155714Skris/* crypto/bn/bn_sqr.c */ 255714Skris/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 355714Skris * All rights reserved. 455714Skris * 555714Skris * This package is an SSL implementation written 655714Skris * by Eric Young (eay@cryptsoft.com). 755714Skris * The implementation was written so as to conform with Netscapes SSL. 8280297Sjkim * 955714Skris * This library is free for commercial and non-commercial use as long as 1055714Skris * the following conditions are aheared to. The following conditions 1155714Skris * apply to all code found in this distribution, be it the RC4, RSA, 1255714Skris * lhash, DES, etc., code; not just the SSL code. The SSL documentation 1355714Skris * included with this distribution is covered by the same copyright terms 1455714Skris * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15280297Sjkim * 1655714Skris * Copyright remains Eric Young's, and as such any Copyright notices in 1755714Skris * the code are not to be removed. 1855714Skris * If this package is used in a product, Eric Young should be given attribution 1955714Skris * as the author of the parts of the library used. 2055714Skris * This can be in the form of a textual message at program startup or 2155714Skris * in documentation (online or textual) provided with the package. 22280297Sjkim * 2355714Skris * Redistribution and use in source and binary forms, with or without 2455714Skris * modification, are permitted provided that the following conditions 2555714Skris * are met: 2655714Skris * 1. Redistributions of source code must retain the copyright 2755714Skris * notice, this list of conditions and the following disclaimer. 2855714Skris * 2. Redistributions in binary form must reproduce the above copyright 2955714Skris * notice, this list of conditions and the following disclaimer in the 3055714Skris * documentation and/or other materials provided with the distribution. 3155714Skris * 3. All advertising materials mentioning features or use of this software 3255714Skris * must display the following acknowledgement: 3355714Skris * "This product includes cryptographic software written by 3455714Skris * Eric Young (eay@cryptsoft.com)" 3555714Skris * The word 'cryptographic' can be left out if the rouines from the library 3655714Skris * being used are not cryptographic related :-). 37280297Sjkim * 4. If you include any Windows specific code (or a derivative thereof) from 3855714Skris * the apps directory (application code) you must include an acknowledgement: 3955714Skris * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40280297Sjkim * 4155714Skris * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 4255714Skris * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 4355714Skris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 4455714Skris * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 4555714Skris * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 4655714Skris * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 4755714Skris * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 4855714Skris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 4955714Skris * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 5055714Skris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 5155714Skris * SUCH DAMAGE. 52280297Sjkim * 5355714Skris * The licence and distribution terms for any publically available version or 5455714Skris * derivative of this code cannot be changed. i.e. this code cannot simply be 5555714Skris * copied and put under another distribution licence 5655714Skris * [including the GNU Public Licence.] 5755714Skris */ 5855714Skris 5955714Skris#include <stdio.h> 6055714Skris#include "cryptlib.h" 6155714Skris#include "bn_lcl.h" 6255714Skris 6355714Skris/* r must not be a */ 64280297Sjkim/* 65280297Sjkim * I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 66280297Sjkim */ 67109998Smarkmint BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx) 68280297Sjkim{ 69340704Sjkim int ret = bn_sqr_fixed_top(r, a, ctx); 70340704Sjkim 71340704Sjkim bn_correct_top(r); 72340704Sjkim bn_check_top(r); 73340704Sjkim 74340704Sjkim return ret; 75340704Sjkim} 76340704Sjkim 77340704Sjkimint bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx) 78340704Sjkim{ 79280297Sjkim int max, al; 80280297Sjkim int ret = 0; 81280297Sjkim BIGNUM *tmp, *rr; 8255714Skris 8355714Skris#ifdef BN_COUNT 84280297Sjkim fprintf(stderr, "BN_sqr %d * %d\n", a->top, a->top); 8555714Skris#endif 86280297Sjkim bn_check_top(a); 8755714Skris 88280297Sjkim al = a->top; 89280297Sjkim if (al <= 0) { 90280297Sjkim r->top = 0; 91280297Sjkim r->neg = 0; 92280297Sjkim return 1; 93280297Sjkim } 9455714Skris 95280297Sjkim BN_CTX_start(ctx); 96280297Sjkim rr = (a != r) ? r : BN_CTX_get(ctx); 97280297Sjkim tmp = BN_CTX_get(ctx); 98280297Sjkim if (!rr || !tmp) 99280297Sjkim goto err; 10059191Skris 101280297Sjkim max = 2 * al; /* Non-zero (from above) */ 102280297Sjkim if (bn_wexpand(rr, max) == NULL) 103280297Sjkim goto err; 10455714Skris 105280297Sjkim if (al == 4) { 10655714Skris#ifndef BN_SQR_COMBA 107280297Sjkim BN_ULONG t[8]; 108280297Sjkim bn_sqr_normal(rr->d, a->d, 4, t); 10955714Skris#else 110280297Sjkim bn_sqr_comba4(rr->d, a->d); 11155714Skris#endif 112280297Sjkim } else if (al == 8) { 11355714Skris#ifndef BN_SQR_COMBA 114280297Sjkim BN_ULONG t[16]; 115280297Sjkim bn_sqr_normal(rr->d, a->d, 8, t); 11655714Skris#else 117280297Sjkim bn_sqr_comba8(rr->d, a->d); 11855714Skris#endif 119280297Sjkim } else { 12055714Skris#if defined(BN_RECURSION) 121280297Sjkim if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) { 122280297Sjkim BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2]; 123280297Sjkim bn_sqr_normal(rr->d, a->d, al, t); 124280297Sjkim } else { 125280297Sjkim int j, k; 12655714Skris 127280297Sjkim j = BN_num_bits_word((BN_ULONG)al); 128280297Sjkim j = 1 << (j - 1); 129280297Sjkim k = j + j; 130280297Sjkim if (al == j) { 131280297Sjkim if (bn_wexpand(tmp, k * 2) == NULL) 132280297Sjkim goto err; 133280297Sjkim bn_sqr_recursive(rr->d, a->d, al, tmp->d); 134280297Sjkim } else { 135280297Sjkim if (bn_wexpand(tmp, max) == NULL) 136280297Sjkim goto err; 137280297Sjkim bn_sqr_normal(rr->d, a->d, al, tmp->d); 138280297Sjkim } 139280297Sjkim } 14055714Skris#else 141280297Sjkim if (bn_wexpand(tmp, max) == NULL) 142280297Sjkim goto err; 143280297Sjkim bn_sqr_normal(rr->d, a->d, al, tmp->d); 14455714Skris#endif 145280297Sjkim } 14655714Skris 147280297Sjkim rr->neg = 0; 148337982Sjkim rr->top = max; 149340704Sjkim rr->flags |= BN_FLG_FIXED_TOP; 150312826Sjkim if (r != rr && BN_copy(r, rr) == NULL) 151312826Sjkim goto err; 152312826Sjkim 153280297Sjkim ret = 1; 15459191Skris err: 155280297Sjkim bn_check_top(rr); 156280297Sjkim bn_check_top(tmp); 157280297Sjkim BN_CTX_end(ctx); 158280297Sjkim return (ret); 159280297Sjkim} 16055714Skris 16155714Skris/* tmp must have 2*n words */ 162109998Smarkmvoid bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp) 163280297Sjkim{ 164280297Sjkim int i, j, max; 165280297Sjkim const BN_ULONG *ap; 166280297Sjkim BN_ULONG *rp; 16755714Skris 168280297Sjkim max = n * 2; 169280297Sjkim ap = a; 170280297Sjkim rp = r; 171280297Sjkim rp[0] = rp[max - 1] = 0; 172280297Sjkim rp++; 173280297Sjkim j = n; 17455714Skris 175280297Sjkim if (--j > 0) { 176280297Sjkim ap++; 177280297Sjkim rp[j] = bn_mul_words(rp, ap, j, ap[-1]); 178280297Sjkim rp += 2; 179280297Sjkim } 18055714Skris 181280297Sjkim for (i = n - 2; i > 0; i--) { 182280297Sjkim j--; 183280297Sjkim ap++; 184280297Sjkim rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]); 185280297Sjkim rp += 2; 186280297Sjkim } 18755714Skris 188280297Sjkim bn_add_words(r, r, r, max); 18955714Skris 190280297Sjkim /* There will not be a carry */ 19155714Skris 192280297Sjkim bn_sqr_words(tmp, a, n); 19355714Skris 194280297Sjkim bn_add_words(r, r, tmp, max); 195280297Sjkim} 19655714Skris 19755714Skris#ifdef BN_RECURSION 198280297Sjkim/*- 199280297Sjkim * r is 2*n words in size, 20068651Skris * a and b are both n words in size. (There's not actually a 'b' here ...) 20155714Skris * n must be a power of 2. 20255714Skris * We multiply and return the result. 20355714Skris * t must be 2*n words in size 20459191Skris * We calculate 20555714Skris * a[0]*b[0] 20655714Skris * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0]) 20755714Skris * a[1]*b[1] 20855714Skris */ 209109998Smarkmvoid bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t) 210280297Sjkim{ 211280297Sjkim int n = n2 / 2; 212280297Sjkim int zero, c1; 213280297Sjkim BN_ULONG ln, lo, *p; 21455714Skris 215280297Sjkim# ifdef BN_COUNT 216280297Sjkim fprintf(stderr, " bn_sqr_recursive %d * %d\n", n2, n2); 217280297Sjkim# endif 218280297Sjkim if (n2 == 4) { 219280297Sjkim# ifndef BN_SQR_COMBA 220280297Sjkim bn_sqr_normal(r, a, 4, t); 221280297Sjkim# else 222280297Sjkim bn_sqr_comba4(r, a); 223280297Sjkim# endif 224280297Sjkim return; 225280297Sjkim } else if (n2 == 8) { 226280297Sjkim# ifndef BN_SQR_COMBA 227280297Sjkim bn_sqr_normal(r, a, 8, t); 228280297Sjkim# else 229280297Sjkim bn_sqr_comba8(r, a); 230280297Sjkim# endif 231280297Sjkim return; 232280297Sjkim } 233280297Sjkim if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) { 234280297Sjkim bn_sqr_normal(r, a, n2, t); 235280297Sjkim return; 236280297Sjkim } 237280297Sjkim /* r=(a[0]-a[1])*(a[1]-a[0]) */ 238280297Sjkim c1 = bn_cmp_words(a, &(a[n]), n); 239280297Sjkim zero = 0; 240280297Sjkim if (c1 > 0) 241280297Sjkim bn_sub_words(t, a, &(a[n]), n); 242280297Sjkim else if (c1 < 0) 243280297Sjkim bn_sub_words(t, &(a[n]), a, n); 244280297Sjkim else 245280297Sjkim zero = 1; 24655714Skris 247280297Sjkim /* The result will always be negative unless it is zero */ 248280297Sjkim p = &(t[n2 * 2]); 24955714Skris 250280297Sjkim if (!zero) 251280297Sjkim bn_sqr_recursive(&(t[n2]), t, n, p); 252280297Sjkim else 253280297Sjkim memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG)); 254280297Sjkim bn_sqr_recursive(r, a, n, p); 255280297Sjkim bn_sqr_recursive(&(r[n2]), &(a[n]), n, p); 25655714Skris 257280297Sjkim /*- 258280297Sjkim * t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero 259280297Sjkim * r[10] holds (a[0]*b[0]) 260280297Sjkim * r[32] holds (b[1]*b[1]) 261280297Sjkim */ 26255714Skris 263280297Sjkim c1 = (int)(bn_add_words(t, r, &(r[n2]), n2)); 26455714Skris 265280297Sjkim /* t[32] is negative */ 266280297Sjkim c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2)); 26755714Skris 268280297Sjkim /*- 269280297Sjkim * t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1]) 270280297Sjkim * r[10] holds (a[0]*a[0]) 271280297Sjkim * r[32] holds (a[1]*a[1]) 272280297Sjkim * c1 holds the carry bits 273280297Sjkim */ 274280297Sjkim c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2)); 275280297Sjkim if (c1) { 276280297Sjkim p = &(r[n + n2]); 277280297Sjkim lo = *p; 278280297Sjkim ln = (lo + c1) & BN_MASK2; 279280297Sjkim *p = ln; 28055714Skris 281280297Sjkim /* 282280297Sjkim * The overflow will stop before we over write words we should not 283280297Sjkim * overwrite 284280297Sjkim */ 285280297Sjkim if (ln < (BN_ULONG)c1) { 286280297Sjkim do { 287280297Sjkim p++; 288280297Sjkim lo = *p; 289280297Sjkim ln = (lo + 1) & BN_MASK2; 290280297Sjkim *p = ln; 291280297Sjkim } while (ln == 0); 292280297Sjkim } 293280297Sjkim } 294280297Sjkim} 29555714Skris#endif 296