PlanetScale

Hey all, Hoping that this is something that is possible with PHP as standard or can be added through a PHP extension. I would like to setup something similar to the Windows registry or a password keychain but for my PHP applications which will allow me to securely store usernames and passwords for accessing databases and remote servers without needing to have them stored in the file system where someone could get access to them by reading the source code of the PHP app. Is this possible or is there another option that will achieve something similar? Any pointers would be appreciated. Thanks.