Electronic signature with password from hidden sheet and pdf final sheet only

Hi,

Need help with inserting a electronic signature for various users with unique password. The Signatures should be saved in a hidden protected sheet.
Data capturers insert the data into a data input sheet, the authorized users are the only ones that must be able to change data after the sheet has been created (from data capturers). Once all is in order the authorized user should type in a password to sign the sheet (signature should also be protected to prevent copying the forging of report forms).

Once signed it should have a function to save the sheet in pdf format, the sheet should also be saved but excluding the signature as forgetful minds don't always remove the electronic signature.

I know this is sort of a tall order, but any help would be appreciated.

Thanks
Anthony