Monday, February 9, 2015

Cryptography: The Science of Minutia

I find that surprisingly, in Modern Physics, I'm often inspired to learn about Computer Science. In our nanotechnology unit, one person shared a project about a tamper-proof alternative to RSA encryption using polarized light. The method made a lot of sense to me, and I thought encryption was fascinating, so I decided to learn a bit more about encryption. I've been doing it through this Udacity Course, and so far, my main takeaway has been that although ciphers may seem very secure, even the slightest weakness can be exploited and used to crack a cipher.

A good example of this would be the Lorenz Cipher. This machine was made to use the "one-time-pad" method of encryption, where a unique key is created every time to cipher text.

Lorenz Cipher Diagram

A character would be encoded as 5 bits, then each would be xor'd with either a 1 or a 0, depending on the configuration of the dials K1 to K5. After that, the Lorenz Cipher would check the status of the M1 and M5 dials, and xor them together. If the result was 1, then all the S1 dials would turn. There were two large flaws in this cipher. First, because the messages were transmitted in German, the original message bits were more likely to have certain values. Secondly, because the S dials all rotated at the same time, they were more likely to be 1's than 0's. These small mechanical flaws in the machine turned what seemed to be a foolproof, random cipher into something that the Allies of WWI were able to crack after significant effort. It just shows that attackers will pour inordinate amounts of effort into breaking ciphers, and the smallest mathematical holes can lead to wars being won or lost. I plan to finish this Udacity course, and gain a better grounding in Cryptography before going to college.