What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
You could do that by using condition logic, but someone could overcome this if they know their way around the code of the page.
Now if you are still interested in that, you can do that by adding a password field (it should not be titled password because of our phishing filter).
Now go to conditions and set it to check if the field has the required password typed in or not and if it does, show everything.
You can see this in action here: http://form.jotformpro.com/form/42993451658972
If you would like to inspect it, you can check this tutorial here: How to Clone an Existing Form from a URL
Do let us if that works for you as well as if you have any further questions.