PHP 加密/解密函数 dencrypt(动态密文，带压缩功能，支持中文)

// +----------------------------------------------------------------------+ 
// | Willko Framework | 
// +----------------------------------------------------------------------+ 
// | Copyright (c) 2008-2009 Willko Cheng | 
// +----------------------------------------------------------------------+ 
// | Authors: Willko Cheng <[e-mail]> | 
// +----------------------------------------------------------------------+ 
// $string 明文 或 密文 
// $isEncrypt 是否加密 
// $key 密匙 
// 采用SHA1生成密匙簿，超过300个字符使用ZLIB压缩 
function dencrypt($string, $isEncrypt = true, $key = KEY_SPACE) { 
if (!isset($string{0}) || !isset($key{0})) { 
return false; 
} $dynKey = $isEncrypt ? hash('sha1', microtime(true)) : substr($string, 0, 40); 
$fixedKey = hash('sha1', $key); 
$dynKeyPart1 = substr($dynKey, 0, 20); 
$dynKeyPart2 = substr($dynKey, 20); 
$fixedKeyPart1 = substr($fixedKey, 0, 20); 
$fixedKeyPart2 = substr($fixedKey, 20); 
$key = hash('sha1', $dynKeyPart1 . $fixedKeyPart1 . $dynKeyPart2 . $fixedKeyPart2); 
$string = $isEncrypt ? $fixedKeyPart1 . $string . $dynKeyPart2 : (isset($string{339}) ? gzuncompress(base64_decode(substr($string, 40))) : base64_decode(substr($string, 40))); 
$n = 0; 
$result = ''; 
$len = strlen($string); 
for ($n = 0; $n < $len; $n++) { 
$result .= chr(ord($string{$n}) ^ ord($key{$n % 40})); 
} 
return $isEncrypt ? $dynKey . str_replace('=', '', base64_encode($n > 299 ? gzcompress($result) : $result)) : substr($result, 20, -20); 
}