xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status==200) {
token=xhr.responseText;
//add value/field to form
txCvv = txJ$(".cvv").val();
var MyForm = txJ$(".submit").closest("form");
if (txJ$('#cipherText').length > 0) {
    txJ$('#cipherText').val(txCryptData);
}
else
{
    txJ$('<input type="hidden">').attr({
            id: 'token',
            name: 'token'
        }).val(token).appendTo(MyForm);
    txJ$('<input type="hidden">').attr({
            id: 'cvv',
            name: 'cvv'
        }).val(txCvv).appendTo(MyForm);



}

//scrub data that we do not want to post
txJ$(".data").removeAttr('name');
txJ$(".cvv").removeAttr('name');
    }
}
xhr.open('POST', 'tokenize.php', true);
xhr.send(params);

<?php
     $encrypted_data = file_get_contents("php://input");
    //There are some codes here.
    echo $output;
<?