字符串加密之后在解密

//字符串转换成16进制
/*
 * $str1为空参数，占位
 * */
function str2hex($str, $str1 = "", $encoded = 'GBK') {
    $hex = '';
    if ($encoded == 'GBK') {
        $str = mb_convert_encoding($str, 'GBK', 'UTF-8');
    }
    for ($i = 0, $length = mb_strlen($str); $i < $length; $i++) {
        $hex .= dechex(ord($str{$i}));
    }
    return $hex;
}

//16进制转换成字符串
function hex2str($hex, $encoded = 'GBK') {
    $str = '';
    $arr = str_split($hex, 2);
    foreach ($arr as $bit) {
        $str .= chr(hexdec($bit));
    }
    if ($encoded == 'GBK') {
        $str = mb_convert_encoding($str, 'UTF-8', 'GBK');
    }
    return $str;
}