how do we encrypt data on the form?

Inside of this guides you can find how to encrypt your form: 

https://www.jotform.com/blog/162-Introducing-Encrypted-Forms-The-Ultimate-in-Online-Form-Security 

http://www.jotform.com/encrypted-forms 

https://www.jotform.com/help/344-Encrypted-Forms-and-How-to-Use-Them 

Hope this will help. Let us know if you need further assistance.