I have 1 php file that need to be decrypted. I will only release payment after the decrypted files are proven to work as they did before they where decrypted. This means that I should be able to take the decrypted file and replace the existing encrypted file within and everything should continue to work as per normal without any errors showing.
Don't bid on this project if you feel it is beyond your skill set. I will upload one file for you to investigate after you have outlined your proposal.