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;
}