Meet a Cryptographer

            Seven O'clock in the morning is really not a good time to interview someone, I have decided. It took me several minutes to punch in the numbers on my phone with my sleepy fingers. However, because of the different time zone, I was only just able to catch my interviewee before he left work. When I finally got through to Ralph Kastmann, his timid, definitely accented, Swiss voice answered the phone. "Ralph Kastermann of Media Crypt"

            I am grateful that I got a person to interview at all. First, I tried contacting many different people, before I contacted the person who I wrote a letter to- Ralph Kastmann. Ralph Kastmann is a Swiss cryptographer who is currently working for Media Crypt, a company that develops new ways to encrypt media. Under this company, he has been involved in two major projects. The first one he was involved in was one that most big countries in the world participated in (England, the United States of America, Japan, etc.), and it was a project where all of these countries pooled together knowledge about cryptography to allow more secure algorithms to be invented. The recent project that he was part of was a project called "FOX" and its aim was to create a fast, strong, and desirable encryption algorithm for encrypting data.

            When he was young, Ralph Kastmann was never interested in cryptography, his interest developed later in life. "I was interested in physics and math, when I was first introduced to cryptography," he recalls. At the time that PCs and the Internet became usable to the general public, Ralph became intrigued by cryptography, but still just as a job opportunity. This is when he joined the company that he currently works for, Media Crypt. Before joining this company, he was mildly interested in cryptography, but after he joined, he was hooked.

            Most of the types of algorithms that Ralph helps make and troubleshoot are symmetrical ones. The idea behind symmetrical algorithms is that both the sender and the receiver know one "key" or sequence of letters and/or numbers that decrypts the information. This is probably the most secure type of algorithm, but it requires a secure channel in the first place so that the sender and receiver have the same key. Quantum cryptography is a new type of cryptography having to do with providing that safe channel. Here is a brief description of Quantum cryptography: the sender sends a signal of polarized photons, either diagonal (2 possibilities) or up and down or sideways (another 2), the exact selection that the sender chooses to polarize the photon is done at random. Using 1 of two detectors (up/down and sideways, or diagonal) with the exact detector chosen at random, the receiver is able to sense the polarization of the photons, and is then able to derive a bit sequence (a line of 0s and 1s) from these detections, and generate a code, some of the 0s and 1s being false, because the detector used was not the right one. Then, using a public channel (i.e. email or phone line), the receiver tells what detector filter he used for each incoming photon (not the bit sequence), and the sender tells the receiver which predictions of which detector to use he/she got right. The most fascinating part about quantum cryptography, is that if someone listens in on a "conversation" (the sending of photons), then the laws of quantum mechanics dictate that the polarization of the photons would be changed if the eavesdropper used the wrong detection filter, and the change would be detectable by the receiver when he/she converses with the sender.

            This exciting new field of quantum cryptography is one of the things that Ralph Kastmann is currently working on. From him, I learnt many of the recent events in cryptography, and also about what a cryptographer's job is. I also was able to get a glimpse of the view of modern cryptography from someone who is experienced and knowledgeable in this field. It was definitely worth getting up at 7 am!