encrypt加密 decrypt解密 函数

/**
* 加密函数
* @param   string  $str    加密前的字符串
* @param   string  $key    密钥
* @return  string  加密后的字符串
*/
function encrypt($str, $key = AUTH_KEY)
{
$coded = '';
$keylength = strlen($key);

for ($i = 0, $count = strlen($str); $i < $count; $i += $keylength)
{
$coded .= substr($str, $i, $keylength) ^ $key;
}

return str_replace('=', '', base64_encode($coded));
}

/**
* 解密函数
* @param   string  $str    加密后的字符串
* @param   string  $key    密钥
* @return  string  加密前的字符串
*/
function decrypt($str, $key = AUTH_KEY)
{
$coded = '';
$keylength = strlen($key);
$str = base64_decode($str);

for ($i = 0, $count = strlen($str); $i < $count; $i += $keylength)
{
$coded .= substr($str, $i, $keylength) ^ $key;
}

return $coded;
}