2016-05-17 18:51:04 +00:00
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/*
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2018-09-11 12:22:14 +00:00
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* Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
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1998-12-21 10:52:47 +00:00
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*
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2016-05-17 18:51:04 +00:00
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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1998-12-21 10:52:47 +00:00
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*/
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2015-05-14 14:56:48 +00:00
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#include "internal/cryptlib.h"
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1998-12-21 10:52:47 +00:00
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#include "bn_lcl.h"
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/* r must not be a */
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2015-01-22 03:40:55 +00:00
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/*
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* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96
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*/
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2000-11-06 21:15:54 +00:00
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int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
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2018-08-10 17:31:22 +00:00
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{
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int ret = bn_sqr_fixed_top(r, a, ctx);
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bn_correct_top(r);
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bn_check_top(r);
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return ret;
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}
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int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
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2015-01-22 03:40:55 +00:00
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{
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int max, al;
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int ret = 0;
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BIGNUM *tmp, *rr;
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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bn_check_top(a);
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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al = a->top;
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if (al <= 0) {
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r->top = 0;
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r->neg = 0;
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return 1;
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}
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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BN_CTX_start(ctx);
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rr = (a != r) ? r : BN_CTX_get(ctx);
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tmp = BN_CTX_get(ctx);
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2017-06-22 10:52:29 +00:00
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if (rr == NULL || tmp == NULL)
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2015-01-22 03:40:55 +00:00
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goto err;
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2000-02-05 14:17:32 +00:00
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2015-01-22 03:40:55 +00:00
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max = 2 * al; /* Non-zero (from above) */
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if (bn_wexpand(rr, max) == NULL)
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goto err;
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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if (al == 4) {
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1998-12-21 11:00:56 +00:00
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#ifndef BN_SQR_COMBA
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2015-01-22 03:40:55 +00:00
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BN_ULONG t[8];
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bn_sqr_normal(rr->d, a->d, 4, t);
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1998-12-21 11:00:56 +00:00
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#else
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2015-01-22 03:40:55 +00:00
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bn_sqr_comba4(rr->d, a->d);
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1998-12-21 11:00:56 +00:00
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#endif
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2015-01-22 03:40:55 +00:00
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} else if (al == 8) {
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1998-12-21 11:00:56 +00:00
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#ifndef BN_SQR_COMBA
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2015-01-22 03:40:55 +00:00
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BN_ULONG t[16];
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bn_sqr_normal(rr->d, a->d, 8, t);
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1998-12-21 11:00:56 +00:00
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#else
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2015-01-22 03:40:55 +00:00
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bn_sqr_comba8(rr->d, a->d);
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1998-12-21 11:00:56 +00:00
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#endif
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2015-01-22 03:40:55 +00:00
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} else {
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1998-12-21 11:00:56 +00:00
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#if defined(BN_RECURSION)
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2015-01-22 03:40:55 +00:00
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if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
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BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];
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bn_sqr_normal(rr->d, a->d, al, t);
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} else {
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int j, k;
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1999-01-28 10:40:38 +00:00
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2015-01-22 03:40:55 +00:00
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j = BN_num_bits_word((BN_ULONG)al);
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j = 1 << (j - 1);
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k = j + j;
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if (al == j) {
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if (bn_wexpand(tmp, k * 2) == NULL)
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goto err;
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bn_sqr_recursive(rr->d, a->d, al, tmp->d);
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} else {
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if (bn_wexpand(tmp, max) == NULL)
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goto err;
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bn_sqr_normal(rr->d, a->d, al, tmp->d);
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}
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}
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1998-12-21 11:00:56 +00:00
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#else
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2015-01-22 03:40:55 +00:00
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if (bn_wexpand(tmp, max) == NULL)
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goto err;
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bn_sqr_normal(rr->d, a->d, al, tmp->d);
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1998-12-21 11:00:56 +00:00
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#endif
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2015-01-22 03:40:55 +00:00
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}
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1998-12-21 11:00:56 +00:00
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2015-01-22 03:40:55 +00:00
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rr->neg = 0;
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2018-07-06 13:02:29 +00:00
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rr->top = max;
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2018-08-10 17:31:22 +00:00
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rr->flags |= BN_FLG_FIXED_TOP;
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2016-11-15 23:54:28 +00:00
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if (r != rr && BN_copy(r, rr) == NULL)
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goto err;
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2015-01-22 03:40:55 +00:00
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ret = 1;
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2000-02-05 14:17:32 +00:00
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err:
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2015-01-22 03:40:55 +00:00
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bn_check_top(rr);
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bn_check_top(tmp);
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BN_CTX_end(ctx);
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2017-10-17 14:04:09 +00:00
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return ret;
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2015-01-22 03:40:55 +00:00
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}
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1998-12-21 11:00:56 +00:00
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/* tmp must have 2*n words */
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2000-11-16 21:35:41 +00:00
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void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
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2015-01-22 03:40:55 +00:00
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{
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int i, j, max;
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const BN_ULONG *ap;
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BN_ULONG *rp;
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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max = n * 2;
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ap = a;
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rp = r;
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rp[0] = rp[max - 1] = 0;
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rp++;
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j = n;
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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if (--j > 0) {
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ap++;
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rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
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rp += 2;
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}
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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for (i = n - 2; i > 0; i--) {
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j--;
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ap++;
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rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
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rp += 2;
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}
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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bn_add_words(r, r, r, max);
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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/* There will not be a carry */
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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bn_sqr_words(tmp, a, n);
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1998-12-21 10:52:47 +00:00
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2015-01-22 03:40:55 +00:00
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bn_add_words(r, r, tmp, max);
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}
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1998-12-21 10:52:47 +00:00
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1998-12-21 11:00:56 +00:00
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#ifdef BN_RECURSION
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2014-12-28 02:48:40 +00:00
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/*-
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* r is 2*n words in size,
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2000-09-19 23:25:00 +00:00
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* a and b are both n words in size. (There's not actually a 'b' here ...)
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1998-12-21 11:00:56 +00:00
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* n must be a power of 2.
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* We multiply and return the result.
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* t must be 2*n words in size
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2000-02-03 23:23:24 +00:00
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* We calculate
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1998-12-21 11:00:56 +00:00
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* a[0]*b[0]
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* a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
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* a[1]*b[1]
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*/
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2000-11-16 21:35:41 +00:00
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void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
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2015-01-22 03:40:55 +00:00
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{
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int n = n2 / 2;
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int zero, c1;
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BN_ULONG ln, lo, *p;
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1998-12-21 11:00:56 +00:00
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2015-01-22 03:40:55 +00:00
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if (n2 == 4) {
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# ifndef BN_SQR_COMBA
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bn_sqr_normal(r, a, 4, t);
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# else
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bn_sqr_comba4(r, a);
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# endif
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return;
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} else if (n2 == 8) {
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# ifndef BN_SQR_COMBA
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bn_sqr_normal(r, a, 8, t);
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# else
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bn_sqr_comba8(r, a);
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# endif
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return;
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}
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if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
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bn_sqr_normal(r, a, n2, t);
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return;
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}
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/* r=(a[0]-a[1])*(a[1]-a[0]) */
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c1 = bn_cmp_words(a, &(a[n]), n);
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zero = 0;
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if (c1 > 0)
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bn_sub_words(t, a, &(a[n]), n);
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else if (c1 < 0)
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bn_sub_words(t, &(a[n]), a, n);
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else
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zero = 1;
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1998-12-21 11:00:56 +00:00
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2015-01-22 03:40:55 +00:00
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/* The result will always be negative unless it is zero */
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p = &(t[n2 * 2]);
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1998-12-21 11:00:56 +00:00
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2015-01-22 03:40:55 +00:00
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if (!zero)
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bn_sqr_recursive(&(t[n2]), t, n, p);
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else
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2015-05-04 22:00:15 +00:00
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memset(&t[n2], 0, sizeof(*t) * n2);
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2015-01-22 03:40:55 +00:00
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bn_sqr_recursive(r, a, n, p);
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bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
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1998-12-21 11:00:56 +00:00
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2015-01-05 11:30:03 +00:00
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/*-
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* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
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* r[10] holds (a[0]*b[0])
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* r[32] holds (b[1]*b[1])
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*/
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1998-12-21 11:00:56 +00:00
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2015-01-22 03:40:55 +00:00
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c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
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1998-12-21 11:00:56 +00:00
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2015-01-22 03:40:55 +00:00
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/* t[32] is negative */
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c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
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1998-12-21 11:00:56 +00:00
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2015-01-05 11:30:03 +00:00
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/*-
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* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
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* r[10] holds (a[0]*a[0])
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* r[32] holds (a[1]*a[1])
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* c1 holds the carry bits
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*/
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2015-01-22 03:40:55 +00:00
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c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
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if (c1) {
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p = &(r[n + n2]);
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lo = *p;
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ln = (lo + c1) & BN_MASK2;
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*p = ln;
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1998-12-21 11:00:56 +00:00
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2015-01-22 03:40:55 +00:00
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/*
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* The overflow will stop before we over write words we should not
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* overwrite
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*/
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if (ln < (BN_ULONG)c1) {
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do {
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p++;
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lo = *p;
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ln = (lo + 1) & BN_MASK2;
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*p = ln;
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} while (ln == 0);
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}
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}
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}
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1998-12-21 11:00:56 +00:00
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#endif
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