I am trying to make fillable documents for University Students and am unable ot easily utilize masking (if thats the right method) to have their social security # be asterisks except last 4. I saw another answer but the link suggested did not work for me. When the document is returned via email I can pull the numbers for their records.
You should not use that. It offers no protection at all. The full number can easily be extracted by anyone who has access to the file.
You must not have personal info submitted by mail. Not just SSN but names, emails, addresses. You must use a secure https script written by a web programming professional. In some countries there are very severe penalties for breaches.
I have met with our Web programmers and they stated the same. Thank you for your clear and concise comments.