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- /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
- *
- * This package is an SSL implementation written
- * by Eric Young (eay@cryptsoft.com).
- * The implementation was written so as to conform with Netscapes SSL.
- *
- * This library is free for commercial and non-commercial use as long as
- * the following conditions are aheared to. The following conditions
- * apply to all code found in this distribution, be it the RC4, RSA,
- * lhash, DES, etc., code; not just the SSL code. The SSL documentation
- * included with this distribution is covered by the same copyright terms
- * except that the holder is Tim Hudson (tjh@cryptsoft.com).
- *
- * Copyright remains Eric Young's, and as such any Copyright notices in
- * the code are not to be removed.
- * If this package is used in a product, Eric Young should be given attribution
- * as the author of the parts of the library used.
- * This can be in the form of a textual message at program startup or
- * in documentation (online or textual) provided with the package.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * "This product includes cryptographic software written by
- * Eric Young (eay@cryptsoft.com)"
- * The word 'cryptographic' can be left out if the rouines from the library
- * being used are not cryptographic related :-).
- * 4. If you include any Windows specific code (or a derivative thereof) from
- * the apps directory (application code) you must include an acknowledgement:
- * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
- *
- * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * The licence and distribution terms for any publically available version or
- * derivative of this code cannot be changed. i.e. this code cannot simply be
- * copied and put under another distribution licence
- * [including the GNU Public Licence.] */
-
- #include <openssl/bn.h>
-
- #include <assert.h>
-
- #include "internal.h"
-
-
- void bn_mul_normal(BN_ULONG *r, BN_ULONG *a, int na, BN_ULONG *b, int nb) {
- BN_ULONG *rr;
-
- if (na < nb) {
- int itmp;
- BN_ULONG *ltmp;
-
- itmp = na;
- na = nb;
- nb = itmp;
- ltmp = a;
- a = b;
- b = ltmp;
- }
- rr = &(r[na]);
- if (nb <= 0) {
- (void)bn_mul_words(r, a, na, 0);
- return;
- } else {
- rr[0] = bn_mul_words(r, a, na, b[0]);
- }
-
- for (;;) {
- if (--nb <= 0) {
- return;
- }
- rr[1] = bn_mul_add_words(&(r[1]), a, na, b[1]);
- if (--nb <= 0) {
- return;
- }
- rr[2] = bn_mul_add_words(&(r[2]), a, na, b[2]);
- if (--nb <= 0) {
- return;
- }
- rr[3] = bn_mul_add_words(&(r[3]), a, na, b[3]);
- if (--nb <= 0) {
- return;
- }
- rr[4] = bn_mul_add_words(&(r[4]), a, na, b[4]);
- rr += 4;
- r += 4;
- b += 4;
- }
- }
-
- void bn_mul_low_normal(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n) {
- bn_mul_words(r, a, n, b[0]);
-
- for (;;) {
- if (--n <= 0) {
- return;
- }
- bn_mul_add_words(&(r[1]), a, n, b[1]);
- if (--n <= 0) {
- return;
- }
- bn_mul_add_words(&(r[2]), a, n, b[2]);
- if (--n <= 0) {
- return;
- }
- bn_mul_add_words(&(r[3]), a, n, b[3]);
- if (--n <= 0) {
- return;
- }
- bn_mul_add_words(&(r[4]), a, n, b[4]);
- r += 4;
- b += 4;
- }
- }
-
- #if !defined(OPENSSL_X86)
- /* Here follows specialised variants of bn_add_words() and bn_sub_words(). They
- * have the property performing operations on arrays of different sizes. The
- * sizes of those arrays is expressed through cl, which is the common length (
- * basicall, min(len(a),len(b)) ), and dl, which is the delta between the two
- * lengths, calculated as len(a)-len(b). All lengths are the number of
- * BN_ULONGs... For the operations that require a result array as parameter,
- * it must have the length cl+abs(dl). These functions should probably end up
- * in bn_asm.c as soon as there are assembler counterparts for the systems that
- * use assembler files. */
-
- static BN_ULONG bn_sub_part_words(BN_ULONG *r, const BN_ULONG *a,
- const BN_ULONG *b, int cl, int dl) {
- BN_ULONG c, t;
-
- assert(cl >= 0);
- c = bn_sub_words(r, a, b, cl);
-
- if (dl == 0)
- return c;
-
- r += cl;
- a += cl;
- b += cl;
-
- if (dl < 0) {
- for (;;) {
- t = b[0];
- r[0] = (0 - t - c) & BN_MASK2;
- if (t != 0) {
- c = 1;
- }
- if (++dl >= 0) {
- break;
- }
-
- t = b[1];
- r[1] = (0 - t - c) & BN_MASK2;
- if (t != 0) {
- c = 1;
- }
- if (++dl >= 0) {
- break;
- }
-
- t = b[2];
- r[2] = (0 - t - c) & BN_MASK2;
- if (t != 0) {
- c = 1;
- }
- if (++dl >= 0) {
- break;
- }
-
- t = b[3];
- r[3] = (0 - t - c) & BN_MASK2;
- if (t != 0) {
- c = 1;
- }
- if (++dl >= 0) {
- break;
- }
-
- b += 4;
- r += 4;
- }
- } else {
- int save_dl = dl;
- while (c) {
- t = a[0];
- r[0] = (t - c) & BN_MASK2;
- if (t != 0) {
- c = 0;
- }
- if (--dl <= 0) {
- break;
- }
-
- t = a[1];
- r[1] = (t - c) & BN_MASK2;
- if (t != 0) {
- c = 0;
- }
- if (--dl <= 0) {
- break;
- }
-
- t = a[2];
- r[2] = (t - c) & BN_MASK2;
- if (t != 0) {
- c = 0;
- }
- if (--dl <= 0) {
- break;
- }
-
- t = a[3];
- r[3] = (t - c) & BN_MASK2;
- if (t != 0) {
- c = 0;
- }
- if (--dl <= 0) {
- break;
- }
-
- save_dl = dl;
- a += 4;
- r += 4;
- }
- if (dl > 0) {
- if (save_dl > dl) {
- switch (save_dl - dl) {
- case 1:
- r[1] = a[1];
- if (--dl <= 0) {
- break;
- }
- case 2:
- r[2] = a[2];
- if (--dl <= 0) {
- break;
- }
- case 3:
- r[3] = a[3];
- if (--dl <= 0) {
- break;
- }
- }
- a += 4;
- r += 4;
- }
- }
-
- if (dl > 0) {
- for (;;) {
- r[0] = a[0];
- if (--dl <= 0) {
- break;
- }
- r[1] = a[1];
- if (--dl <= 0) {
- break;
- }
- r[2] = a[2];
- if (--dl <= 0) {
- break;
- }
- r[3] = a[3];
- if (--dl <= 0) {
- break;
- }
-
- a += 4;
- r += 4;
- }
- }
- }
-
- return c;
- }
- #else
- /* On other platforms the function is defined in asm. */
- BN_ULONG bn_sub_part_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b,
- int cl, int dl);
- #endif
-
- /* Karatsuba recursive multiplication algorithm
- * (cf. Knuth, The Art of Computer Programming, Vol. 2) */
-
- /* r is 2*n2 words in size,
- * a and b are both n2 words in size.
- * n2 must be a power of 2.
- * We multiply and return the result.
- * t must be 2*n2 words in size
- * We calculate
- * a[0]*b[0]
- * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
- * a[1]*b[1]
- */
- /* dnX may not be positive, but n2/2+dnX has to be */
- static void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
- int dna, int dnb, BN_ULONG *t) {
- int n = n2 / 2, c1, c2;
- int tna = n + dna, tnb = n + dnb;
- unsigned int neg, zero;
- BN_ULONG ln, lo, *p;
-
- /* Only call bn_mul_comba 8 if n2 == 8 and the
- * two arrays are complete [steve]
- */
- if (n2 == 8 && dna == 0 && dnb == 0) {
- bn_mul_comba8(r, a, b);
- return;
- }
-
- /* Else do normal multiply */
- if (n2 < BN_MUL_RECURSIVE_SIZE_NORMAL) {
- bn_mul_normal(r, a, n2 + dna, b, n2 + dnb);
- if ((dna + dnb) < 0)
- memset(&r[2 * n2 + dna + dnb], 0, sizeof(BN_ULONG) * -(dna + dnb));
- return;
- }
-
- /* r=(a[0]-a[1])*(b[1]-b[0]) */
- c1 = bn_cmp_part_words(a, &(a[n]), tna, n - tna);
- c2 = bn_cmp_part_words(&(b[n]), b, tnb, tnb - n);
- zero = neg = 0;
- switch (c1 * 3 + c2) {
- case -4:
- bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
- bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
- break;
- case -3:
- zero = 1;
- break;
- case -2:
- bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
- bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n); /* + */
- neg = 1;
- break;
- case -1:
- case 0:
- case 1:
- zero = 1;
- break;
- case 2:
- bn_sub_part_words(t, a, &(a[n]), tna, n - tna); /* + */
- bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
- neg = 1;
- break;
- case 3:
- zero = 1;
- break;
- case 4:
- bn_sub_part_words(t, a, &(a[n]), tna, n - tna);
- bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n);
- break;
- }
-
- if (n == 4 && dna == 0 && dnb == 0) {
- /* XXX: bn_mul_comba4 could take extra args to do this well */
- if (!zero) {
- bn_mul_comba4(&(t[n2]), t, &(t[n]));
- } else {
- memset(&(t[n2]), 0, 8 * sizeof(BN_ULONG));
- }
-
- bn_mul_comba4(r, a, b);
- bn_mul_comba4(&(r[n2]), &(a[n]), &(b[n]));
- } else if (n == 8 && dna == 0 && dnb == 0) {
- /* XXX: bn_mul_comba8 could take extra args to do this well */
- if (!zero) {
- bn_mul_comba8(&(t[n2]), t, &(t[n]));
- } else {
- memset(&(t[n2]), 0, 16 * sizeof(BN_ULONG));
- }
-
- bn_mul_comba8(r, a, b);
- bn_mul_comba8(&(r[n2]), &(a[n]), &(b[n]));
- } else {
- p = &(t[n2 * 2]);
- if (!zero) {
- bn_mul_recursive(&(t[n2]), t, &(t[n]), n, 0, 0, p);
- } else {
- memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG));
- }
- bn_mul_recursive(r, a, b, n, 0, 0, p);
- bn_mul_recursive(&(r[n2]), &(a[n]), &(b[n]), n, dna, dnb, p);
- }
-
- /* t[32] holds (a[0]-a[1])*(b[1]-b[0]), c1 is the sign
- * r[10] holds (a[0]*b[0])
- * r[32] holds (b[1]*b[1]) */
-
- c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
-
- if (neg) {
- /* if t[32] is negative */
- c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
- } else {
- /* Might have a carry */
- c1 += (int)(bn_add_words(&(t[n2]), &(t[n2]), t, n2));
- }
-
- /* t[32] holds (a[0]-a[1])*(b[1]-b[0])+(a[0]*b[0])+(a[1]*b[1])
- * r[10] holds (a[0]*b[0])
- * r[32] holds (b[1]*b[1])
- * c1 holds the carry bits */
- c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
- if (c1) {
- p = &(r[n + n2]);
- lo = *p;
- ln = (lo + c1) & BN_MASK2;
- *p = ln;
-
- /* The overflow will stop before we over write
- * words we should not overwrite */
- if (ln < (BN_ULONG)c1) {
- do {
- p++;
- lo = *p;
- ln = (lo + 1) & BN_MASK2;
- *p = ln;
- } while (ln == 0);
- }
- }
- }
-
- /* n+tn is the word length
- * t needs to be n*4 is size, as does r */
- /* tnX may not be negative but less than n */
- static void bn_mul_part_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n,
- int tna, int tnb, BN_ULONG *t) {
- int i, j, n2 = n * 2;
- int c1, c2, neg;
- BN_ULONG ln, lo, *p;
-
- if (n < 8) {
- bn_mul_normal(r, a, n + tna, b, n + tnb);
- return;
- }
-
- /* r=(a[0]-a[1])*(b[1]-b[0]) */
- c1 = bn_cmp_part_words(a, &(a[n]), tna, n - tna);
- c2 = bn_cmp_part_words(&(b[n]), b, tnb, tnb - n);
- neg = 0;
- switch (c1 * 3 + c2) {
- case -4:
- bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
- bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
- break;
- case -3:
- /* break; */
- case -2:
- bn_sub_part_words(t, &(a[n]), a, tna, tna - n); /* - */
- bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n); /* + */
- neg = 1;
- break;
- case -1:
- case 0:
- case 1:
- /* break; */
- case 2:
- bn_sub_part_words(t, a, &(a[n]), tna, n - tna); /* + */
- bn_sub_part_words(&(t[n]), b, &(b[n]), tnb, n - tnb); /* - */
- neg = 1;
- break;
- case 3:
- /* break; */
- case 4:
- bn_sub_part_words(t, a, &(a[n]), tna, n - tna);
- bn_sub_part_words(&(t[n]), &(b[n]), b, tnb, tnb - n);
- break;
- }
-
- if (n == 8) {
- bn_mul_comba8(&(t[n2]), t, &(t[n]));
- bn_mul_comba8(r, a, b);
- bn_mul_normal(&(r[n2]), &(a[n]), tna, &(b[n]), tnb);
- memset(&(r[n2 + tna + tnb]), 0, sizeof(BN_ULONG) * (n2 - tna - tnb));
- } else {
- p = &(t[n2 * 2]);
- bn_mul_recursive(&(t[n2]), t, &(t[n]), n, 0, 0, p);
- bn_mul_recursive(r, a, b, n, 0, 0, p);
- i = n / 2;
- /* If there is only a bottom half to the number,
- * just do it */
- if (tna > tnb) {
- j = tna - i;
- } else {
- j = tnb - i;
- }
-
- if (j == 0) {
- bn_mul_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i, tnb - i, p);
- memset(&(r[n2 + i * 2]), 0, sizeof(BN_ULONG) * (n2 - i * 2));
- } else if (j > 0) {
- /* eg, n == 16, i == 8 and tn == 11 */
- bn_mul_part_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i, tnb - i, p);
- memset(&(r[n2 + tna + tnb]), 0, sizeof(BN_ULONG) * (n2 - tna - tnb));
- } else {
- /* (j < 0) eg, n == 16, i == 8 and tn == 5 */
- memset(&(r[n2]), 0, sizeof(BN_ULONG) * n2);
- if (tna < BN_MUL_RECURSIVE_SIZE_NORMAL &&
- tnb < BN_MUL_RECURSIVE_SIZE_NORMAL) {
- bn_mul_normal(&(r[n2]), &(a[n]), tna, &(b[n]), tnb);
- } else {
- for (;;) {
- i /= 2;
- /* these simplified conditions work
- * exclusively because difference
- * between tna and tnb is 1 or 0 */
- if (i < tna || i < tnb) {
- bn_mul_part_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i,
- tnb - i, p);
- break;
- } else if (i == tna || i == tnb) {
- bn_mul_recursive(&(r[n2]), &(a[n]), &(b[n]), i, tna - i, tnb - i,
- p);
- break;
- }
- }
- }
- }
- }
-
- /* t[32] holds (a[0]-a[1])*(b[1]-b[0]), c1 is the sign
- * r[10] holds (a[0]*b[0])
- * r[32] holds (b[1]*b[1])
- */
-
- c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
-
- if (neg) {
- /* if t[32] is negative */
- c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
- } else {
- /* Might have a carry */
- c1 += (int)(bn_add_words(&(t[n2]), &(t[n2]), t, n2));
- }
-
- /* t[32] holds (a[0]-a[1])*(b[1]-b[0])+(a[0]*b[0])+(a[1]*b[1])
- * r[10] holds (a[0]*b[0])
- * r[32] holds (b[1]*b[1])
- * c1 holds the carry bits */
- c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
- if (c1) {
- p = &(r[n + n2]);
- lo = *p;
- ln = (lo + c1) & BN_MASK2;
- *p = ln;
-
- /* The overflow will stop before we over write
- * words we should not overwrite */
- if (ln < (BN_ULONG)c1) {
- do {
- p++;
- lo = *p;
- ln = (lo + 1) & BN_MASK2;
- *p = ln;
- } while (ln == 0);
- }
- }
- }
-
- int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx) {
- int ret = 0;
- int top, al, bl;
- BIGNUM *rr;
- int i;
- BIGNUM *t = NULL;
- int j = 0, k;
-
- al = a->top;
- bl = b->top;
-
- if ((al == 0) || (bl == 0)) {
- BN_zero(r);
- return 1;
- }
- top = al + bl;
-
- BN_CTX_start(ctx);
- if ((r == a) || (r == b)) {
- if ((rr = BN_CTX_get(ctx)) == NULL) {
- goto err;
- }
- } else {
- rr = r;
- }
- rr->neg = a->neg ^ b->neg;
-
- i = al - bl;
- if (i == 0) {
- if (al == 8) {
- if (bn_wexpand(rr, 16) == NULL) {
- goto err;
- }
- rr->top = 16;
- bn_mul_comba8(rr->d, a->d, b->d);
- goto end;
- }
- }
-
- if ((al >= BN_MULL_SIZE_NORMAL) && (bl >= BN_MULL_SIZE_NORMAL)) {
- if (i >= -1 && i <= 1) {
- /* Find out the power of two lower or equal
- to the longest of the two numbers */
- if (i >= 0) {
- j = BN_num_bits_word((BN_ULONG)al);
- }
- if (i == -1) {
- j = BN_num_bits_word((BN_ULONG)bl);
- }
- j = 1 << (j - 1);
- assert(j <= al || j <= bl);
- k = j + j;
- t = BN_CTX_get(ctx);
- if (t == NULL) {
- goto err;
- }
- if (al > j || bl > j) {
- if (bn_wexpand(t, k * 4) == NULL) {
- goto err;
- }
- if (bn_wexpand(rr, k * 4) == NULL) {
- goto err;
- }
- bn_mul_part_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
- } else {
- /* al <= j || bl <= j */
- if (bn_wexpand(t, k * 2) == NULL) {
- goto err;
- }
- if (bn_wexpand(rr, k * 2) == NULL) {
- goto err;
- }
- bn_mul_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
- }
- rr->top = top;
- goto end;
- }
- }
-
- if (bn_wexpand(rr, top) == NULL) {
- goto err;
- }
- rr->top = top;
- bn_mul_normal(rr->d, a->d, al, b->d, bl);
-
- end:
- bn_correct_top(rr);
- if (r != rr) {
- BN_copy(r, rr);
- }
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- return ret;
- }
-
- /* tmp must have 2*n words */
- static void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp) {
- int i, j, max;
- const BN_ULONG *ap;
- BN_ULONG *rp;
-
- max = n * 2;
- ap = a;
- rp = r;
- rp[0] = rp[max - 1] = 0;
- rp++;
- j = n;
-
- if (--j > 0) {
- ap++;
- rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
- rp += 2;
- }
-
- for (i = n - 2; i > 0; i--) {
- j--;
- ap++;
- rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
- rp += 2;
- }
-
- bn_add_words(r, r, r, max);
-
- /* There will not be a carry */
-
- bn_sqr_words(tmp, a, n);
-
- bn_add_words(r, r, tmp, max);
- }
-
- /* r is 2*n words in size,
- * a and b are both n words in size. (There's not actually a 'b' here ...)
- * n must be a power of 2.
- * We multiply and return the result.
- * t must be 2*n words in size
- * We calculate
- * a[0]*b[0]
- * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
- * a[1]*b[1]
- */
- static void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t) {
- int n = n2 / 2;
- int zero, c1;
- BN_ULONG ln, lo, *p;
-
- if (n2 == 4) {
- bn_sqr_comba4(r, a);
- return;
- } else if (n2 == 8) {
- bn_sqr_comba8(r, a);
- return;
- }
- if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
- bn_sqr_normal(r, a, n2, t);
- return;
- }
- /* r=(a[0]-a[1])*(a[1]-a[0]) */
- c1 = bn_cmp_words(a, &(a[n]), n);
- zero = 0;
- if (c1 > 0) {
- bn_sub_words(t, a, &(a[n]), n);
- } else if (c1 < 0) {
- bn_sub_words(t, &(a[n]), a, n);
- } else {
- zero = 1;
- }
-
- /* The result will always be negative unless it is zero */
- p = &(t[n2 * 2]);
-
- if (!zero) {
- bn_sqr_recursive(&(t[n2]), t, n, p);
- } else {
- memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG));
- }
- bn_sqr_recursive(r, a, n, p);
- bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
-
- /* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
- * r[10] holds (a[0]*b[0])
- * r[32] holds (b[1]*b[1]) */
-
- c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
-
- /* t[32] is negative */
- c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
-
- /* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
- * r[10] holds (a[0]*a[0])
- * r[32] holds (a[1]*a[1])
- * c1 holds the carry bits */
- c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
- if (c1) {
- p = &(r[n + n2]);
- lo = *p;
- ln = (lo + c1) & BN_MASK2;
- *p = ln;
-
- /* The overflow will stop before we over write
- * words we should not overwrite */
- if (ln < (BN_ULONG)c1) {
- do {
- p++;
- lo = *p;
- ln = (lo + 1) & BN_MASK2;
- *p = ln;
- } while (ln == 0);
- }
- }
- }
-
- int BN_mul_word(BIGNUM *bn, BN_ULONG w) {
- BN_ULONG ll;
-
- w &= BN_MASK2;
- if (!bn->top) {
- return 1;
- }
-
- if (w == 0) {
- BN_zero(bn);
- return 1;
- }
-
- ll = bn_mul_words(bn->d, bn->d, bn->top, w);
- if (ll) {
- if (bn_wexpand(bn, bn->top + 1) == NULL) {
- return 0;
- }
- bn->d[bn->top++] = ll;
- }
-
- return 1;
- }
-
- int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx) {
- int max, al;
- int ret = 0;
- BIGNUM *tmp, *rr;
-
- al = a->top;
- if (al <= 0) {
- r->top = 0;
- return 1;
- }
-
- BN_CTX_start(ctx);
- rr = (a != r) ? r : BN_CTX_get(ctx);
- tmp = BN_CTX_get(ctx);
- if (!rr || !tmp) {
- goto err;
- }
-
- max = 2 * al; /* Non-zero (from above) */
- if (bn_wexpand(rr, max) == NULL) {
- goto err;
- }
-
- if (al == 4) {
- bn_sqr_comba4(rr->d, a->d);
- } else if (al == 8) {
- bn_sqr_comba8(rr->d, a->d);
- } else {
- if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
- BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];
- bn_sqr_normal(rr->d, a->d, al, t);
- } else {
- int j, k;
-
- j = BN_num_bits_word((BN_ULONG)al);
- j = 1 << (j - 1);
- k = j + j;
- if (al == j) {
- if (bn_wexpand(tmp, k * 2) == NULL) {
- goto err;
- }
- bn_sqr_recursive(rr->d, a->d, al, tmp->d);
- } else {
- if (bn_wexpand(tmp, max) == NULL) {
- goto err;
- }
- bn_sqr_normal(rr->d, a->d, al, tmp->d);
- }
- }
- }
-
- rr->neg = 0;
- /* If the most-significant half of the top word of 'a' is zero, then
- * the square of 'a' will max-1 words. */
- if (a->d[al - 1] == (a->d[al - 1] & BN_MASK2l)) {
- rr->top = max - 1;
- } else {
- rr->top = max;
- }
-
- if (rr != r) {
- BN_copy(r, rr);
- }
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- return ret;
- }
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