Code Modify / Securing a Form

I am looking for a developer that can modify existing legacy code. We have a php form that uses cgi form processor that captures all the fields and saves it to a text file to a directory. The file that is written to uses a specific code to related to timecode to create new files (so it doesn't overwrite the file). The session is done via https. We would like this code to be more secure so that it is not readable and it prevents bots/scripts from flooding the form. I would like the code modify to be doing the following: 1) Session needs to expire after x amount of inactivity. 2) Captcha at the end of the form 3) The file that the cgi (may need replacing) writes needs to be encrypted(AES 256bit) and a admin end that will decrypt the file and allow printing of the file.