Like hell they don't, when the "gentlemen" involved are the governments of countries--
But they didn't use to, or not much, for the very simple reason that they were rarely able to get at one another's mail. Letters in a courier's pouch, slips of paper carried by a pigeon: needles in a haystack and worse, they're extraordinarily difficult to intercept without revealing that they have been intercepted. Technology began to change that. Wired telegraphy is difficult (but not impossible) to tap with 19th-Century technology but it is inherently insecure; operators can be bribed, trash rifled through for carelessly discarded messages, sharp eyes and ears in the office can read messages from the wire as easily as reading over someone's shoulder.... And then came radio, nearly as open as shouting from the rooftops: suddenly, the "gentlemen" might as well be throwing their letters through each other's transoms!*
They were not, however, writing them in plain text. Codes and ciphers were the thing, and so was decoding them, or trying to.
In the First World War, the United States barely had a cryptological effort. The military did what they could, eventually resulting in Herbert O.Yardley's "Black Chamber," MI-8, but well before he was up and running, they had to turn to civilian help. (I will note Yardley was a Hoosier. This may be significant.)
Enter Riverbank Laboratories (still around today: same location, but they pursued another of the lab's interests. And the original building would hardly be out of place in a spy film!). Enter eccentric millionaire George Fabyan, his eccentric (but by no means unshared) belief that Francis Bacon was the real author of Shakespeare's works, and the eccentric theory that this information was somehow encrypted in the earliest printed versions of Shakespeare. And to decode that, a millionaire needs a staff of cryptologists working in his private labs on his private estate.
It's a story right out of a-- I was going to write, "pulp magazine," but it's too wild for that. It's straight out a dime novel. Picture an estate sprawling along and across the Fox River near Geneva, Illinois, complete with a home remodeled by Frank Lloyd Wright, a Dutch windmill grinding grain, a private zoo, a Japanese garden, a Roman swimming pool on a island in the river; picture over a hundred people working on various projects that had struck Fabyan's fancy, from acoustical levitation to improved grains, from trench design to cast-concrete art. Picture it not in a book or film, but in real life.
Bacon having written Shakespeare was a bust; the "biliteral code" theorist on Fabyan's payroll was, it seems, self-deceived. But the cryptology effort had attracted other talented people and among them were geneticist William F. Friedman and Elizebeth (yes, with three e's) Smith, the latter of Huntington, Indiana.† When WW I --The Great War -- began roaring through Europe, the government turned to Colonel Fabyan. Fabyan turned to his staff; specifically, to Smith and Friedman.
Smith was the scholar of language, Friedman the analyst -- but between them, technique and skills developed rapidly; before the war was over, they had not only decoded huge numbers of messages but written a series of booklets that still comprise an introductory course to cryptanalysis, a science they named and were instrumental in developing.
As inevitably as in, well, a dime novel, the two fell in love and married-- And after the Great War ended, they fled Riverbank: Fabyan was still an eccentric millionaire, with all that entails, and had been intercepting Washington's job offers to the two of them for quite some time.
The two of them went from strength to strength and adventure to adventure after that -- helping to catch rumrunners, aiding in the efforts to crack Japanese codes, and so on. I'm in the midst of reading a fascinating biography of Elizebeth Smith Friedman, and it's still the stuff of spy novels -- only better. It happened; she and William really did these things.
* I'm not going to explain what a "transom" is. I have lived in a building that had transoms, and they can be a very great relief in summer's heat and winter's stuffiness, a lost grace note. Unless you have neighbors who frequently cook cabbage.
† I keep running into Hoosier cryptologists and spies. Are we a state of geeky romantics? And is it related to why are there so many Hoosier comedians, as well?
2 months ago