus
  42   extern "C" {
  43 #endif
  44
  45 /*----- Header files ------------------------------------------------------*/
  46
  47 #ifndef CATACOMB_GF_H
  48 #  include "gf.h"
  49 #endif
  50
  51 /*----- Data structures ---------------------------------------------------*/
  52
  53 typedef struct gfreduce_instr {
  54   unsigned op;                          /* Instruction opcode */
  55   size_t arg;                           /* Immediate argument */
  56 } gfreduce_instr;
  57
  58 enum {
  59   GFRI_LOAD,                            /* Load @p[arg]@ */
  60   GFRI_LSL,                             /* XOR with @w << arg@ */
  61   GFRI_LSR,                             /* XOR with @w >> arg@ */
  62   GFRI_STORE,                           /* Store @p[arg]@ */
  63   GFRI_MAX
  64 };
  65
  66 typedef struct gfreduce {
  67   size_t lim;                           /* Word of degree bit */
  68   mpw mask;                             /* Mask for degree word */
  69   mp *p;                                /* Copy of the polynomial */
  70   size_t in;                            /* Number of instruction words */
  71   gfreduce_instr *iv, *liv;             /* Vector of instructions */
  72 } gfreduce;
  73
  74 /*----- Functions provided ------------------------------------------------*/
  75
  76 /* --- @gfreduce_create@ --- *
  77  *
  78  * Arguments:   @gfreduce *r@ = structure to fill in
  79  *              @mp *x@ = a (hopefully sparse) polynomial
  80  *
  81  * Returns:     ---
  82  *
  83  * Use:         Initializes a context structure for reduction.
  84  */
  85
  86 extern void gfreduce_create(gfreduce */*r*/, mp */*p*/);
  87
  88 /* --- @gfreduce_destroy@ --- *
  89  *
  90  * Arguments:   @gfreduce *r@ = structure to free
  91  *
  92  * Returns:     ---
  93  *
  94  * Use:         Reclaims the resources from a reduction context.
  95  */
  96
  97 extern void gfreduce_destroy(gfreduce */*r*/);
  98
  99 /* --- @gfreduce_dump@ --- *
 100  *
 101  * Arguments:   @gfreduce *r@ = structure to dump
 102  *              @FILE *fp@ = file to dump on
 103  *
 104  * Returns:     ---
 105  *
 106  * Use:         Dumps a reduction context.
 107  */
 108
 109 extern void gfreduce_dump(gfreduce */*r*/, FILE */*fp*/);
 110
 111 /* --- @gfreduce_do@ --- *
 112  *
 113  * Arguments:   @gfreduce *r@ = reduction context
 114  *              @mp *d@ = destination
 115  *              @mp *x@ = source
 116  *
 117  * Returns:     Destination, @x@ reduced modulo the reduction poly.
 118  */
 119
 120 extern mp *gfreduce_do(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 121
 122 /* --- @gfreduce_sqrt@ --- *
 123  *
 124  * Arguments:   @gfreduce *r@ = pointer to reduction context
 125  *              @mp *d@ = destination
 126  *              @mp *x@ = some polynomial
 127  *
 128  * Returns:     The square root of @x@ modulo @r->p@, or null.
 129  */
 130
 131 extern mp *gfreduce_sqrt(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 132
 133 /* --- @gfreduce_trace@ --- *
 134  *
 135  * Arguments:   @gfreduce *r@ = pointer to reduction context
 136  *              @mp *x@ = some polynomial
 137  *
 138  * Returns:     The trace of @x@. (%$\Tr(x)=x + x^2 + \cdots + x^{2^{m-1}}$%
 139  *              if %$x \in \gf{2^m}$%).
 140  */
 141
 142 extern int gfreduce_trace(gfreduce */*r*/, mp */*x*/);
 143
 144 /* --- @gfreduce_halftrace@ --- *
 145  *
 146  * Arguments:   @gfreduce *r@ = pointer to reduction context
 147  *              @mp *d@ = destination
 148  *              @mp *x@ = some polynomial
 149  *
 150  * Returns:     The half-trace of @x@.
 151  *              (%$\HfTr(x)= x + x^{2^2} + \cdots + x^{2^{m-1}}$%
 152  *              if %$x \in \gf{2^m}$% with %$m$% odd).
 153  */
 154
 155 extern mp *gfreduce_halftrace(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 156
 157 /* --- @gfreduce_quadsolve@ --- *
 158  *
 159  * Arguments:   @gfreduce *r@ = pointer to reduction context
 160  *              @mp *d@ = destination
 161  *              @mp *x@ = some polynomial
 162  *
 163  * Returns:     A polynomial @y@ such that %$y^2 + y = x$%, or null.
 164  */
 165
 166 extern mp *gfreduce_quadsolve(gfreduce */*r*/, mp */*d*/, mp */*x*/);
 167
 168 /* --- @gfreduce_exp@ --- *
 169  *
 170  * Arguments:   @gfreduce *gr@ = pointer to reduction context
 171  *              @mp *d@ = fake destination
 172  *              @mp *a@ = base
 173  *              @mp *e@ = exponent
 174  *
 175  * Returns:     Result, %$a^e \bmod m$%.
 176  */
 177
 178 extern mp *gfreduce_exp(gfreduce */*gr*/, mp */*d*/, mp */*a*/, mp */*e*/);
 179
 180 /*----- That's all, folks -------------------------------------------------*/
 181
 182 #ifdef __cplusplus
 183   }
 184 #endif
 185
 186 #endif