Allowing user to set password for form?

I have a performance evaluation form that has been rights-extended so users can save data typed into the form, but the users would like to be able to set their own passwords for security purposes. Is there any way to do this? My last resort I guess will be to just tell them to zip the pdf file into a password protected zip file, but I feel like there must be a way to script something in the doc:ready event??

Thanks,

Jo