Computing

Vigenère Cipher And Breaking it

It was originally thought to be unbreakable. You use a key such as PASSWORD.  Each Letter in your message is encoded by placing PASSWORDPASSWORDPASSWORD THISISATESTOFTHECODE Each letter is encoded by using choosing the corresponding row from the key letter above your message letter.  The obvious failing is that after a bit Read more…

By Fudgy McFarlen, ago
Information-Theory

What is Entropy?

There are many mathematical definitions of entropy.  The mental picture I find most useful is to imagine the following:   you are put in a room and your job is to label everything in the room with a sharpy indelible marker and masking tape.   You are asked to label everything in Read more…

By Fudgy McFarlen, ago