We will use an encryption called Vigenere. Although this kind of encryption
technique has not got any chance against
reversers, it will probably be more than enough to keep most lusers out.
The Vigenere cipher is easy to code and good enough to demonstrate
You will therefore be able to protect (somehow :-) your Web pages from unwelcome
visitors, once you elaborate on it a little.
The code is not originally mine: it is available on many sites of the web (that's the
cannot offer a reference to its real Author, too many haven copycatted it),
and I have -exactly like all other authors-
only slightly modified the original one: I have made it
case insensitive, have choosen an incredibly easy password (Hint: use "aaaaaaaaa" and see what
and have given you
a "one to one" relationship.It's actually dead easy as you will see, I even prepared a special "debug"
function for your experiments...
~ begin encrypted document ~
~ end encrypted document ~
Your page may begin with an unencrypted header, followed by
a section of script which contains five main elements:
a decryption function definition (try to follow the code); 2)
a string -as long as you fancy- of encrypted text ("ciphertext"); 3)
a few lines of code that prompt the user for a key; 4)
a call to the decryption function using the ciphertext and key as parameters; 5)
a write statement that outputs the string returned by the decryption function
The document ends with an unencrypted footer. However, you will not see
the unencrypted text unless you enter the correct password. The "View Source"
command won't help much, either, because the password is not contained in the
source and the text is scrambled.
Of course, you can encrypt your documents with nearly any encryption technique,
you started, here is the basic scripting pattern you should use in
// Copy the ciphertext into a string variable:
text = "jdiownvuizsponmwe";
// Obtain a password from the user:
password = get_password ();
// Use the password to unscramble the text.
text = decode (text, password);
// Display the result in the document:
document . write (text);
With a correct password (used as key) decoded text will
be written to the browser window. Otherwise, the output
will look like one to one (with Uppercase and lowercase
If you are going to encrypt many pages of your site, you could
you can load automatically with each page by setting the src
property of the <script> tag.
You are deep inside fravia's page of reverse engineering,
choose your way out:
Is reverse engineering legal?
Fravia 1995, 1996, 1997, 1998, 1999. All rights