PHP加密解密类(密文只有大小写字母和数字)，支持中文加密

<?php
/**
* MrPmvc加密解密类
* @author 狂奔的蜗牛
* @email  672308444@163.com
* @version alpha
* Usage:
*      $key = new KEY('adfasdfs', 30);
$e_txt = $key->encode('中文哦..aaaa');
echo $e_txt.'<br/>';
echo $key->decode($e_txt);
*/
class KEY {
private $expire = 0, $key = 'secret';

public function __construct($key_str = null, $time_to_live = null) {
if ($key_str) {
self::setKey($key_str);
}
if ($time_to_live) {
self::setExpire($time_to_live);
}
}

public  function setExpire($time_to_live) {
$this->expire = floatval($time_to_live);
}

public  function setKey($key_str) {
$this->key = (string) $key_str;
}

public  function encode($tex, $key = null, $expire = 0) {
$key = $key ? $key : $this->key;
$expire = $expire ? $expire : $this->expire;
$chrArr = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9');
$tex.="~#~" . sprintf('%010d', $expire ? $expire + time() : 0) . "~#~";
$key_b = $chrArr[rand() % 62] . $chrArr[rand() % 62] . $chrArr[rand() % 62] . $chrArr[rand() % 62] . $chrArr[rand() % 62] . $chrArr[rand() % 62];
$rand_key = $key_b . $key;
$rand_key = md5($rand_key);
$texlen = strlen($tex);
$reslutstr = "";
for ($i = 0; $i < $texlen; $i++) {
$reslutstr.=$tex{$i} ^ $rand_key{$i % 32};
}
$reslutstr = trim($key_b . base64_encode($reslutstr), "==");
$reslutstr = substr(md5($reslutstr), 0, 8) . $reslutstr;
return $reslutstr;
}

public  function decode($tex, $key = null) {
$key = $key ? $key : $this->key;
if (strlen($tex) < 14)
return false;
$verity_str = substr($tex, 0, 8);
$tex = substr($tex, 8);
if ($verity_str != substr(md5($tex), 0, 8)) {
//完整性验证失败
return false;
}
$key_b = substr($tex, 0, 6);
$rand_key = $key_b . $key;
$rand_key = md5($rand_key);
$tex = base64_decode(substr($tex, 6));
$texlen = strlen($tex);
$reslutstr = "";
for ($i = 0; $i < $texlen; $i++) {
$reslutstr.=$tex{$i} ^ $rand_key{$i % 32};
}
$expiry_arr = array();
preg_match('/^(.*)~#~(\d{10})~#~$/', $reslutstr, $expiry_arr);
if (count($expiry_arr) != 3) {
//过期时间完整性验证失败
return false;
} else {
$tex_time = $expiry_arr[2];
if ($tex_time > 0 && $tex_time - time() <= 0) {
//验证码过期
return false;
} else {
$reslutstr = $expiry_arr[1];
}
}
return $reslutstr;
}

}