I have a paranoid client asking me if I can encrypt the data on the .env.php file, he is uncomfortable with a "plain text" password stored on that file.

I know I can use server's environment variables on apache or nginx, but the password are stored as plain text on .conf files, so I think my client would not like this approach either, for the same reason: "plain text".

Other way is encrypt the values on that file, but it means I will need a KEY to decrypt that information and need to store that key on a plain text php file or env variable, so it's the same problem.

¿Is there another way to store sensitive data encrypted or something like that?