Quotes from David Kahn

Do it because it needs to be done. Do it to make your world better…just a little at a time.

I said he's the best at what he does. Not at what I do.

watch out for schools that promise your kids will "experience success." I'm teaching Plato's Dialogues these days, and I noticed that Socrates never let his students experience success. Socrates won the argument every time.

Much of the history of cryptology of this time is a patchwork, a crazy quilt of unrelated items, sprouting, flourishing, withering. Only toward the Western Renaissance does the accreting knowledge begin to build up a momentum. The story of cryptology during these years is, in other words, exactly the story of mankind.

the use of atbash in the Bible sensitized the monks and scribes of the Middle Ages to the idea of letter substitution. And from them flowed the modern use of ciphers—as distinct from codes—as a means of secret communication.

The multiple human needs and desires that demand privacy among two or more people in the midst of social life must inevitably lead to cryptology wherever men thrive and wherever they write. Cultural diffusion seems a less likely explanation for its occurrence in so many areas, many of them distant and isolated.

I can't say I ever remember getting less than a whole child in my 29 years here. They come in whole and I teach 'em that way.

He was also talented in other directions: he played the violin well and was an accomplished artist, exhibiting at, among others, the Chicago Art Institute.

If two direction-finders take bearings like that on a signal and a control center draws the lines of direction on a map, the point at which they cross marks the position of the transmitter.

since military operations are usually accompanied by an increase in communications, traffic analysis can infer the imminence of such operations by watching the volume of traffic. When combined with direction-finding, it can often approximate the where and when of a planned movement.

Plaintext a might be represented in a long message by all 26 letters. Conversely, any given ciphertext letter might stand for any one of 26 plaintext letters.

The more a cipher deviates from the simple form in which one ciphertext letter invariably replaces the same plaintext letter, the harder it is to break.

Its coding wheels, stepping a space—or two, or three, or four—after every letter or so, did not return to their original positions to re-create the same series of paths, and hence the same sequence of substitutes, until hundreds of thousands of letters had been enciphered.

The task of the cryptanalysts consisted primarily of reconstructing the wiring and switches of the coding wheels—a task made more burdensome by the daily change of plugboard connections.

This kind of work, particularly in the early stages of a difficult cryptanalysis, is perhaps the most excruciating, exasperating, agonizing mental process known to man.

Friedman was (and is) the world's greatest cryptologist.

He served as a cryptanalyst with the American Expeditionary Forces in World War I, and returned to River-bank to write an 87-page tract that revolutionized cryptanalysis by introducing statistical methods for the first time.

one of the essential elements of cryptography: a deliberate transformation of the writing.

For written messages, the Chinese would often write on exceedingly thin silk or paper, which they rolled into a ball and covered with wax. The messenger hid the wax ball, or "la wan," somewhere about his person, or in his rectum, or he sometimes swallowed it.

between 321 and 300 B.C., recommended that ambassadors use cryptanalysis to obtain intelligence: "If there is no possibility of carrying on any such conversation (conversation with the people regarding their loyalty), he [the envoy] may try to gather such information by observing the talk of beggars, intoxicated and insane persons, or of persons babbling in sleep, or by observing the signs made in places of pilgrimage and temples, or by deciphering paintings or secret writings.

His method resembles George Bernard Shaw's way of using the /f/ sound of GH in "tough," the /i/ sound of o in "women," and the /sh/ sound of TI in "nation" to write fish as GHOTI. The scribe also

Gorgo, who may be considered the first woman cryptanalyst

they employed a device called the "skytale," the earliest apparatus used in crypto-logy

The world owes its first instructional text on communications security to the Greeks. It appeared as an entire chapter in one of the earliest works on military science, On the Defense of Fortified Places, by Aeneas the Tactician.