Really interesting analysis of the American M-209 encryption device and its security. [...]

The NSA’s “ National Cryptographic School Television Catalogue ” from 1991 lists about 600 COMSEC and SIGINT training videos. There are a bunch explaining the operations of various cryptographic equipment, and a few code words I have never heard of before. [...]

Really interesting article on the ancient-manuscript scholars who are applying their techniques to the Voynich Manuscript. No one has been able to understand the writing yet, but there are some new understandings: Davis presented her findings at the medieval-studies conference and published them in 2020 in the journal Manuscript …

Interesting paper about a German cryptanalysis machine that helped break the US M-209 mechanical ciphering machine. The paper contains a good description of how the M-209 works. [...]

The Polish Embassy has posted a series of short interview segments with Marian Rejewski, the first person to crack the Enigma. Details from his biography. [...]

During the Cold War, the US Navy tried to make a secret code out of whale song. The basic plan was to develop coded messages from recordings of whales, dolphins, sea lions, and seals. The submarine would broadcast the noises and a computer—the Combo Signal Recognizer (CSR)—would …

Through a 2010 FOIA request (yes, it took that long), we have copies of the NSA’s KRYPTOS Society Newsletter, “ Tales of the Krypt,” from 1994 to 2003. There are many interesting things in the 800 pages of newsletter. There are many redactions. And a 1994 review of Applied …

David Kahn has died. His groundbreaking book, The Codebreakers was the first serious book I read about codebreaking, and one of the primary reasons I entered this field. He will be missed. [...]

GCHQ has released new images of the WWII Colossus code-breaking computer, celebrating the machine’s eightieth anniversary (birthday?). News article. [...]

Looks like fun. Details here. [...]

This is a neat piece of historical research. The team of computer scientist George Lasry, pianist Norbert Biermann and astrophysicist Satoshi Tomokiyo—all keen cryptographers—initially thought the batch of encoded documents related to Italy, because that was how they were filed at the Bibliothèque Nationale de France. However …

Diplomatic code cracked after 500 years: In painstaking work backed by computers, Pierrot found “distinct families” of about 120 symbols used by Charles V. “Whole words are encrypted with a single symbol” and the emperor replaced vowels coming after consonants with marks, she said, an inspiration probably coming from …

Gus Simmons is an early pioneer in cryptography and computer security. I know him best for his work on authentication and covert channels, specifically as related to nuclear treaty verification. His work is cited extensively in Applied Cryptography. He has written a memoir of growing up dirt-poor in 1930s …

Jon D. Paul has written the fascinating story of the HX-63, a super-complicated electromechanical rotor cipher machine made by Crypto AG. [...]

Late last year, the NSA declassified and released a redacted version of Lambros D. Callimahos’s Military Cryptanalytics, Part III. We just got most of the index. It’s hard to believe that there are any real secrets left in this 44-year-old volume. [...]

This is a newly unclassified NSA history of its reaction to academic cryptography in the 1970s: “ NSA Comes Out of the Closet: The Debate over Public Cryptography in the Inman Era,” Cryptographic Quarterly, Spring 1996, author still classified. [...]

This is a newly unclassified NSA history of its reaction to academic cryptography in the 1970s: “ New Comes Out of the Closet: The Debate over Public Cryptography in the Inman Era,” Cryptographic Quarterly, Spring 1996, author still classified. [...]

Nice video of a talk by Chris Shore on the history of Colossus. [...]

The NSA has just declassified and released a redacted version of Military Cryptanalytics, Part III, by Lambros D. Callimahos, October 1977. Parts I and II, by Lambros D. Callimahos and William F. Friedman, were released decades ago — I believe repeatedly, in increasingly unredacted form — and published by the late …