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Lecture #9:  Guest lecture by J. Reeds

I invited a guest lecturer, Jim Reeds of AT&T, who does crypto in the "real world". Below is an advertisement for his talk. Several graduate students attended. I also invited students from last semester's course to attend. The date of this talk was February 16, 2000. His abstract:

Real cryptanalysis
I distinguish between "real" cryptanalysis, in which one is actually trying to break real code messages sent by real people, and "practice" cryptanalysis, in which one is assessing algorithm strength, developing new analysis methods, practicing, doing homework, solving challenge puzzles, etc. Although the latter is every bit as intellectually challenging as the former, I think the former is by far the sexier. Alas, it is usually practiced by intelligence agencies, criminals, industrial espionage agents, detectives, etc, and is thus rarely described in the open literature until long after the fact. I have been lucky in having done some "real" cryptanalysis that I can talk about, and lucky again because the examples are not too technical to explain here today.
Dr. Reeds discussed two topics. One was "shoulder surfing", where people illegally copy and use code numbers for long-distance service. He has been called as a expert witness by police to decrypt such numbers when given them encrypted via some hand system.

He also gave a more extended discussion of his work in decrypting a book of Trithemius. The following is quoted from one of his web pages:

Book 3 of Trithemius's Steganographia (written ca. 1500) contains hidden cipher messages within what is ostensibly a magic work. After almost 500 years these ciphers have been detected and solved. (Since 1606 it was known that similar ciphers were present in Books 1 and 2.) This has implications not only for the history of cryptography but also for the history of 16th century magic. Trithemius has been considered one of the main figures in the rise of the occult movement in the 1500's, but it now turns out that the evidence is less clear.

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