“How to change the user's password.”

Every user has its own file in your users folder. The filename is an sha512 hash of the lowercase version of whatever the user’s name is. Inside the file you will find an sha512 hash of the user’s password (salted with the user’s name hash).

As the forum admin you have access to the files on the server and can just swap out the hash with a new one.

As a hint, there are plenty of websites that can help you hash strings. DuckDuckGo even has it built-in: https://duckduckgo.com/?q=sha512+Test

“This is no encryption.”

No, it is a hash, not even a very secure one 😉

Your example is right, user `admin` would have their password stored in `c7ad44cbad762a5da0a452f9e854fdc1e0e7a52a38015f23f3eab1d80b931dd472634dfac71cd34ebc35d16ab7fb8a90c81f975113d6c7538dc69dd8de9077ec.txt`.

The password is hashed together with the username hash, using this code:

% from start.php
hash ('sha512', $name.PASS)
%

So if the user `admin` has the word `admin` as password this is hashed like:

`c7ad44cbad762a5da0a452f9e854fdc1e0e7a52a38015f23f3eab1d80b931dd472634dfac71cd34ebc35d16ab7fb8a90c81f975113d6c7538dc69dd8de9077ecadmin` → `cf0f0304684d2f9dd35bd544c01a93087c6e1d8b441996aa0dcc91291a79dfd2fcb2861df8bdd92c2216c4a1c2ba194e42439d91e4f96a2449af0f91aa5a1d96`

I hope that explain it!