The applet shows a form that requests user's name and its password, loading from the server
a text file "lista.txt" ( The name of the file may be changed, it is one of the parameters
of the Applet). This file should be in the same directory of the server with the webpage that
contains the applet. This file has the following format:
Name Password webpage
Juan alfa page1.html
Pepe 12345 home.html
... ... ...
... ... ...
Each line contains an user, its password and the page to which can access. These three
elements should go separated for at least a white space and the data of the first line
of the file is ignored, for what can be used as header.
If the user and the password introduced through the applet matchs with some of the list,
the navigator loads the corresponding webpage.
One of the possible inconveniences of this process is that the file that contains the list of
users and their passwords, it is stored in the caché of the navigator, in the directory
"Temporary Internet Files" with can be readed by a hacker.
To avoid this inconvenience the file "lista.txt" can be encrypted using the applet
To use the encryption applet we should give it a number of 4 or 5 digits that will act as
a key in the code process. This same number will be sents as parameter to the Applet of
access control, so that it is able to code the data that the user introduces.
The previous file once encrypted (in this case with the number 8435) it is in the
following way :
Name Password webpage
L{eq crjd rgkh23ovsp
Rkth 38776 juqh/m{or
... ... ...
... ... ...
If we pass the value 0 by the parameter key, the applet considers that the file of keys
is not encrypted and therefore it omits the decoding process.