ROT-13 encrypt / decrypt (Caesar cipher)

ROT13 is its own inverse that is, to undo ROT13, the same algorithm is applied, so the same action can be used for encoding and decoding. The algorithm provides minimal cryptographic security, and is often cited as a canonical example of weak encryption. ROT13 has inspired a variety of letter and word games on-line, and is frequently mentioned in newsgroup conversations.
for demo see here
source code ROT-13 encrypt / decrypt (Caesar cipher):

<html> <head> <title>Encode / Decode ROT13 cipher</title> </head> <body> <script language="JavaScript"> function rot_13(obj) {   var keycode = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"   var text    = new String(obj.form.Text.value)   var rot13 = new String()    for(var i = 0; i < text.length; i++)   {     var codechar = text.substring(i, i + 1)     var pos = keycode.indexOf(codechar.toUpperCase())      if(pos >= 0)     {       pos      = (pos + keycode.length / 2) % keycode.length       codechar = (codechar == codechar.toUpperCase()) ?                  keycode.substring(pos, pos + 1) :                  keycode.substring(pos, pos + 1).toLowerCase()     }     rot13 = rot13 + codechar   }   obj.form.Text.value = rot13 } </script> <form> <center>Encode / Decode ROT13 (cipher) <HR noshade width="80%" size="1"> <textarea name="Text" rows=8 cols=40 wrap=soft></textarea><br><br> <input type=button value="Encode / Decode" class="button" onClick="rot_13(this)"> <input type="reset" name="clear" class="button" value="Reset"/> </form> </center> </body> </html>

By Blogger Biasa - February 28, 2010 - 1 Comment

1 comments:

Balas

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