Home | History | Annotate | Line # | Download | only in libcrypt
md5crypt.c revision 1.3 
      1 /*	$NetBSD: md5crypt.c,v 1.3 2000/12/03 13:01:37 ad Exp $	*/
      2 
      3 /*
      4  * ----------------------------------------------------------------------------
      5  * "THE BEER-WARE LICENSE" (Revision 42):
      6  * <phk (at) 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 1.3 2000/12/03 13:01:37 ad Exp $");
     19 #endif /* not lint */
     20 
     21 #include <unistd.h>
     22 #include <stdio.h>
     23 #include <string.h>
     24 #include <md5.h>
     25 #include <string.h>
     26 
     27 #define MD5_MAGIC	"$1$"
     28 #define MD5_MAGIC_LEN	3
     29 
     30 char	*__md5crypt(const char *pw, const char *salt);	/* XXX */
     31 
     32 static unsigned char itoa64[] =		/* 0 ... 63 => ascii - 64 */
     33 	"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
     34 
     35 static void to64(char *, u_int32_t, int);
     36 
     37 static void
     38 to64(char *s, u_int32_t v, int n)
     39 {
     40 
     41 	while (--n >= 0) {
     42 		*s++ = itoa64[v & 0x3f];
     43 		v >>= 6;
     44 	}
     45 }
     46 
     47 /*
     48  * MD5 password encryption.
     49  */
     50 char *
     51 __md5crypt(const char *pw, const char *salt)
     52 {
     53 	static char passwd[120], *p;
     54 	const char *sp, *ep;
     55 	unsigned char final[16];
     56 	unsigned int i, sl, pwl;
     57 	MD5_CTX	ctx, ctx1;
     58 	u_int32_t l;
     59 	int pl;
     60 
     61 	pwl = strlen(pw);
     62 
     63 	/* Refine the salt first */
     64 	sp = salt;
     65 
     66 	/* If it starts with the magic string, then skip that */
     67 	if (strncmp(sp, MD5_MAGIC, MD5_MAGIC_LEN) == 0)
     68 		sp += MD5_MAGIC_LEN;
     69 
     70 	/* It stops at the first '$', max 8 chars */
     71 	for (ep = sp; *ep != '\0' && *ep != '$' && ep < (sp + 8); ep++)
     72 		continue;
     73 
     74 	/* get the length of the true salt */
     75 	sl = ep - sp;
     76 
     77 	MD5Init(&ctx);
     78 
     79 	/* The password first, since that is what is most unknown */
     80 	MD5Update(&ctx, (const unsigned char *)pw, pwl);
     81 
     82 	/* Then our magic string */
     83 	MD5Update(&ctx, (const unsigned char *)MD5_MAGIC, MD5_MAGIC_LEN);
     84 
     85 	/* Then the raw salt */
     86 	MD5Update(&ctx, (const unsigned char *)sp, sl);
     87 
     88 	/* Then just as many characters of the MD5(pw,salt,pw) */
     89 	MD5Init(&ctx1);
     90 	MD5Update(&ctx1, (const unsigned char *)pw, pwl);
     91 	MD5Update(&ctx1, (const unsigned char *)sp, sl);
     92 	MD5Update(&ctx1, (const unsigned char *)pw, pwl);
     93 	MD5Final(final, &ctx1);
     94 
     95 	for (pl = pwl; pl > 0; pl -= 16)
     96 		MD5Update(&ctx, final, (unsigned int)(pl > 16 ? 16 : pl));
     97 
     98 	/* Don't leave anything around in vm they could use. */
     99 	memset(final, 0, sizeof(final));
    100 
    101 	/* Then something really weird... */
    102 	for (i = pwl; i != 0; i >>= 1)
    103 		if ((i & 1) != 0)
    104 		    MD5Update(&ctx, final, 1);
    105 		else
    106 		    MD5Update(&ctx, (const unsigned char *)pw, 1);
    107 
    108 	/* Now make the output string */
    109 	memcpy(passwd, MD5_MAGIC, MD5_MAGIC_LEN);
    110 	strncpy(passwd + MD5_MAGIC_LEN, sp, sl);
    111 	strcat(passwd, "$");
    112 
    113 	MD5Final(final, &ctx);
    114 
    115 	/*
    116 	 * And now, just to make sure things don't run too fast. On a 60 MHz
    117 	 * Pentium this takes 34 msec, so you would need 30 seconds to build
    118 	 * a 1000 entry dictionary...
    119 	 */
    120 	for (i = 0; i < 1000; i++) {
    121 		MD5Init(&ctx1);
    122 
    123 		if ((i & 1) != 0)
    124 			MD5Update(&ctx1, (const unsigned char *)pw, pwl);
    125 		else
    126 			MD5Update(&ctx1, final, 16);
    127 
    128 		if ((i % 3) != 0)
    129 			MD5Update(&ctx1, (const unsigned char *)sp, sl);
    130 
    131 		if ((i % 7) != 0)
    132 			MD5Update(&ctx1, (const unsigned char *)pw, pwl);
    133 
    134 		if ((i & 1) != 0)
    135 			MD5Update(&ctx1, final, 16);
    136 		else
    137 			MD5Update(&ctx1, (const unsigned char *)pw, pwl);
    138 
    139 		MD5Final(final, &ctx1);
    140 	}
    141 
    142 	p = passwd + sl + MD5_MAGIC_LEN + 1;
    143 
    144 	l = (final[ 0]<<16) | (final[ 6]<<8) | final[12]; to64(p,l,4); p += 4;
    145 	l = (final[ 1]<<16) | (final[ 7]<<8) | final[13]; to64(p,l,4); p += 4;
    146 	l = (final[ 2]<<16) | (final[ 8]<<8) | final[14]; to64(p,l,4); p += 4;
    147 	l = (final[ 3]<<16) | (final[ 9]<<8) | final[15]; to64(p,l,4); p += 4;
    148 	l = (final[ 4]<<16) | (final[10]<<8) | final[ 5]; to64(p,l,4); p += 4;
    149 	l =		       final[11]		; to64(p,l,2); p += 2;
    150 	*p = '\0';
    151 
    152 	/* Don't leave anything around in vm they could use. */
    153 	memset(final, 0, sizeof(final));
    154 	return (passwd);
    155 }
    156