Page:Friedman Lectures on Cryptology.pdf/6

Rh Lecture I

The objective of this series of lectures is to create an awareness of the background, development, and manner of employment of a science that is the basis of a vital military offensive and defensive weapon known as CRYPTOLOGY, a word that comes from the Greek kryptos, meaning secret or hidden, plus logos, meaning knowledge or learning. Cryptology will be specifically defined a little later; at the moment, however, I'm sure you know that it has to do with secret communications.

Let me say at the outset of these lectures that I may from time to time touch upon matters which are perhaps essentially peripheral or even irrelevant to the main issues, and if a defense is needed for such occasional browsing along the byways of the subject, it will be that long preoccupation with any field of knowledge begets a curiosity the satisfaction of which is what distinguishes the dedicated professional from the person who merely works just to gain a livelihood in whatever field he happens to find himself a job. That's not much fun, I'm afraid. By the way, a British writer, James Agate, defines a professional as the man who can do his job even when he doesn't feel like doing it; an amateur, as a man who can't do his job even when he does feel like doing it. This is pretty tough on the gifted amateur and I for one won't go all the way with Agate's definition. There are plenty of instances where gifted amateurs have done and discovered things to the chagrin and red-facedness of the professionals.

Coming back now to the main thoroughfare after the foregoing brief jaunt along a byway, I may well begin by telling you that the science of cryptology has not always been regarded as a vital military offensive and defensive weapon, or even as a weapon in the first place. Here I am reminded of a story in a very old book on cryptography. The story is probably apocryphal, but it's a bit amusing, and I give it for what it's worth.

It seems that about two thousand years ago there lived a Persian queen named Semiramis, who took an active interest in cryptology. She was in some respects an extraordinarily unpleasant woman, and we learn without surprise that she met with an untimely death. She left behind her instructions that her earthly remains were to be placed in a golden sarcophagus within an imposing mausoleum, on the outside of which, on its front stone wall, there was to be graven a message, saying:

Stay, weary traveller! If thou art footsore, hungry, or in need of money&mdash; Unlock the riddle of the cipher graven below, And thou wilt be led to riches beyond all dreams of avarice!

Below this curious inscription was a cryptogram, a jumble of letters without meaning or even pronounceability. For several hundred years the possibility of sudden wealth served as a lure to many experts who tried very hard to decipher the cryptogram. They were all without success, until one day there appeared on the scene a long-haired, bewhiskered, and bespectacled savant who, after working at the project for a considerable length of time, solved the cipher, which gave him detailed instructions for finding a secret entry into the tomb. When he got inside, he found an instruction to open the sarcophagus, but he had to solve several more cryptograms the last one of which may have involved finding the correct combination to a 5-tumbler combination lock&mdash;who knows? Well, he solved that one too, after a lot of work, and this enabled him to open the sarcophagus, inside which he found a box. In the box was a message, this time in plain language, and this is what it said: Rh