As the title says I'm trying to use PHP's password_hash function but I know that it is one way hashing so if I use it the password will be unable to be unhashed.
That being said, I want to be able to have an eye next to a password box (like LastPass) within the system that I'm working with that can display the password for admin users of the site but I'm not sure how to do this. Is there a function within PHP or some library that will allow for secure hashing or encryption so that this is possible? Is there another way to do this securely?
I've been looking around stack overflow for a while now just trying to find an answer to this but have to find anything that is close to what I'm wanting to do.
For a quick frame of reference for this. The users of the site can allow for 3rd party companies to login to retrieve files that are being shared with them. The users create the password and share it with the 3rd party. I want to make sure that when the passwords are secured but still allow the users of the site to go back and lookup the password for the 3rd party companies should they forget their password.
... that will allow for secure hashing or encryption so that [displaying the password for admin users] is possible?
You keep using that word. I do not think it means what you think it means. :-)
Password hashing can either be secure or it can be reversible.
The whole point of password hashing is to be non-reversible. If you want the original password, you're going to have to store it (keeping in mind how insecure this actually is).
At a bare minimum, you'd want the plaintext password somewhere totally separate from, and inaccessible to, the outside world. But the ground is littered from the corpses of password files that companies thought were secure from the general public, so my advice is to steer well clear of this.