wordpress用户密码加密原理及其算法分析

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1、什么是wordpress？

关于wordpress的介绍请自行参照维基百科：http://zh.wikipedia.org/wiki/Wordpress

其实只要掌握了其加密原理，再用高效的语言实现之，暴力破解不就很容易了吗？

2、wordpress用户密码的加密算法

首先，wordpress是开源的，大家可以从官网下载源代码。另外wordpress是用php语言编写的。

wordpress用户密码加密后的密文格式：

$P$BcSda3/tRXQcRZMPj3cUI0jZJFdMgL0 
$P$BNclJc4wbM.vSjKPYxKggDPtw3siXQ0 

以下是其解压后文件夹/include下的class-phpass.php文件的代码，主要包含了对用户密码进行加密的类及函数；

<?php
/**
 * Portable PHP password hashing framework.
 * @package phpass
 * @since 2.5.0
 * @version 0.3 / WordPress
 * @link http://www.openwall.com/phpass/
 */

#
# Written by Solar Designer <solar at openwall.com> in 2004-2006 and placed in
# the public domain.  Revised in subsequent years, still public domain.
#
# There's absolutely no warranty.
#
# Please be sure to update the Version line if you edit this file in any way.
# It is suggested that you leave the main version number intact, but indicate
# your project name (after the slash) and add your own revision information.
#
# Please do not change the "private" password hashing method implemented in
# here, thereby making your hashes incompatible.  However, if you must, please
# change the hash type identifier (the "$P$") to something different.
#
# Obviously, since this code is in the public domain, the above are not
# requirements (there can be none), but merely suggestions.
#

/**
 * Portable PHP password hashing framework.
 *
 * @package phpass
 * @version 0.3 / WordPress
 * @link http://www.openwall.com/phpass/
 * @since 2.5.0
 */
class PasswordHash {
	var $itoa64;
	var $iteration_count_log2;
	var $portable_hashes;
	var $random_state;

	function PasswordHash($iteration_count_log2, $portable_hashes)
	{
		$this->itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';

		if ($iteration_count_log2 < 4 || $iteration_count_log2 > 31)
			$iteration_count_log2 = 8;
		$this->iteration_count_log2 = $iteration_count_log2;

		$this->portable_hashes = $portable_hashes;

		$this->random_state = microtime() . uniqid(rand(), TRUE); // removed getmypid() for compatibility reasons
	}

	function get_random_bytes($count)
	{
		$output = '';
		if ( @is_readable('/dev/urandom') &&
		    ($fh = @fopen('/dev/urandom', 'rb'))) {
			$output = fread($fh, $count);
			fclose($fh);
		}

		if (strlen($output) < $count) {
			$output = '';
			for ($i = 0; $i < $count; $i += 16) {
				$this->random_state =
				    md5(microtime() . $this->random_state);
				$output .=
				    pack('H*', md5($this->random_state));
			}
			$output = substr($output, 0, $count);
		}

		return $output;
	}

	function encode64($input, $count)
	{
		$output = '';
		$i = 0;
		do {
			$value = ord($input[$i++]);
			$output .= $this->itoa64[$value & 0x3f];
			if ($i < $count)
				$value |= ord($input[$i]) << 8;
			$output .= $this->itoa64[($value >> 6) & 0x3f];
			if ($i++ >= $count)
				break;
			if ($i < $count)
				$value |= ord($input[$i]) << 16;
			$output .= $this->itoa64[($value >> 12) & 0x3f];
			if ($i++ >= $count)
				break;
			$output .= $this->itoa64[($value >> 18) & 0x3f];
		} while ($i < $count);

		return $output;
	}

	function gensalt_private($input)
	{
		$output = '$P$';
		$output .= $this->itoa64[min($this->iteration_count_log2 +
			((PHP_VERSION >= '5') ? 5 : 3), 30)];
		$output .= $this->encode64($input, 6);

		return $output;
	}

	function crypt_private($password, $setting)
	{
		$output = '*0';
		if (substr($setting, 0, 2) == $output)
			$output = '*1';

		$id = substr($setting, 0, 3);
		# We use "$P$", phpBB3 uses &