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227 lines
6.6 KiB
227 lines
6.6 KiB
/* crypto/bn/bn_word.c */ |
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
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* All rights reserved. |
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* |
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* This package is an SSL implementation written |
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* by Eric Young (eay@cryptsoft.com). |
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* The implementation was written so as to conform with Netscapes SSL. |
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* |
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* This library is free for commercial and non-commercial use as long as |
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* the following conditions are aheared to. The following conditions |
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* apply to all code found in this distribution, be it the RC4, RSA, |
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation |
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* included with this distribution is covered by the same copyright terms |
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* except that the holder is Tim Hudson (tjh@cryptsoft.com). |
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* |
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* Copyright remains Eric Young's, and as such any Copyright notices in |
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* the code are not to be removed. |
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* If this package is used in a product, Eric Young should be given attribution |
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* as the author of the parts of the library used. |
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* This can be in the form of a textual message at program startup or |
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* in documentation (online or textual) provided with the package. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. All advertising materials mentioning features or use of this software |
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* must display the following acknowledgement: |
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* "This product includes cryptographic software written by |
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* Eric Young (eay@cryptsoft.com)" |
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* The word 'cryptographic' can be left out if the rouines from the library |
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* being used are not cryptographic related :-). |
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* 4. If you include any Windows specific code (or a derivative thereof) from |
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* the apps directory (application code) you must include an acknowledgement: |
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" |
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* |
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* |
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* The licence and distribution terms for any publically available version or |
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* derivative of this code cannot be changed. i.e. this code cannot simply be |
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* copied and put under another distribution licence |
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* [including the GNU Public Licence.] |
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*/ |
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#include <stdio.h> |
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#include "cryptlib.h" |
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#include "bn_lcl.h" |
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BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w) |
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{ |
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#ifndef BN_LLONG |
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BN_ULONG ret = 0; |
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#else |
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BN_ULLONG ret = 0; |
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#endif |
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int i; |
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if (w == 0) |
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return (BN_ULONG)-1; |
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bn_check_top(a); |
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w &= BN_MASK2; |
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for (i = a->top - 1; i >= 0; i--) { |
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#ifndef BN_LLONG |
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ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w; |
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ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w; |
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#else |
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ret = (BN_ULLONG) (((ret << (BN_ULLONG) BN_BITS2) | a->d[i]) % |
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(BN_ULLONG) w); |
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#endif |
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} |
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return ((BN_ULONG)ret); |
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} |
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BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w) |
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{ |
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BN_ULONG ret = 0; |
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int i, j; |
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bn_check_top(a); |
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w &= BN_MASK2; |
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if (!w) |
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/* actually this an error (division by zero) */ |
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return (BN_ULONG)-1; |
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if (a->top == 0) |
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return 0; |
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/* normalize input (so bn_div_words doesn't complain) */ |
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j = BN_BITS2 - BN_num_bits_word(w); |
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w <<= j; |
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if (!BN_lshift(a, a, j)) |
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return (BN_ULONG)-1; |
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for (i = a->top - 1; i >= 0; i--) { |
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BN_ULONG l, d; |
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l = a->d[i]; |
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d = bn_div_words(ret, l, w); |
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ret = (l - ((d * w) & BN_MASK2)) & BN_MASK2; |
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a->d[i] = d; |
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} |
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if ((a->top > 0) && (a->d[a->top - 1] == 0)) |
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a->top--; |
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ret >>= j; |
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bn_check_top(a); |
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return (ret); |
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} |
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int BN_add_word(BIGNUM *a, BN_ULONG w) |
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{ |
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BN_ULONG l; |
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int i; |
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bn_check_top(a); |
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w &= BN_MASK2; |
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/* degenerate case: w is zero */ |
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if (!w) |
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return 1; |
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/* degenerate case: a is zero */ |
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if (BN_is_zero(a)) |
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return BN_set_word(a, w); |
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/* handle 'a' when negative */ |
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if (a->neg) { |
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a->neg = 0; |
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i = BN_sub_word(a, w); |
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if (!BN_is_zero(a)) |
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a->neg = !(a->neg); |
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return (i); |
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} |
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for (i = 0; w != 0 && i < a->top; i++) { |
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a->d[i] = l = (a->d[i] + w) & BN_MASK2; |
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w = (w > l) ? 1 : 0; |
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} |
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if (w && i == a->top) { |
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if (bn_wexpand(a, a->top + 1) == NULL) |
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return 0; |
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a->top++; |
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a->d[i] = w; |
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} |
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bn_check_top(a); |
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return (1); |
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} |
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int BN_sub_word(BIGNUM *a, BN_ULONG w) |
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{ |
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int i; |
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bn_check_top(a); |
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w &= BN_MASK2; |
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/* degenerate case: w is zero */ |
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if (!w) |
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return 1; |
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/* degenerate case: a is zero */ |
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if (BN_is_zero(a)) { |
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i = BN_set_word(a, w); |
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if (i != 0) |
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BN_set_negative(a, 1); |
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return i; |
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} |
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/* handle 'a' when negative */ |
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if (a->neg) { |
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a->neg = 0; |
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i = BN_add_word(a, w); |
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a->neg = 1; |
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return (i); |
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} |
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if ((a->top == 1) && (a->d[0] < w)) { |
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a->d[0] = w - a->d[0]; |
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a->neg = 1; |
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return (1); |
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} |
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i = 0; |
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for (;;) { |
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if (a->d[i] >= w) { |
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a->d[i] -= w; |
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break; |
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} else { |
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a->d[i] = (a->d[i] - w) & BN_MASK2; |
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i++; |
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w = 1; |
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} |
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} |
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if ((a->d[i] == 0) && (i == (a->top - 1))) |
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a->top--; |
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bn_check_top(a); |
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return (1); |
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} |
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int BN_mul_word(BIGNUM *a, BN_ULONG w) |
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{ |
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BN_ULONG ll; |
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bn_check_top(a); |
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w &= BN_MASK2; |
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if (a->top) { |
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if (w == 0) |
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BN_zero(a); |
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else { |
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ll = bn_mul_words(a->d, a->d, a->top, w); |
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if (ll) { |
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if (bn_wexpand(a, a->top + 1) == NULL) |
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return (0); |
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a->d[a->top++] = ll; |
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} |
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} |
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} |
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bn_check_top(a); |
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return (1); |
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}
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