Postgre user without password and PHP

I have a PostgreSQL database with a user and a database owned by that user. A local program written in C uses that user to manipulate that database without a password. I want to use HTML and PHP to create a web interface to access that database.

I've read conflicting things about PostgreSQL and using it without passwords. I also don't want to interfere with the way the current software is accessing and manipulating the database without a password.

Do I simply add a password for that user to use as log-in information for the PHP queries? Is there a better way to securely access that database through PHP?