The desire for relative privacy in correspondence has given rise to a variety of techniques for safeguarding messages from the eager eyes of unauthorized peepers and curious officials. Over four thousand years ago the Babylonians already used clay envelopes to seal their clay “letters.” The Romans secured their diptych wax tablets with leather string. In the Middle Ages and Renaissance great wax seals became popular. Since 1840 when the modern envelope was invented, only simple gum and legal sanctions have stood between epistolary spies and their targets. Yet the unfortunate point must be made that all methods of sealing letters have proven equally unsuccessful.
Nor have codes, ciphers, or secret inks managed to foil the ingenuity of professional sleuths. From simple mirror writing to elaborate replacement schemes and polyalphabetic ciphers, all codes have met their master analysts. But the need for secrecy, especially in politics and warfare, and the need to know what the “other side” knows grows more important as communication networks continue to expand.
The history of cryptology (the study of codes and secret writings) is thoroughly intertwined with the history of postal systems, representing the dark underside of the development of human language and communication.
The very first reference to writing in Western literature already hints at the inevitable connection. In Book 6 of the
Homer tells the story of Bellerophon, who is sent by King Proteus to the King of Lycia. Proteus supplies Bellerophon with credentials, “murderous symbols, which he inscribed in a folding tablet.” Presumably the message said something like, “Treat this man as well as you did Glaukos.” (In Shakespeare’s time, “well” also meant “dead”—hence the dark irony of the play
All’s Well That Ends Well
The Roman inspectors of the relay stations along the great postal roads, who also acted as spies and agents for the emperor, were called
, from which we get our word for eager prying or meddling.
With the increase in diplomatic traffic came a greater need for codemakers and codebreakers. In the early Renaissance ancient codes were rediscovered, dusted off for use, and new code systems were invented. Kings, Popes and city states instituted ‘Black Chambers,’ where clerks enand decoded messages, and cryptologists tried to crack the codes of intercepted dispatches. The Black Chamber in Vienna was as notorious as it was efficient, combing every piece of official mail daily in less than three hours. Nearly every document, every letter, contained some portion in code: what Count So-and-so whispered to the Duchess X, what secret alliances were struck in back rooms. Every diplomat (they were known as “honorable spies”) had his personal code book.
By the beginning of the l9th century public outcry against censorship had led to the abolishing of the Black Chambers. The invention of the telegraph in 1843 opened new vistas for diplomatic and military communication, requiring more sophisticated coding systems, since telegraph lines can be tapped, radio waves intercepted, telephone conversations overheard. It also marked the end of secret writing and ciphers in letters. But the job of deciphering telegrams and radio messages still requires working with the written text.
(Encoding messages, and deciphering them, might be good exercises for students. Cryptanalysis demands investigating language—word, letter, and letter combination frequencies—and can be a way for students to see language as a symbolic system that can be manipulated.)