Generate protected PDF contracts

I need to be able to generate contract documents by merging input from (a) a web form and/or (b) retrieving a record from MySQL database. If the initial input if from the web from, the data must be saved to the database for reuse at a later date if it is necessary to reprint the contract. Once generated, the pdf contract will need to be (a) saved to disk and/or (b) emailed to one or more parties. The pdf should be password protected once generated to prevent editing of contract language. The contracts have approximately 12 fields (contract date, company name, address, phone, delivery date, signers name and contact information, payment terms, etc.) I would prefer this be done with PHP and open source (like FPDF or similar) code. I can provide a template pdf and define the fields necessary for the contract. I also have the contract in HTML.