Solving the “Rotation” puzzle in stages

Introduction A few months ago (in June last year), I wrote a simple puzzle named “Rotation”  (play here) that involves rearranging a grid of jumbled-up numbers in order by rotating groups of numbers about. The player clicks on the cyan colored buttons in order to rotate the group of numbers immediately adjacent to it clockwise. In the…

Frequency Analysis Attack – Breaking the Substitution Cipher

The Substitution Cipher Perhaps the oldest and one of the simplest method of encrypting a message is to use the substitution cipher. What this cipher does is, as its name suggests, to simply substitute each character in the message with the character it is mapped to. In this article, we will examine substitution ciphers specifically…

P2P File Transfer over TCP

File transfers usually take place via an intermediate server – Your files get uploaded to the intermediate server, and others download from the intermediate server instead of from you. On the other hand, in another perhaps less well-known class of file transfers, Peer-To-Peer (P2P) file transfers, the files get sent directly from you to the…

Monitoring Home Web Traffic With A Local DNS Proxy

What happens when you key in some domain name, say “banana.com”, into your laptop’s web browser and hit the enter button? Does your web browser automatically and magically connect to this domain, “banana.com”? How exactly does your web browser know where “banana.com” is even located at? To answer all these questions, we must first understand…