Entries Tagged "history of cryptography"

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Mary Queen of Scots Letters Decrypted

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, they quickly realised the letters were in French. Many verb and adjectival forms being feminine, regular mention of captivity, and recurring names—such as Walsingham—all put them on the trail of Mary. Sir Francis Walsingham was Queen Elizabeth’s spymaster.

The code was a simple replacement system in which symbols stand either for letters, or for common words and names. But it would still have taken centuries to crunch all the possibilities, so the team used an algorithm that homed in on likely solutions.

Academic paper.

EDITED TO ADD (2/13): More news.

Posted on February 9, 2023 at 7:15 AM • View Comments

Charles V of Spain Secret Code Cracked

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 Arabic.

In another obstacle, he used meaningless symbols to mislead any adversary trying to decipher the message.

The breakthrough came in June when Pierrot managed to make out a phrase in the letter, and the team then cracked the code with the help of Camille Desenclos, a historian. “It was painstaking and long work but there was really a breakthrough that happened in one day, where all of a sudden we had the right hypothesis,” she said.

Posted on November 29, 2022 at 7:19 AM • View Comments

Gus Simmons’s Memoir

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 rural West Virginia. I’m in the middle of reading it, and it’s fascinating.

More blog posts.

Posted on March 25, 2022 at 6:14 AM • View Comments

Military Cryptanalytics, Part III

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 Wayne Griswold Barker’s Agean Park Press. I own them in hardcover.

Like Parts I and II, Part III is primarily concerned with pre-computer ciphers. At this point, the document only has historical interest. If there is any lesson for today, it’s that modern cryptanalysis is possible primarily because people make mistakes

The monograph took a while to become public. The cover page says that the initial FOIA request was made in July 2012: eight and a half years ago.

And there’s more books to come. Page 1 starts off:

This text constitutes the third of six basic texts on the science of cryptanalytics. The first two texts together have covered most of the necessary fundamentals of cryptanalytics; this and the remaining three texts will be devoted to more specialized and more advanced aspects of the science.

Presumably, volumes IV, V, and VI are still hidden inside the classified libraries of the NSA.

And from page ii:

Chapters IV-XI are revisions of seven of my monographs in the NSA Technical Literature Series, viz: Monograph No. 19, “The Cryptanalysis of Ciphertext and Plaintext Autokey Systems”; Monograph No. 20, “The Analysis of Systems Employing Long or Continuous Keys”; Monograph No. 21, “The Analysis of Cylindrical Cipher Devices and Strip Cipher Systems”; Monograph No. 22, “The Analysis of Systems Employing Geared Disk Cryptomechanisms”; Monograph No.23, “Fundamentals of Key Analysis”; Monograph No. 15, “An Introduction to Teleprinter Key Analysis”; and Monograph No. 18, “Ars Conjectandi: The Fundamentals of Cryptodiagnosis.”

This points to a whole series of still-classified monographs whose titles we do not even know.

EDITED TO ADD: I have been informed by a reliable source that Parts 4 through 6 were never completed. There may be fragments and notes, but no finished works.

Posted on January 4, 2021 at 2:34 PM • View Comments

Enigma Machine Recovered from the Baltic Sea

Neat story:

German divers searching the Baltic Sea for discarded fishing nets have stumbled upon a rare Enigma cipher machine used by the Nazi military during World War Two which they believe was thrown overboard from a scuttled submarine.

Thinking they had discovered a typewriter entangled in a net on the seabed of Gelting Bay, underwater archaeologist Florian Huber quickly realised the historical significance of the find.

EDITED TO ADD: Slashdot thread.

Posted on December 4, 2020 at 9:18 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.