762 lines
17 KiB
C
762 lines
17 KiB
C
/* crypto/bn/bn_lib.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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#ifndef BN_DEBUG
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# undef NDEBUG /* avoid conflicting definitions */
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# define NDEBUG
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#endif
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#include <assert.h>
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#include <limits.h>
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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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const char *BN_version="Big Number" OPENSSL_VERSION_PTEXT;
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/* For a 32 bit machine
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* 2 - 4 == 128
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* 3 - 8 == 256
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* 4 - 16 == 512
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* 5 - 32 == 1024
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* 6 - 64 == 2048
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* 7 - 128 == 4096
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* 8 - 256 == 8192
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*/
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static int bn_limit_bits=0;
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static int bn_limit_num=8; /* (1<<bn_limit_bits) */
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static int bn_limit_bits_low=0;
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static int bn_limit_num_low=8; /* (1<<bn_limit_bits_low) */
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static int bn_limit_bits_high=0;
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static int bn_limit_num_high=8; /* (1<<bn_limit_bits_high) */
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static int bn_limit_bits_mont=0;
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static int bn_limit_num_mont=8; /* (1<<bn_limit_bits_mont) */
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void BN_set_params(int mult, int high, int low, int mont)
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{
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if (mult >= 0)
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{
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if (mult > (sizeof(int)*8)-1)
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mult=sizeof(int)*8-1;
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bn_limit_bits=mult;
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bn_limit_num=1<<mult;
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}
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if (high >= 0)
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{
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if (high > (sizeof(int)*8)-1)
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high=sizeof(int)*8-1;
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bn_limit_bits_high=high;
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bn_limit_num_high=1<<high;
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}
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if (low >= 0)
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{
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if (low > (sizeof(int)*8)-1)
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low=sizeof(int)*8-1;
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bn_limit_bits_low=low;
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bn_limit_num_low=1<<low;
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}
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if (mont >= 0)
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{
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if (mont > (sizeof(int)*8)-1)
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mont=sizeof(int)*8-1;
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bn_limit_bits_mont=mont;
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bn_limit_num_mont=1<<mont;
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}
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}
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int BN_get_params(int which)
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{
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if (which == 0) return(bn_limit_bits);
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else if (which == 1) return(bn_limit_bits_high);
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else if (which == 2) return(bn_limit_bits_low);
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else if (which == 3) return(bn_limit_bits_mont);
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else return(0);
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}
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BIGNUM *BN_value_one(void)
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{
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static BN_ULONG data_one=1L;
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static BIGNUM const_one={&data_one,1,1,0};
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return(&const_one);
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}
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char *BN_options(void)
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{
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static int init=0;
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static char data[16];
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if (!init)
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{
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init++;
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#ifdef BN_LLONG
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sprintf(data,"bn(%d,%d)",(int)sizeof(BN_ULLONG)*8,
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(int)sizeof(BN_ULONG)*8);
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#else
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sprintf(data,"bn(%d,%d)",(int)sizeof(BN_ULONG)*8,
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(int)sizeof(BN_ULONG)*8);
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#endif
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}
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return(data);
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}
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int BN_num_bits_word(BN_ULONG l)
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{
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static const char bits[256]={
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0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,
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5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
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6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
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6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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};
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#if defined(SIXTY_FOUR_BIT_LONG)
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if (l & 0xffffffff00000000L)
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{
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if (l & 0xffff000000000000L)
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{
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if (l & 0xff00000000000000L)
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{
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return(bits[(int)(l>>56)]+56);
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}
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else return(bits[(int)(l>>48)]+48);
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}
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else
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{
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if (l & 0x0000ff0000000000L)
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{
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return(bits[(int)(l>>40)]+40);
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}
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else return(bits[(int)(l>>32)]+32);
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}
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}
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else
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#else
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#ifdef SIXTY_FOUR_BIT
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if (l & 0xffffffff00000000LL)
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{
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if (l & 0xffff000000000000LL)
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{
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if (l & 0xff00000000000000LL)
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{
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return(bits[(int)(l>>56)]+56);
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}
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else return(bits[(int)(l>>48)]+48);
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}
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else
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{
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if (l & 0x0000ff0000000000LL)
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{
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return(bits[(int)(l>>40)]+40);
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}
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else return(bits[(int)(l>>32)]+32);
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}
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}
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else
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#endif
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#endif
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{
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#if defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
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if (l & 0xffff0000L)
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{
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if (l & 0xff000000L)
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return(bits[(int)(l>>24L)]+24);
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else return(bits[(int)(l>>16L)]+16);
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}
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else
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#endif
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{
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#if defined(SIXTEEN_BIT) || defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
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if (l & 0xff00L)
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return(bits[(int)(l>>8)]+8);
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else
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#endif
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return(bits[(int)(l )] );
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}
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}
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}
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int BN_num_bits(const BIGNUM *a)
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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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if (a->top == 0) return(0);
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l=a->d[a->top-1];
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assert(l != 0);
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i=(a->top-1)*BN_BITS2;
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return(i+BN_num_bits_word(l));
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}
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void BN_clear_free(BIGNUM *a)
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{
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int i;
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if (a == NULL) return;
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if (a->d != NULL)
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{
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memset(a->d,0,a->dmax*sizeof(a->d[0]));
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if (!(BN_get_flags(a,BN_FLG_STATIC_DATA)))
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OPENSSL_free(a->d);
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}
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i=BN_get_flags(a,BN_FLG_MALLOCED);
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memset(a,0,sizeof(BIGNUM));
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if (i)
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OPENSSL_free(a);
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}
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void BN_free(BIGNUM *a)
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{
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if (a == NULL) return;
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if ((a->d != NULL) && !(BN_get_flags(a,BN_FLG_STATIC_DATA)))
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OPENSSL_free(a->d);
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a->flags|=BN_FLG_FREE; /* REMOVE? */
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if (a->flags & BN_FLG_MALLOCED)
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OPENSSL_free(a);
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}
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void BN_init(BIGNUM *a)
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{
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memset(a,0,sizeof(BIGNUM));
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}
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BIGNUM *BN_new(void)
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{
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BIGNUM *ret;
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if ((ret=(BIGNUM *)OPENSSL_malloc(sizeof(BIGNUM))) == NULL)
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{
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BNerr(BN_F_BN_NEW,ERR_R_MALLOC_FAILURE);
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return(NULL);
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}
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ret->flags=BN_FLG_MALLOCED;
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ret->top=0;
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ret->neg=0;
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ret->dmax=0;
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ret->d=NULL;
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return(ret);
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}
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/* This is an internal function that should not be used in applications.
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* It ensures that 'b' has enough room for a 'words' word number number.
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* It is mostly used by the various BIGNUM routines. If there is an error,
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* NULL is returned. If not, 'b' is returned. */
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BIGNUM *bn_expand2(BIGNUM *b, int words)
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{
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BN_ULONG *A,*a;
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const BN_ULONG *B;
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int i;
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bn_check_top(b);
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if (words > b->dmax)
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{
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if (words > (INT_MAX/(4*BN_BITS2)))
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{
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BNerr(BN_F_BN_EXPAND2,BN_R_BIGNUM_TOO_LONG);
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return NULL;
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}
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bn_check_top(b);
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if (BN_get_flags(b,BN_FLG_STATIC_DATA))
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{
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BNerr(BN_F_BN_EXPAND2,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
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return(NULL);
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}
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a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*(words+1));
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if (A == NULL)
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{
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BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE);
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return(NULL);
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}
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#if 1
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B=b->d;
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/* Check if the previous number needs to be copied */
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if (B != NULL)
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{
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#if 0
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/* This lot is an unrolled loop to copy b->top
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* BN_ULONGs from B to A
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*/
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/*
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* I have nothing against unrolling but it's usually done for
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* several reasons, namely:
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* - minimize percentage of decision making code, i.e. branches;
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* - avoid cache trashing;
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* - make it possible to schedule loads earlier;
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* Now let's examine the code below. The cornerstone of C is
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* "programmer is always right" and that's what we love it for:-)
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* For this very reason C compilers have to be paranoid when it
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* comes to data aliasing and assume the worst. Yeah, but what
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* does it mean in real life? This means that loop body below will
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* be compiled to sequence of loads immediately followed by stores
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* as compiler assumes the worst, something in A==B+1 style. As a
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* result CPU pipeline is going to starve for incoming data. Secondly
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* if A and B happen to share same cache line such code is going to
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* cause severe cache trashing. Both factors have severe impact on
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* performance of modern CPUs and this is the reason why this
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* particular piece of code is #ifdefed away and replaced by more
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* "friendly" version found in #else section below. This comment
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* also applies to BN_copy function.
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*
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* <appro@fy.chalmers.se>
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*/
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for (i=b->top&(~7); i>0; i-=8)
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{
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A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3];
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A[4]=B[4]; A[5]=B[5]; A[6]=B[6]; A[7]=B[7];
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A+=8;
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B+=8;
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}
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switch (b->top&7)
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{
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case 7:
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A[6]=B[6];
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case 6:
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A[5]=B[5];
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case 5:
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A[4]=B[4];
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case 4:
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A[3]=B[3];
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case 3:
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A[2]=B[2];
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case 2:
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A[1]=B[1];
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case 1:
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A[0]=B[0];
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case 0:
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/* I need the 'case 0' entry for utrix cc.
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* If the optimizer is turned on, it does the
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* switch table by doing
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* a=top&7
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* a--;
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* goto jump_table[a];
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* If top is 0, this makes us jump to 0xffffffc
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* which is rather bad :-(.
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* eric 23-Apr-1998
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*/
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;
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}
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#else
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for (i=b->top>>2; i>0; i--,A+=4,B+=4)
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{
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/*
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* The fact that the loop is unrolled
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* 4-wise is a tribute to Intel. It's
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* the one that doesn't have enough
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* registers to accomodate more data.
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* I'd unroll it 8-wise otherwise:-)
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*
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* <appro@fy.chalmers.se>
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*/
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BN_ULONG a0,a1,a2,a3;
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a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
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A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
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}
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switch (b->top&3)
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{
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case 3: A[2]=B[2];
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case 2: A[1]=B[1];
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case 1: A[0]=B[0];
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case 0: ; /* ultrix cc workaround, see above */
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}
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#endif
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OPENSSL_free(b->d);
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}
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b->d=a;
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b->dmax=words;
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/* Now need to zero any data between b->top and b->max */
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A= &(b->d[b->top]);
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for (i=(b->dmax - b->top)>>3; i>0; i--,A+=8)
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{
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A[0]=0; A[1]=0; A[2]=0; A[3]=0;
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A[4]=0; A[5]=0; A[6]=0; A[7]=0;
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}
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for (i=(b->dmax - b->top)&7; i>0; i--,A++)
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A[0]=0;
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#else
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memset(A,0,sizeof(BN_ULONG)*(words+1));
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memcpy(A,b->d,sizeof(b->d[0])*b->top);
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b->d=a;
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b->max=words;
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#endif
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/* memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */
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/* { int i; for (i=b->max; i<words+1; i++) p[i]=i;} */
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}
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return(b);
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}
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BIGNUM *BN_dup(const BIGNUM *a)
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{
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BIGNUM *r;
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if (a == NULL) return NULL;
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bn_check_top(a);
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r=BN_new();
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if (r == NULL) return(NULL);
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return((BIGNUM *)BN_copy(r,a));
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}
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BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
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{
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int i;
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BN_ULONG *A;
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const BN_ULONG *B;
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bn_check_top(b);
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if (a == b) return(a);
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if (bn_wexpand(a,b->top) == NULL) return(NULL);
|
|
|
|
#if 1
|
|
A=a->d;
|
|
B=b->d;
|
|
for (i=b->top>>2; i>0; i--,A+=4,B+=4)
|
|
{
|
|
BN_ULONG a0,a1,a2,a3;
|
|
a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
|
|
A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
|
|
}
|
|
switch (b->top&3)
|
|
{
|
|
case 3: A[2]=B[2];
|
|
case 2: A[1]=B[1];
|
|
case 1: A[0]=B[0];
|
|
case 0: ; /* ultrix cc workaround, see comments in bn_expand2 */
|
|
}
|
|
#else
|
|
memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
|
|
#endif
|
|
|
|
/* memset(&(a->d[b->top]),0,sizeof(a->d[0])*(a->max-b->top));*/
|
|
a->top=b->top;
|
|
if ((a->top == 0) && (a->d != NULL))
|
|
a->d[0]=0;
|
|
a->neg=b->neg;
|
|
return(a);
|
|
}
|
|
|
|
void BN_clear(BIGNUM *a)
|
|
{
|
|
if (a->d != NULL)
|
|
memset(a->d,0,a->dmax*sizeof(a->d[0]));
|
|
a->top=0;
|
|
a->neg=0;
|
|
}
|
|
|
|
BN_ULONG BN_get_word(BIGNUM *a)
|
|
{
|
|
int i,n;
|
|
BN_ULONG ret=0;
|
|
|
|
n=BN_num_bytes(a);
|
|
if (n > sizeof(BN_ULONG))
|
|
return(BN_MASK2);
|
|
for (i=a->top-1; i>=0; i--)
|
|
{
|
|
#ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
|
|
ret<<=BN_BITS4; /* stops the compiler complaining */
|
|
ret<<=BN_BITS4;
|
|
#else
|
|
ret=0;
|
|
#endif
|
|
ret|=a->d[i];
|
|
}
|
|
return(ret);
|
|
}
|
|
|
|
int BN_set_word(BIGNUM *a, BN_ULONG w)
|
|
{
|
|
int i,n;
|
|
if (bn_expand(a,sizeof(BN_ULONG)*8) == NULL) return(0);
|
|
|
|
n=sizeof(BN_ULONG)/BN_BYTES;
|
|
a->neg=0;
|
|
a->top=0;
|
|
a->d[0]=(BN_ULONG)w&BN_MASK2;
|
|
if (a->d[0] != 0) a->top=1;
|
|
for (i=1; i<n; i++)
|
|
{
|
|
/* the following is done instead of
|
|
* w>>=BN_BITS2 so compilers don't complain
|
|
* on builds where sizeof(long) == BN_TYPES */
|
|
#ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
|
|
w>>=BN_BITS4;
|
|
w>>=BN_BITS4;
|
|
#else
|
|
w=0;
|
|
#endif
|
|
a->d[i]=(BN_ULONG)w&BN_MASK2;
|
|
if (a->d[i] != 0) a->top=i+1;
|
|
}
|
|
return(1);
|
|
}
|
|
|
|
/* ignore negative */
|
|
BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
|
|
{
|
|
unsigned int i,m;
|
|
unsigned int n;
|
|
BN_ULONG l;
|
|
|
|
if (ret == NULL) ret=BN_new();
|
|
if (ret == NULL) return(NULL);
|
|
l=0;
|
|
n=len;
|
|
if (n == 0)
|
|
{
|
|
ret->top=0;
|
|
return(ret);
|
|
}
|
|
if (bn_expand(ret,(int)(n+2)*8) == NULL)
|
|
return(NULL);
|
|
i=((n-1)/BN_BYTES)+1;
|
|
m=((n-1)%(BN_BYTES));
|
|
ret->top=i;
|
|
while (n-- > 0)
|
|
{
|
|
l=(l<<8L)| *(s++);
|
|
if (m-- == 0)
|
|
{
|
|
ret->d[--i]=l;
|
|
l=0;
|
|
m=BN_BYTES-1;
|
|
}
|
|
}
|
|
/* need to call this due to clear byte at top if avoiding
|
|
* having the top bit set (-ve number) */
|
|
bn_fix_top(ret);
|
|
return(ret);
|
|
}
|
|
|
|
/* ignore negative */
|
|
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
|
|
{
|
|
int n,i;
|
|
BN_ULONG l;
|
|
|
|
n=i=BN_num_bytes(a);
|
|
while (i-- > 0)
|
|
{
|
|
l=a->d[i/BN_BYTES];
|
|
*(to++)=(unsigned char)(l>>(8*(i%BN_BYTES)))&0xff;
|
|
}
|
|
return(n);
|
|
}
|
|
|
|
int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
int i;
|
|
BN_ULONG t1,t2,*ap,*bp;
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
i=a->top-b->top;
|
|
if (i != 0) return(i);
|
|
ap=a->d;
|
|
bp=b->d;
|
|
for (i=a->top-1; i>=0; i--)
|
|
{
|
|
t1= ap[i];
|
|
t2= bp[i];
|
|
if (t1 != t2)
|
|
return(t1 > t2?1:-1);
|
|
}
|
|
return(0);
|
|
}
|
|
|
|
int BN_cmp(const BIGNUM *a, const BIGNUM *b)
|
|
{
|
|
int i;
|
|
int gt,lt;
|
|
BN_ULONG t1,t2;
|
|
|
|
if ((a == NULL) || (b == NULL))
|
|
{
|
|
if (a != NULL)
|
|
return(-1);
|
|
else if (b != NULL)
|
|
return(1);
|
|
else
|
|
return(0);
|
|
}
|
|
|
|
bn_check_top(a);
|
|
bn_check_top(b);
|
|
|
|
if (a->neg != b->neg)
|
|
{
|
|
if (a->neg)
|
|
return(-1);
|
|
else return(1);
|
|
}
|
|
if (a->neg == 0)
|
|
{ gt=1; lt= -1; }
|
|
else { gt= -1; lt=1; }
|
|
|
|
if (a->top > b->top) return(gt);
|
|
if (a->top < b->top) return(lt);
|
|
for (i=a->top-1; i>=0; i--)
|
|
{
|
|
t1=a->d[i];
|
|
t2=b->d[i];
|
|
if (t1 > t2) return(gt);
|
|
if (t1 < t2) return(lt);
|
|
}
|
|
return(0);
|
|
}
|
|
|
|
int BN_set_bit(BIGNUM *a, int n)
|
|
{
|
|
int i,j,k;
|
|
|
|
i=n/BN_BITS2;
|
|
j=n%BN_BITS2;
|
|
if (a->top <= i)
|
|
{
|
|
if (bn_wexpand(a,i+1) == NULL) return(0);
|
|
for(k=a->top; k<i+1; k++)
|
|
a->d[k]=0;
|
|
a->top=i+1;
|
|
}
|
|
|
|
a->d[i]|=(((BN_ULONG)1)<<j);
|
|
return(1);
|
|
}
|
|
|
|
int BN_clear_bit(BIGNUM *a, int n)
|
|
{
|
|
int i,j;
|
|
|
|
i=n/BN_BITS2;
|
|
j=n%BN_BITS2;
|
|
if (a->top <= i) return(0);
|
|
|
|
a->d[i]&=(~(((BN_ULONG)1)<<j));
|
|
bn_fix_top(a);
|
|
return(1);
|
|
}
|
|
|
|
int BN_is_bit_set(const BIGNUM *a, int n)
|
|
{
|
|
int i,j;
|
|
|
|
if (n < 0) return(0);
|
|
i=n/BN_BITS2;
|
|
j=n%BN_BITS2;
|
|
if (a->top <= i) return(0);
|
|
return((a->d[i]&(((BN_ULONG)1)<<j))?1:0);
|
|
}
|
|
|
|
int BN_mask_bits(BIGNUM *a, int n)
|
|
{
|
|
int b,w;
|
|
|
|
w=n/BN_BITS2;
|
|
b=n%BN_BITS2;
|
|
if (w >= a->top) return(0);
|
|
if (b == 0)
|
|
a->top=w;
|
|
else
|
|
{
|
|
a->top=w+1;
|
|
a->d[w]&= ~(BN_MASK2<<b);
|
|
}
|
|
bn_fix_top(a);
|
|
return(1);
|
|
}
|
|
|
|
int bn_cmp_words(BN_ULONG *a, BN_ULONG *b, int n)
|
|
{
|
|
int i;
|
|
BN_ULONG aa,bb;
|
|
|
|
aa=a[n-1];
|
|
bb=b[n-1];
|
|
if (aa != bb) return((aa > bb)?1:-1);
|
|
for (i=n-2; i>=0; i--)
|
|
{
|
|
aa=a[i];
|
|
bb=b[i];
|
|
if (aa != bb) return((aa > bb)?1:-1);
|
|
}
|
|
return(0);
|
|
}
|
|
|