text: /*
   * ----------------------------------------------------------------------------
   * "THE BEER-WARE LICENSE" (Revision 42):
   * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
   * can do whatever you want with this stuff. If we meet some day, and you think
   * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   * ----------------------------------------------------------------------------
   */
  
  /*
   * Ported from FreeBSD to Linux, only minimal changes.  --marekm
   */
  
  /*
   * Adapted from shadow-19990607 by Tudor Bosman, tudorb@jm.nu
   */
  
  #include "lib.h"
  #include "safe-memset.h"
  #include "str.h"
  #include "md5.h"
  #include "password-scheme.h"
  
  static unsigned char itoa64[] =		/* 0 ... 63 => ascii - 64 */
  	"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  
  static char	magic[] = "$1$";	/*
  				 * This string is magic for
  				 * this algorithm.  Having
  				 * it this way, we can get
  				 * get better later on
  				 */
  
  static void
  to64(string_t *str, unsigned long v, int n)
  {
  	while (--n >= 0) {
  		str_append_c(str, itoa64[v&0x3f]);
  		v >>= 6;
  	}
  }
  
  /*
   * UNIX password
   *
   * Use MD5 for what it is best at...
   */
  
  const char *password_generate_md5_crypt(const char *pw, const char *salt)
  {
  	const char *sp,*ep;
  	unsigned char	final[MD5_RESULTLEN];
  	int sl,pl,i,j;
  	struct md5_context ctx,ctx1;
  	unsigned long l;
  	string_t *passwd;
  	size_t pw_len = strlen(pw);
  
  	/* Refine the Salt first */
  	sp = salt;
  
  	/* If it starts with the magic string, then skip that */
  	if (strncmp(sp, magic, sizeof(magic)-1) == 0)
  		sp += sizeof(magic)-1;
  
  	/* It stops at the first '$', max 8 chars */
  	for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++)
  		continue;
  
  	/* get the length of the true salt */
  	sl = ep - sp;
  
  	md5_init(&ctx);
  
  	/* The password first, since that is what is most unknown */
  	md5_update(&ctx,pw,pw_len);
  
  	/* Then our magic string */
  	md5_update(&ctx,magic,sizeof(magic)-1);
  
  	/* Then the raw salt */
  	md5_update(&ctx,sp,sl);
  
  	/* Then just as many characters of the MD5(pw,salt,pw) */
  	md5_init(&ctx1);
  	md5_update(&ctx1,pw,pw_len);
  	md5_update(&ctx1,sp,sl);
  	md5_update(&ctx1,pw,pw_len);
  	md5_final(&ctx1,final);
  	for(pl = pw_len; pl > 0; pl -= MD5_RESULTLEN)
  		md5_update(&ctx,final,pl>MD5_RESULTLEN ? MD5_RESULTLEN : pl);
  
  	/* Don't leave anything around in vm they could use. */
  	safe_memset(final, 0, sizeof(final));
  
  	/* Then something really weird... */
  	for (j=0,i = pw_len; i ; i >>= 1)
  		if(i&1)
  		    md5_update(&ctx, final+j, 1);
  		else
  		    md5_update(&ctx, pw+j, 1);
  
  	/* Now make the output string */
  	passwd = t_str_new(sl + 64);
  	str_append(passwd, magic);
  	str_append_n(passwd, sp, sl);
  	str_append_c(passwd, '$');
  
  	md5_final(&ctx,final);
  
  	/*
  	 * and now, just to make sure things don't run too fast
  	 * On a 60 Mhz Pentium this takes 34 msec, so you would
  	 * need 30 seconds to build a 1000 entry dictionary...
  	 */
  	for(i=0;i<1000;i++) {
  		md5_init(&ctx1);
  		if(i & 1)
  			md5_update(&ctx1,pw,pw_len);
  		else
  			md5_update(&ctx1,final,MD5_RESULTLEN);
  
  		if(i % 3)
  			md5_update(&ctx1,sp,sl);
  
  		if(i % 7)
  			md5_update(&ctx1,pw,pw_len);
  
  		if(i & 1)
  			md5_update(&ctx1,final,MD5_RESULTLEN);
  		else
  			md5_update(&ctx1,pw,pw_len);
  		md5_final(&ctx1,final);
  	}
  
  	l = (final[ 0]<<16) | (final[ 6]<<8) | final[12]; to64(passwd,l,4);
  	l = (final[ 1]<<16) | (final[ 7]<<8) | final[13]; to64(passwd,l,4);
  	l = (final[ 2]<<16) | (final[ 8]<<8) | final[14]; to64(passwd,l,4);
  	l = (final[ 3]<<16) | (final[ 9]<<8) | final[15]; to64(passwd,l,4);
  	l = (final[ 4]<<16) | (final[10]<<8) | final[ 5]; to64(passwd,l,4);
  	l =                    final[11]                ; to64(passwd,l,2);
  
  	/* Don't leave anything around in vm they could use. */
  	safe_memset(final, 0, sizeof(final));
  
  	return str_c(passwd);
  }
  