DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Mercurial (fddffdeab170)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "ecp_fp.h"
#include <stdlib.h>

#define ECFP_BSIZE 224
#define ECFP_NUMDOUBLES 10

#include "ecp_fpinc.c"

/* Performs a single step of reduction, just on the uppermost float
 * (assumes already tidied), and then retidies. Note, this does not
 * guarantee that the result will be less than p. */
void
ecfp224_singleReduce(double *r, const EC_group_fp * group)
{
	double q;

	ECFP_ASSERT(group->doubleBitSize == 24);
	ECFP_ASSERT(group->primeBitSize == 224);
	ECFP_ASSERT(group->numDoubles == 10);

	q = r[ECFP_NUMDOUBLES - 1] - ecfp_beta_224;
	q += group->bitSize_alpha;
	q -= group->bitSize_alpha;

	r[ECFP_NUMDOUBLES - 1] -= q;
	r[0] -= q * ecfp_twom224;
	r[4] += q * ecfp_twom128;

	ecfp_positiveTidy(r, group);
}

/* 
 * Performs imperfect reduction.  This might leave some negative terms,
 * and one more reduction might be required for the result to be between 0 
 * and p-1. x should be be an array of at least 20, and r at least 10 x
 * and r can be the same, but then the upper parts of r are not zeroed */
void
ecfp224_reduce(double *r, double *x, const EC_group_fp * group)
{

	double x10, x11, x12, x13, x14, q;

	ECFP_ASSERT(group->doubleBitSize == 24);
	ECFP_ASSERT(group->primeBitSize == 224);
	ECFP_ASSERT(group->numDoubles == 10);

	/* Tidy just the upper bits of x.  Don't need to tidy the lower ones
	 * yet. */
	ecfp_tidyUpper(x, group);

	x10 = x[10] + x[16] * ecfp_twom128;
	x11 = x[11] + x[17] * ecfp_twom128;
	x12 = x[12] + x[18] * ecfp_twom128;
	x13 = x[13] + x[19] * ecfp_twom128;

	/* Tidy up, or we won't have enough bits later to add it in */
	q = x10 + group->alpha[11];
	q -= group->alpha[11];
	x10 -= q;
	x11 = x11 + q;

	q = x11 + group->alpha[12];
	q -= group->alpha[12];
	x11 -= q;
	x12 = x12 + q;

	q = x12 + group->alpha[13];
	q -= group->alpha[13];
	x12 -= q;
	x13 = x13 + q;

	q = x13 + group->alpha[14];
	q -= group->alpha[14];
	x13 -= q;
	x14 = x[14] + q;

	r[9] = x[9] + x[15] * ecfp_twom128 - x[19] * ecfp_twom224;
	r[8] = x[8] + x14 * ecfp_twom128 - x[18] * ecfp_twom224;
	r[7] = x[7] + x13 * ecfp_twom128 - x[17] * ecfp_twom224;
	r[6] = x[6] + x12 * ecfp_twom128 - x[16] * ecfp_twom224;
	r[5] = x[5] + x11 * ecfp_twom128 - x[15] * ecfp_twom224;
	r[4] = x[4] + x10 * ecfp_twom128 - x14 * ecfp_twom224;
	r[3] = x[3] - x13 * ecfp_twom224;
	r[2] = x[2] - x12 * ecfp_twom224;
	r[1] = x[1] - x11 * ecfp_twom224;
	r[0] = x[0] - x10 * ecfp_twom224;

	/* 
	 * Tidy up just r[ECFP_NUMDOUBLES-2] so that the number of reductions
	 * is accurate plus or minus one.  (Rather than tidy all to make it
	 * totally accurate) */
	q = r[ECFP_NUMDOUBLES - 2] + group->alpha[ECFP_NUMDOUBLES - 1];
	q -= group->alpha[ECFP_NUMDOUBLES - 1];
	r[ECFP_NUMDOUBLES - 2] -= q;
	r[ECFP_NUMDOUBLES - 1] += q;

	/* Tidy up the excess bits on r[ECFP_NUMDOUBLES-1] using reduction */
	/* Use ecfp_beta so we get a positive res */
	q = r[ECFP_NUMDOUBLES - 1] - ecfp_beta_224;
	q += group->bitSize_alpha;
	q -= group->bitSize_alpha;

	r[ECFP_NUMDOUBLES - 1] -= q;
	r[0] -= q * ecfp_twom224;
	r[4] += q * ecfp_twom128;

	ecfp_tidyShort(r, group);
}

/* Sets group to use optimized calculations in this file */
mp_err
ec_group_set_nistp224_fp(ECGroup *group)
{

	EC_group_fp *fpg;

	/* Allocate memory for floating point group data */
	fpg = (EC_group_fp *) malloc(sizeof(EC_group_fp));
	if (fpg == NULL) {
		return MP_MEM;
	}

	fpg->numDoubles = ECFP_NUMDOUBLES;
	fpg->primeBitSize = ECFP_BSIZE;
	fpg->orderBitSize = 224;
	fpg->doubleBitSize = 24;
	fpg->numInts = (ECFP_BSIZE + ECL_BITS - 1) / ECL_BITS;
	fpg->aIsM3 = 1;
	fpg->ecfp_singleReduce = &ecfp224_singleReduce;
	fpg->ecfp_reduce = &ecfp224_reduce;
	fpg->ecfp_tidy = &ecfp_tidy;

	fpg->pt_add_jac_aff = &ecfp224_pt_add_jac_aff;
	fpg->pt_add_jac = &ecfp224_pt_add_jac;
	fpg->pt_add_jm_chud = &ecfp224_pt_add_jm_chud;
	fpg->pt_add_chud = &ecfp224_pt_add_chud;
	fpg->pt_dbl_jac = &ecfp224_pt_dbl_jac;
	fpg->pt_dbl_jm = &ecfp224_pt_dbl_jm;
	fpg->pt_dbl_aff2chud = &ecfp224_pt_dbl_aff2chud;
	fpg->precompute_chud = &ecfp224_precompute_chud;
	fpg->precompute_jac = &ecfp224_precompute_jac;

	group->point_mul = &ec_GFp_point_mul_wNAF_fp;
	group->points_mul = &ec_pts_mul_basic;
	group->extra1 = fpg;
	group->extra_free = &ec_GFp_extra_free_fp;

	ec_set_fp_precision(fpg);
	fpg->bitSize_alpha = ECFP_TWO224 * fpg->alpha[0];

	return MP_OKAY;
}