lib/libcrypt/crypt-md5.c

   1 /*
   2  * ----------------------------------------------------------------------------
   3  * "THE BEER-WARE LICENSE" (Revision 42):
   4  * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
   5  * can do whatever you want with this stuff. If we meet some day, and you think
   6  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   7  * ----------------------------------------------------------------------------
   8  *
   9  * $FreeBSD: src/lib/libcrypt/crypt-md5.c,v 1.5.2.1 2001/05/24 12:20:02 markm Exp $
  10  * $DragonFly: src/lib/libcrypt/crypt-md5.c,v 1.3 2005/08/04 19:27:09 drhodus Exp $
  11  */
  12
  13 #include <unistd.h>
  14 #include <stdio.h>
  15 #include <string.h>
  16 #include <md5.h>
  17 #include <err.h>
  18 #include "crypt.h"
  19
  20 /*
  21  * UNIX password
  22  */
  23
  24 char *
  25 crypt_md5(const char *pw, const char *salt)
  26 {
  27         static char     *magic = "$1$"; /*
  28                                          * This string is magic for
  29                                          * this algorithm.  Having
  30                                          * it this way, we can get
  31                                          * get better later on
  32                                          */
  33         static char     passwd[120], *p;
  34         static const char *sp,*ep;
  35         unsigned char   final[MD5_SIZE];
  36         int sl,pl,i;
  37         MD5_CTX ctx,ctx1;
  38         unsigned long l;
  39
  40         /* Refine the Salt first */
  41         sp = salt;
  42
  43         /* If it starts with the magic string, then skip that */
  44         if(!strncmp(sp,magic,strlen(magic)))
  45                 sp += strlen(magic);
  46
  47         /* It stops at the first '$', max 8 chars */
  48         for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++)
  49                 continue;
  50
  51         /* get the length of the true salt */
  52         sl = ep - sp;
  53
  54         MD5Init(&ctx);
  55
  56         /* The password first, since that is what is most unknown */
  57         MD5Update(&ctx,pw,strlen(pw));
  58
  59         /* Then our magic string */
  60         MD5Update(&ctx,magic,strlen(magic));
  61
  62         /* Then the raw salt */
  63         MD5Update(&ctx,sp,sl);
  64
  65         /* Then just as many characters of the MD5(pw,salt,pw) */
  66         MD5Init(&ctx1);
  67         MD5Update(&ctx1,pw,strlen(pw));
  68         MD5Update(&ctx1,sp,sl);
  69         MD5Update(&ctx1,pw,strlen(pw));
  70         MD5Final(final,&ctx1);
  71         for(pl = strlen(pw); pl > 0; pl -= MD5_SIZE)
  72                 MD5Update(&ctx,final,pl>MD5_SIZE ? MD5_SIZE : pl);
  73
  74         /* Don't leave anything around in vm they could use. */
  75         memset(final,0,sizeof final);
  76
  77         /* Then something really weird... */
  78         for (i = strlen(pw); i ; i >>= 1)
  79                 if(i&1)
  80                     MD5Update(&ctx, final, 1);
  81                 else
  82                     MD5Update(&ctx, pw, 1);
  83
  84         /* Now make the output string */
  85         strcpy(passwd,magic);
  86         strncat(passwd,sp,sl);
  87         strcat(passwd,"$");
  88
  89         MD5Final(final,&ctx);
  90
  91         /*
  92          * and now, just to make sure things don't run too fast
  93          * On a 60 Mhz Pentium this takes 34 msec, so you would
  94          * need 30 seconds to build a 1000 entry dictionary...
  95          */
  96         for(i=0;i<1000;i++) {
  97                 MD5Init(&ctx1);
  98                 if(i & 1)
  99                         MD5Update(&ctx1,pw,strlen(pw));
 100                 else
 101                         MD5Update(&ctx1,final,MD5_SIZE);
 102
 103                 if(i % 3)
 104                         MD5Update(&ctx1,sp,sl);
 105
 106                 if(i % 7)
 107                         MD5Update(&ctx1,pw,strlen(pw));
 108
 109                 if(i & 1)
 110                         MD5Update(&ctx1,final,MD5_SIZE);
 111                 else
 112                         MD5Update(&ctx1,pw,strlen(pw));
 113                 MD5Final(final,&ctx1);
 114         }
 115
 116         p = passwd + strlen(passwd);
 117
 118         l = (final[ 0]<<16) | (final[ 6]<<8) | final[12];
 119         _crypt_to64(p,l,4); p += 4;
 120         l = (final[ 1]<<16) | (final[ 7]<<8) | final[13];
 121         _crypt_to64(p,l,4); p += 4;
 122         l = (final[ 2]<<16) | (final[ 8]<<8) | final[14];
 123         _crypt_to64(p,l,4); p += 4;
 124         l = (final[ 3]<<16) | (final[ 9]<<8) | final[15];
 125         _crypt_to64(p,l,4); p += 4;
 126         l = (final[ 4]<<16) | (final[10]<<8) | final[ 5];
 127         _crypt_to64(p,l,4); p += 4;
 128         l =                    final[11]                ;
 129         _crypt_to64(p,l,2); p += 2;
 130         *p = '\0';
 131
 132         /* Don't leave anything around in vm they could use. */
 133         memset(final,0,sizeof final);
 134
 135         return passwd;
 136 }
 137