php 加密、解密函数 (discuz)

摘要: php,加密,解密,discuz

1.php自带的加密扩展（需要安装mcrypt扩展）

function encrypt($plain_text) {
$key = 'f156a1f65e';
$plain_text = trim($plain_text);
$iv = substr(md5($key),0,mcrypt_get_iv_size(MCRYPT_CAST_256,MCRYPT_MODE_CFB));
$c_t = mcrypt_cfb (MCRYPT_CAST_256,$key,$plain_text,MCRYPT_ENCRYPT,$iv);
return trim(chop(base64_encode($c_t)));
}
function decrypt($c_t) {
$key = 'f156a1f65e';
$c_t = trim(chop(base64_decode($c_t)));
$iv = substr(md5($key),0,mcrypt_get_iv_size (MCRYPT_CAST_256,MCRYPT_MODE_CFB));
$p_t = mcrypt_cfb (MCRYPT_CAST_256,$key,$c_t,MCRYPT_DECRYPT,$iv);
return trim(chop($p_t));
}

/**
* 系统加密方法
* @param string $data 要加密的字符串
* @param string $key 加密密钥
* @param int $expire 过期时间 单位 秒
* @return string
* @author 麦当苗儿 <zuojiazi@vip.qq.com>
*/
function think_encrypt($data, $key = '', $expire = 0) {

$data = base64_encode($data);
$x = 0;
$len = strlen($data);
$l = strlen($key);
$char = '';

for ($i = 0; $i < $len; $i++) {
if ($x == $l) $x = 0;
$char .= substr($key, $x, 1);
$x++;
}

$str = sprintf('%010d', $expire ? $expire + time():0);

for ($i = 0; $i < $len; $i++) {
$str .= chr(ord(substr($data, $i, 1)) + (ord(substr($char, $i, 1)))%256);
}
return str_replace(array('+','/','='),array('-','_',''),base64_encode($str));
}

/**
* 系统解密方法
* @param string $data 要解密的字符串 （必须是think_encrypt方法加密的字符串）
* @param string $key 加密密钥
* @return string
* @author 麦当苗儿 <zuojiazi@vip.qq.com>
*/
function think_decrypt($data, $key = ''){

$data = str_replace(array('-','_'),array('+','/'),$data);
$mod4 = strlen($data) % 4;
if ($mod4) {
$data .= substr('====', $mod4);
}
$data = base64_decode($data);
$expire = substr($data,0,10);
$data = substr($data,10);

if($expire > 0 && $expire < time()) {
return '';
}
$x = 0;
$len = strlen($data);
$l = strlen($key);
$char = $str = '';

for ($i = 0; $i < $len; $i++) {
if ($x == $l) $x = 0;
$char .= substr($key, $x, 1);
$x++;
}

for ($i = 0; $i < $len; $i++) {
if (ord(substr($data, $i, 1))<ord(substr($char, $i, 1))) {
$str .= chr((ord(substr($data, $i, 1)) + 256) - ord(substr($char, $i, 1)));
}else{
$str .= chr(ord(substr($data, $i, 1)) - ord(substr($char, $i, 1)));
}
}
return base64_decode($str);
}