Assignment #8a.

Your assignment if you choose this option is to construct an "encrypted" multi-
user chat client and server programs.

The client:
- Should accept a host and optionally a port # from the command line.
  i.e.: Usage: cclient <host> [<port#>]

- Should connect to the server using a streaming internet socket.  All
  communication with the server should be "encrypted" using a simple stream
  cipher using the rand_r() or better the lrand48_r() PRNG's.  The port number
  may be used as the secret key to the PRNG.

- Your client may handle the login/authorization phase and send the username and
  password to the server on connecting.  Note however that typed passwords
  should not be visible.

The server:
- Should allow multiple incoming streaming internet client connections that are
  individually encrypted using the secret key via a PRNG.  All messages that
  are received should be broadcast to all connected clients.  Each connected
  client should have their own PRNG seed.

- When a initial connection is made the server should enter into an
  authorization phase with the new client by either a) being sent the
  authorization information by the client or, b) prompting for a user-name, then
  password and check the credentials against a user-name/password database file
  "./auth.db" (that is located in the current working directory of the server.)

- The auth.db file should in the following format:

user-name1:hashed-password1
user-name2:hashed-password2
...

  The server should allow for more than one user-name and password. Note that
  the client should not echo keys typed in the password entry phase.

  Note also that I should be able to replace your auth.db file with my own when
  I test your programs, do not use hard-coded paths to your home directory when
  referencing any files.