postfixadmin忘记密码后的修改密码方法详解

<?php
echo md5crypt("新密码");
// md5crypt
// Action: Creates MD5 encrypted password
// Call: md5crypt (string cleartextpassword)
function md5crypt($pw, $salt = "", $magic = "")
{
  $MAGIC = "$1$";
  if ($magic == "")
  {
    $magic = $MAGIC;
  }
  if ($salt == "")
  {
    $salt = create_salt();
  }
  $slist = explode("$", $salt);
  if (isset($slist[0]) && $slist[0] == "1")
  {
    $salt = $slist[1];
  }
  $salt = substr($salt, 0, 8);
  $ctx = $pw.$magic.$salt;
  $final = hex2bin(md5($pw.$salt.$pw));
  for ($i = strlen($pw); $i > 0; $i -= 16)
  {
    if ($i > 16)
    {
      $ctx .= substr($final,0,16);
    }
    else
    {
      $ctx .= substr($final,0,$i);
    }
  }
  $i = strlen($pw);
  while ($i > 0)
  {
    if ($i & 1)
    {
      $ctx .= chr(0);
    }
    else
    {
      $ctx .= $pw[0];
    }
    $i = $i >> 1;
  }
  $final = hex2bin(md5($ctx));
  for ($i=0; $i<1000; $i++)
  {
    $ctx1 = "";
    if ($i & 1)
    {
      $ctx1 .= $pw;
    }
    else
    {
      $ctx1 .= substr($final,0,16);
    }
    if ($i % 3)
    {
      $ctx1 .= $salt;
    }
    if ($i % 7)
    {
      $ctx1 .= $pw;
    }
    if ($i & 1)
    {
      $ctx1 .= substr($final, 0, 16);
    }
    else
    {
      $ctx1 .= $pw;
    }
    $final = hex2bin(md5($ctx1));
  }
  $passwd = "";
  $passwd .= to64(((ord($final[0]) << 16) | (ord($final[6]) << 8) | (ord($final[12]))), 4);
  $passwd .= to64(((ord($final[1]) << 16) | (ord($final[7]) << 8) | (ord($final[13]))), 4);
  $passwd .= to64(((ord($final[2]) << 16) | (ord($final[8]) << 8) | (ord($final[14]))), 4);
  $passwd .= to64(((ord($final[3]) << 16) | (ord($final[9]) << 8) | (ord($final[15]))), 4);
  $passwd .= to64(((ord($final[4]) << 16) | (ord($final[10]) << 8) | (ord($final[5]))), 4);
  $passwd .= to64(ord($final[11]), 2);
  return $magic.$salt.'$'.$passwd;
}
function create_salt()
{
  srand((double) microtime() * 1000000);
  return substr(md5(rand(0,9999999)), 0, 8);
}
// PHP around 5.3.8 includes hex2bin as native function - http://php.net/hex2bin
function hex2bin($str)
{
    $len = strlen($str);
    $nstr = "";
    for ($i = 0; $i < $len; $i += 2)
    {
      $num = sscanf(substr($str, $i, 2), "%x");
      $nstr .= chr($num[0]);
    }
    return $nstr;
}
function to64($v, $n)
{
  $ITOA64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  $ret = "";
  while (($n - 1) >= 0)
  {
    $n--;
    $ret .= $ITOA64[$v & 0x3f];
    $v = $v >> 6;
  }
  return $ret;
}