crypto/bn/bn_mpi.c

   1 /* crypto/bn/bn_mpi.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 #include <stdio.h>
  60 #include "cryptlib.h"
  61 #include "bn_lcl.h"
  62
  63 int BN_bn2mpi(a,d)
  64 BIGNUM *a;
  65 unsigned char *d;
  66         {
  67         int bits;
  68         int num=0;
  69         int ext=0;
  70         long l;
  71
  72         bits=BN_num_bits(a);
  73         num=(bits+7)/8;
  74         if (bits > 0)
  75                 {
  76                 ext=((bits & 0x07) == 0);
  77                 }
  78         if (d == NULL)
  79                 return(num+4+ext);
  80
  81         l=num+ext;
  82         d[0]=(unsigned char)(l>>24)&0xff;
  83         d[1]=(unsigned char)(l>>16)&0xff;
  84         d[2]=(unsigned char)(l>> 8)&0xff;
  85         d[3]=(unsigned char)(l    )&0xff;
  86         if (ext) d[4]=0;
  87         num=BN_bn2bin(a,&(d[4+ext]));
  88         if (a->neg)
  89                 d[4]|=0x80;
  90         return(num+4+ext);
  91         }
  92
  93 BIGNUM *BN_mpi2bn(d,n,a)
  94 unsigned char *d;
  95 int n;
  96 BIGNUM *a;
  97         {
  98         long len;
  99         int neg=0;
 100
 101         if (n < 4)
 102                 {
 103                 BNerr(BN_F_BN_MPI2BN,BN_R_INVALID_LENGTH);
 104                 return(NULL);
 105                 }
 106         len=((long)d[0]<<24)|((long)d[1]<<16)|((int)d[2]<<8)|(int)d[3];
 107         if ((len+4) != n)
 108                 {
 109                 BNerr(BN_F_BN_MPI2BN,BN_R_ENCODING_ERROR);
 110                 return(NULL);
 111                 }
 112
 113         if (a == NULL) a=BN_new();
 114         if (a == NULL) return(NULL);
 115
 116         if (len == 0)
 117                 {
 118                 a->neg=0;
 119                 a->top=0;
 120                 return(a);
 121                 }
 122         d+=4;
 123         if ((*d) & 0x80)
 124                 neg=1;
 125         if (BN_bin2bn(d,(int)len,a) == NULL)
 126                 return(NULL);
 127         a->neg=neg;
 128         if (neg)
 129                 {
 130                 BN_clear_bit(a,BN_num_bits(a)-1);
 131                 }
 132         return(a);
 133         }
 134