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      1 /*	$NetBSD: md5crypt.c,v 1.16 2024/07/23 22:37:11 riastradh 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 1.16 2024/07/23 22:37:11 riastradh 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 crypt_private 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_memset(final, 0, sizeof(final));
    147 	return (passwd);
    148 }
    149