about user authorization

[KFC]

I am writing a webpage which is only allowed the intranet users to access. I need an interface for logging. I believe that it is very easy to do it with PHP and mysql(managing the users' information). However, I am wondering if it is possible to load the system users and the information into the database. If so, how can I decrypt the password of the local system user in PHP.

[mtmosier]

However, I am wondering if it is possible to load the system users and the information into the database.

Depends upon the system. On windows I have no idea. On linux the users and passwords are usually stored in /etc/passwd or /etc/shadow (though it's possible to store them elsewhere).

If so, how can I decrypt the password of the local system user in PHP.

Generally speaking, you can't. System passwords are almost always stored in hashed format, which is one-way encryption. If you were talking about linux they're normally stored in a crypt compatible format. Tested it on my system, and that is the case here.

Edit - Also see this thread if you're running linux.