lib/libcrypt/md5crypt.c

   1 /*      $NetBSD: md5crypt.c,v 1.12 2012/08/30 12:16:49 drochner Exp $   */
   2
   3 /*
   4  * ----------------------------------------------------------------------------
   5  * "THE BEER-WARE LICENSE" (Revision 42):
   6  * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
   7  * can do whatever you want with this stuff. If we meet some day, and you think
   8  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   9  * ----------------------------------------------------------------------------
  10  *
  11  * from FreeBSD: crypt.c,v 1.5 1996/10/14 08:34:02 phk Exp
  12  * via OpenBSD: md5crypt.c,v 1.9 1997/07/23 20:58:27 kstailey Exp
  13  *
  14  */
  15
  16 #include <sys/cdefs.h>
  17 #if !defined(lint)
  18 __RCSID("$NetBSD: md5crypt.c,v 1.12 2012/08/30 12:16:49 drochner Exp $");
  19 #endif /* not lint */
  20
  21 #include <unistd.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <md5.h>
  25
  26 #include "crypt.h"
  27
  28 #define MD5_MAGIC       "$1$"
  29 #define MD5_MAGIC_LEN   3
  30
  31 #define INIT(x)                 MD5Init((x))
  32 #define UPDATE(x, b, l)         MD5Update((x), (b), (l))
  33 #define FINAL(v, x)             MD5Final((v), (x))
  34
  35
  36 /*
  37  * MD5 password encryption.
  38  */
  39 char *
  40 __md5crypt(const char *pw, const char *salt)
  41 {
  42         static char passwd[120], *p;
  43         const char *sp, *ep;
  44         unsigned char final[16];
  45         unsigned int i, sl, pwl;
  46         MD5_CTX ctx, ctx1;
  47         u_int32_t l;
  48         int pl;
  49
  50         pwl = strlen(pw);
  51
  52         /* Refine the salt first */
  53         sp = salt;
  54
  55         /* If it starts with the magic string, then skip that */
  56         if (strncmp(sp, MD5_MAGIC, MD5_MAGIC_LEN) == 0)
  57                 sp += MD5_MAGIC_LEN;
  58
  59         /* It stops at the first '$', max 8 chars */
  60         for (ep = sp; *ep != '\0' && *ep != '$' && ep < (sp + 8); ep++)
  61                 continue;
  62
  63         /* get the length of the true salt */
  64         sl = ep - sp;
  65
  66         INIT(&ctx);
  67
  68         /* The password first, since that is what is most unknown */
  69         UPDATE(&ctx, (const unsigned char *)pw, pwl);
  70
  71         /* Then our magic string */
  72         UPDATE(&ctx, (const unsigned char *)MD5_MAGIC, MD5_MAGIC_LEN);
  73
  74         /* Then the raw salt */
  75         UPDATE(&ctx, (const unsigned char *)sp, sl);
  76
  77         /* Then just as many characters of the MD5(pw,salt,pw) */
  78         INIT(&ctx1);
  79         UPDATE(&ctx1, (const unsigned char *)pw, pwl);
  80         UPDATE(&ctx1, (const unsigned char *)sp, sl);
  81         UPDATE(&ctx1, (const unsigned char *)pw, pwl);
  82         FINAL(final, &ctx1);
  83
  84         for (pl = pwl; pl > 0; pl -= 16)
  85                 UPDATE(&ctx, final, (unsigned int)(pl > 16 ? 16 : pl));
  86
  87         /* Don't leave anything around in vm they could use. */
  88         memset(final, 0, sizeof(final));
  89
  90         /* Then something really weird... */
  91         for (i = pwl; i != 0; i >>= 1)
  92                 if ((i & 1) != 0)
  93                     UPDATE(&ctx, final, 1);
  94                 else
  95                     UPDATE(&ctx, (const unsigned char *)pw, 1);
  96
  97         /* Now make the output string */
  98         memcpy(passwd, MD5_MAGIC, MD5_MAGIC_LEN);
  99         strlcpy(passwd + MD5_MAGIC_LEN, sp, sl + 1);
 100         strlcat(passwd, "$", sizeof(passwd));
 101
 102         FINAL(final, &ctx);
 103
 104         /* memset(&ctx, 0, sizeof(ctx)); done by MD5Final() */
 105
 106         /*
 107          * And now, just to make sure things don't run too fast. On a 60 MHz
 108          * Pentium this takes 34 msec, so you would need 30 seconds to build
 109          * a 1000 entry dictionary...
 110          */
 111         for (i = 0; i < 1000; i++) {
 112                 INIT(&ctx1);
 113
 114                 if ((i & 1) != 0)
 115                         UPDATE(&ctx1, (const unsigned char *)pw, pwl);
 116                 else
 117                         UPDATE(&ctx1, final, 16);
 118
 119                 if ((i % 3) != 0)
 120                         UPDATE(&ctx1, (const unsigned char *)sp, sl);
 121
 122                 if ((i % 7) != 0)
 123                         UPDATE(&ctx1, (const unsigned char *)pw, pwl);
 124
 125                 if ((i & 1) != 0)
 126                         UPDATE(&ctx1, final, 16);
 127                 else
 128                         UPDATE(&ctx1, (const unsigned char *)pw, pwl);
 129
 130                 FINAL(final, &ctx1);
 131         }
 132
 133         /* memset(&ctx1, 0, sizeof(ctx1)); done by MD5Final() */
 134
 135         p = passwd + sl + MD5_MAGIC_LEN + 1;
 136
 137         l = (final[ 0]<<16) | (final[ 6]<<8) | final[12]; __crypt_to64(p,l,4); p += 4;
 138         l = (final[ 1]<<16) | (final[ 7]<<8) | final[13]; __crypt_to64(p,l,4); p += 4;
 139         l = (final[ 2]<<16) | (final[ 8]<<8) | final[14]; __crypt_to64(p,l,4); p += 4;
 140         l = (final[ 3]<<16) | (final[ 9]<<8) | final[15]; __crypt_to64(p,l,4); p += 4;
 141         l = (final[ 4]<<16) | (final[10]<<8) | final[ 5]; __crypt_to64(p,l,4); p += 4;
 142         l =                    final[11]                ; __crypt_to64(p,l,2); p += 2;
 143         *p = '\0';
 144
 145         /* Don't leave anything around in vm they could use. */
 146         __explicit_bzero(final, sizeof(final));
 147         return (passwd);
 148 }