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. 8296341Sdelphij * 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). 15296341Sdelphij * 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. 22296341Sdelphij * 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 :-). 37296341Sdelphij * 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)" 40296341Sdelphij * 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. 52296341Sdelphij * 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 */ 64296341Sdelphij/* 65296341Sdelphij * I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 66296341Sdelphij */ 67109998Smarkmint BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx) 68296341Sdelphij{ 69296341Sdelphij int max, al; 70296341Sdelphij int ret = 0; 71296341Sdelphij BIGNUM *tmp, *rr; 7255714Skris 7355714Skris#ifdef BN_COUNT 74296341Sdelphij fprintf(stderr, "BN_sqr %d * %d\n", a->top, a->top); 7555714Skris#endif 76296341Sdelphij bn_check_top(a); 7755714Skris 78296341Sdelphij al = a->top; 79296341Sdelphij if (al <= 0) { 80296341Sdelphij r->top = 0; 81296341Sdelphij r->neg = 0; 82296341Sdelphij return 1; 83296341Sdelphij } 8455714Skris 85296341Sdelphij BN_CTX_start(ctx); 86296341Sdelphij rr = (a != r) ? r : BN_CTX_get(ctx); 87296341Sdelphij tmp = BN_CTX_get(ctx); 88296341Sdelphij if (!rr || !tmp) 89296341Sdelphij goto err; 9059191Skris 91296341Sdelphij max = 2 * al; /* Non-zero (from above) */ 92296341Sdelphij if (bn_wexpand(rr, max) == NULL) 93296341Sdelphij goto err; 9455714Skris 95296341Sdelphij if (al == 4) { 9655714Skris#ifndef BN_SQR_COMBA 97296341Sdelphij BN_ULONG t[8]; 98296341Sdelphij bn_sqr_normal(rr->d, a->d, 4, t); 9955714Skris#else 100296341Sdelphij bn_sqr_comba4(rr->d, a->d); 10155714Skris#endif 102296341Sdelphij } else if (al == 8) { 10355714Skris#ifndef BN_SQR_COMBA 104296341Sdelphij BN_ULONG t[16]; 105296341Sdelphij bn_sqr_normal(rr->d, a->d, 8, t); 10655714Skris#else 107296341Sdelphij bn_sqr_comba8(rr->d, a->d); 10855714Skris#endif 109296341Sdelphij } else { 11055714Skris#if defined(BN_RECURSION) 111296341Sdelphij if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) { 112296341Sdelphij BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2]; 113296341Sdelphij bn_sqr_normal(rr->d, a->d, al, t); 114296341Sdelphij } else { 115296341Sdelphij int j, k; 11655714Skris 117296341Sdelphij j = BN_num_bits_word((BN_ULONG)al); 118296341Sdelphij j = 1 << (j - 1); 119296341Sdelphij k = j + j; 120296341Sdelphij if (al == j) { 121296341Sdelphij if (bn_wexpand(tmp, k * 2) == NULL) 122296341Sdelphij goto err; 123296341Sdelphij bn_sqr_recursive(rr->d, a->d, al, tmp->d); 124296341Sdelphij } else { 125296341Sdelphij if (bn_wexpand(tmp, max) == NULL) 126296341Sdelphij goto err; 127296341Sdelphij bn_sqr_normal(rr->d, a->d, al, tmp->d); 128296341Sdelphij } 129296341Sdelphij } 13055714Skris#else 131296341Sdelphij if (bn_wexpand(tmp, max) == NULL) 132296341Sdelphij goto err; 133296341Sdelphij bn_sqr_normal(rr->d, a->d, al, tmp->d); 13455714Skris#endif 135296341Sdelphij } 13655714Skris 137296341Sdelphij rr->neg = 0; 138296341Sdelphij /* 139296341Sdelphij * If the most-significant half of the top word of 'a' is zero, then the 140296341Sdelphij * square of 'a' will max-1 words. 141296341Sdelphij */ 142296341Sdelphij if (a->d[al - 1] == (a->d[al - 1] & BN_MASK2l)) 143296341Sdelphij rr->top = max - 1; 144296341Sdelphij else 145296341Sdelphij rr->top = max; 146296341Sdelphij if (rr != r) 147296341Sdelphij BN_copy(r, rr); 148296341Sdelphij ret = 1; 14959191Skris err: 150296341Sdelphij bn_check_top(rr); 151296341Sdelphij bn_check_top(tmp); 152296341Sdelphij BN_CTX_end(ctx); 153296341Sdelphij return (ret); 154296341Sdelphij} 15555714Skris 15655714Skris/* tmp must have 2*n words */ 157109998Smarkmvoid bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp) 158296341Sdelphij{ 159296341Sdelphij int i, j, max; 160296341Sdelphij const BN_ULONG *ap; 161296341Sdelphij BN_ULONG *rp; 16255714Skris 163296341Sdelphij max = n * 2; 164296341Sdelphij ap = a; 165296341Sdelphij rp = r; 166296341Sdelphij rp[0] = rp[max - 1] = 0; 167296341Sdelphij rp++; 168296341Sdelphij j = n; 16955714Skris 170296341Sdelphij if (--j > 0) { 171296341Sdelphij ap++; 172296341Sdelphij rp[j] = bn_mul_words(rp, ap, j, ap[-1]); 173296341Sdelphij rp += 2; 174296341Sdelphij } 17555714Skris 176296341Sdelphij for (i = n - 2; i > 0; i--) { 177296341Sdelphij j--; 178296341Sdelphij ap++; 179296341Sdelphij rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]); 180296341Sdelphij rp += 2; 181296341Sdelphij } 18255714Skris 183296341Sdelphij bn_add_words(r, r, r, max); 18455714Skris 185296341Sdelphij /* There will not be a carry */ 18655714Skris 187296341Sdelphij bn_sqr_words(tmp, a, n); 18855714Skris 189296341Sdelphij bn_add_words(r, r, tmp, max); 190296341Sdelphij} 19155714Skris 19255714Skris#ifdef BN_RECURSION 193296341Sdelphij/*- 194296341Sdelphij * r is 2*n words in size, 19568651Skris * a and b are both n words in size. (There's not actually a 'b' here ...) 19655714Skris * n must be a power of 2. 19755714Skris * We multiply and return the result. 19855714Skris * t must be 2*n words in size 19959191Skris * We calculate 20055714Skris * a[0]*b[0] 20155714Skris * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0]) 20255714Skris * a[1]*b[1] 20355714Skris */ 204109998Smarkmvoid bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t) 205296341Sdelphij{ 206296341Sdelphij int n = n2 / 2; 207296341Sdelphij int zero, c1; 208296341Sdelphij BN_ULONG ln, lo, *p; 20955714Skris 210296341Sdelphij# ifdef BN_COUNT 211296341Sdelphij fprintf(stderr, " bn_sqr_recursive %d * %d\n", n2, n2); 212296341Sdelphij# endif 213296341Sdelphij if (n2 == 4) { 214296341Sdelphij# ifndef BN_SQR_COMBA 215296341Sdelphij bn_sqr_normal(r, a, 4, t); 216296341Sdelphij# else 217296341Sdelphij bn_sqr_comba4(r, a); 218296341Sdelphij# endif 219296341Sdelphij return; 220296341Sdelphij } else if (n2 == 8) { 221296341Sdelphij# ifndef BN_SQR_COMBA 222296341Sdelphij bn_sqr_normal(r, a, 8, t); 223296341Sdelphij# else 224296341Sdelphij bn_sqr_comba8(r, a); 225296341Sdelphij# endif 226296341Sdelphij return; 227296341Sdelphij } 228296341Sdelphij if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) { 229296341Sdelphij bn_sqr_normal(r, a, n2, t); 230296341Sdelphij return; 231296341Sdelphij } 232296341Sdelphij /* r=(a[0]-a[1])*(a[1]-a[0]) */ 233296341Sdelphij c1 = bn_cmp_words(a, &(a[n]), n); 234296341Sdelphij zero = 0; 235296341Sdelphij if (c1 > 0) 236296341Sdelphij bn_sub_words(t, a, &(a[n]), n); 237296341Sdelphij else if (c1 < 0) 238296341Sdelphij bn_sub_words(t, &(a[n]), a, n); 239296341Sdelphij else 240296341Sdelphij zero = 1; 24155714Skris 242296341Sdelphij /* The result will always be negative unless it is zero */ 243296341Sdelphij p = &(t[n2 * 2]); 24455714Skris 245296341Sdelphij if (!zero) 246296341Sdelphij bn_sqr_recursive(&(t[n2]), t, n, p); 247296341Sdelphij else 248296341Sdelphij memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG)); 249296341Sdelphij bn_sqr_recursive(r, a, n, p); 250296341Sdelphij bn_sqr_recursive(&(r[n2]), &(a[n]), n, p); 25155714Skris 252296341Sdelphij /*- 253296341Sdelphij * t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero 254296341Sdelphij * r[10] holds (a[0]*b[0]) 255296341Sdelphij * r[32] holds (b[1]*b[1]) 256296341Sdelphij */ 25755714Skris 258296341Sdelphij c1 = (int)(bn_add_words(t, r, &(r[n2]), n2)); 25955714Skris 260296341Sdelphij /* t[32] is negative */ 261296341Sdelphij c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2)); 26255714Skris 263296341Sdelphij /*- 264296341Sdelphij * t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1]) 265296341Sdelphij * r[10] holds (a[0]*a[0]) 266296341Sdelphij * r[32] holds (a[1]*a[1]) 267296341Sdelphij * c1 holds the carry bits 268296341Sdelphij */ 269296341Sdelphij c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2)); 270296341Sdelphij if (c1) { 271296341Sdelphij p = &(r[n + n2]); 272296341Sdelphij lo = *p; 273296341Sdelphij ln = (lo + c1) & BN_MASK2; 274296341Sdelphij *p = ln; 27555714Skris 276296341Sdelphij /* 277296341Sdelphij * The overflow will stop before we over write words we should not 278296341Sdelphij * overwrite 279296341Sdelphij */ 280296341Sdelphij if (ln < (BN_ULONG)c1) { 281296341Sdelphij do { 282296341Sdelphij p++; 283296341Sdelphij lo = *p; 284296341Sdelphij ln = (lo + 1) & BN_MASK2; 285296341Sdelphij *p = ln; 286296341Sdelphij } while (ln == 0); 287296341Sdelphij } 288296341Sdelphij } 289296341Sdelphij} 29055714Skris#endif 291