I don’t remember how I found this file, I think it was suggested to me by someone on Facebook (in which case, thanks!, and I apologize for not remembering your name).
Jim Sauerberg was a professor of math at St. Mary’s College of California, and on one website was listed as the Professor and Chair of the Department of Mathematics and Computer Science there. I’m not finding anything more recent than roughly 2019.
Cryptology: An Historical Introduction – DRAFT, by Jim Sauerberg (2013) pp. 257
As indicated by the title, this is a draft version of a textbook that is currently available on docplayer.net. I’ve got no idea whether it was ever cleaned up and released publicly. Jim isn’t listed on Amazon.com, and maybe the title was changed at some point because I can’t find it listed anywhere else.
As a draft copy, Cryptology isn’t that bad. There are a number of typos, and a couple missing illustrations. I think the most glaring error is that the Beaufort table and examples are actually for Vigenere. Otherwise, this is a pretty good introduction to “classical cipher systems,” which builds up into a discussion of modern public key encryption. If you have seen The Manga Guide to Cryptography, or Sweigart’s Cracking Codes with Python, then you’ll have a pretty good idea of what to expect here (minus the manga and the Python programming stuff).
Probably the strongest part of Cryptology is the inclusion of small infobites of background on various historical figures (such as Porta, Trithemius, Beaufort and Gronsfeld). Jim has information on Beaufort and Gronsfeld I haven’t seen elsewhere to date. However, his bibliography for the classical references (pre-public key) duplicates a lot of what I’ve reviewed/summarized for the Black Chamber already, so there’s nothing much new in terms of book references.
This was a proposed textbook, so there are a lot of practice exercises and self-checks, if that’s something you’re after. A lot of the quotes for the practices come from well-known texts, like Parker Hitt’s Manual, David Kahn’s The Codebreakers and General Marcel Givierge’s Course in Cryptography. Jim refers to simple substitution ciphers with word breaks as “Aristocrats,” but I haven’t seen anything in the text explaining where that term came from, or any mentions of the American Cryptogram Association (ACA).
On the whole the first half of the book is a decent introduction to classical cryptographic systems, including Caesar shift, Aristocrats, Vigenere (ignoring the problems of the Beaufort and Variant tables), and some of the earlier digraphic systems (leading into Playfair). There’s a good discussion of Friedman’s Index of Coincidence and Sinkov’s related Measurement of Roughness as applied to finding Vigenere keywidths. I hadn’t seen anything on MoR before, or on Sukhotil’s method for identifying the vowels in short simple subs. I need to look at those more closely for the TKinter autosolvers.
TOC
1 Caesar Ciphers
2 Cryptologic Terms
3 The Introduction of Numbers
4 The Euclidean Algorithm
5 Monoalphabetic Ciphers
6 Decrypting Monoalphabetic Ciphers
7 Vigenere Ciphers
8 Polyalphabetic Ciphers
9 Digraphic Ciphers
10 Transposition Ciphers
11 Knapsack Ciphers
12 RSA
Specific comments and highlights by page.
p. 79 – A list of the top 100 English words (I may have to add part of this to the n-gram counter).
p. 97 – Description of B. V. Sukhotin’s method, which is based on analyzing the frequencies of letter pairings, since vowels tend to pair up well with most of the consonants.
p. 116 – Vigenere table presented as the Beaufort table.
p. 120 – The Kasiski test is described here, for finding the widths of Vigenere-family keys. No mention of Charles Babbage describing this method earlier.
p. 128 – Practice cipher based on text from Charles Babbage’s Passages from the Life of a Philosopher. Easily broken with a wordlist attack.
p. 139 – Discussion of Sinkov’s Measure of Roughness, which is related to the Index of Coincidence, but can help find Vigenere-family key widths.
p. 143 – Showing “Friedman’s test for monoalphabetic versus polyalphabetic messages.” Can also be used for suggesting keywidths.
p. 153 – Venona Project misspelled as “Verona Project.”
p. 188 – Footnote 23. Describes Helen Fouche-Gaine’s Slidefair cipher, which uses a St. Cyr slide (regular Caesar slide) combined with the Playfair rules.
p. 189/190 – The transposition chapter may be the weakest part of the book as far as traditional cipher systems are concerned. Jim describes Route transpositions as being another name for Railfence; and Geometric transpositions as being Routes. The section on Columnar transpositions doesn’t get into the distinction between Complete and Incomplete rectangles, and there’s no mention of Friedman’s vowel frequency attack for getting rectangle widths, or of hatting for breaking Incomplete ciphers.
p. 219 – The chapter on Knapsack Ciphers is short compared to the other chapters, and the conclusion at the end is that the concept of Knapsack ciphers is flawed and they can be relatively easily broken. Effectively, the idea is to employ the mathematical knapsack problem (you have a dragon with a horde of gold, each bar of known weight – how do you decide which and how many of the bars to take if none of the totals adds up to the top weight your knapsack can carry?) The cipher approach is to use multipliers for getting substitution values into an alphabet, in a way that’s kind of similar to the Fixed Distance transposition system. This is a public key encryption system, where the private key is kept secret.
p. 231 – We get to the final chapter, on RSA. I covered RSA in the Manga Guide to Cryptography review, and in the Sweigart review. The only thing that may be new here is the short part on digital signatures.
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Overall, as a draft, Cryptology: An Historical Introduction is best for beginners that want to see a lot of historical references and cipher system descriptions all in one place, and don’t mind the errors. I’d like to see the finished product, if there is one. As for me, the sections on the Friedman tests and the Sinkov Measurement of Roughness might be useful for the auto-solvers when I get to Vigenere systems. Recommended.
The Black Chamber 