AI Used to Decrypt Medieval Ciphers - Schneier on Security

Researchers are using machine learning algorithms to decrypt historical pencil-and-paper ciphers.

Medieval Encrypted Letter Decoded - Schneier on Security

Sent by a Spanish diplomat. Apparently people have been working on it since it was rediscovered in 1860.

Inventors of Quantum Cryptography Win Turing Award - Schneier on Security

Charles Bennett and Gilles Brassard have won the 2026 Turing Award for inventing quantum cryptography. I am incredibly pleased to see them get this recognition. I have always thought the technology to be fantastic, even though I think it’s largely unnecessary. I wrote up my thoughts back in 2008, in an essay titled “Quantum Cryptography: As Awesome As It Is Pointless.” Back then, I wrote: While I like the science of quantum cryptography—my undergraduate degree was in physics—I don’t see any commercial value in it. I don’t believe it solves any security problem that needs solving. I don’t believe that it’s worth paying for, and I can’t imagine anyone but a few technophiles buying and deploying it. Systems that use it don’t magically become unbreakable, because the quantum part doesn’t address the weak points of the system...

Book Review: The Business of Secrets - Schneier on Security

The Business of Secrets: Adventures in Selling Encryption Around the World by Fred Kinch (May 24, 2024) From the vantage point of today, it’s surreal reading about the commercial cryptography business in the 1970s. Nobody knew anything. The manufacturers didn’t know whether the cryptography they sold was any good. The customers didn’t know whether the crypto they bought was any good. Everyone pretended to know, thought they knew, or knew better than to even try to know. The Business of Secrets is the self-published memoirs of Fred Kinch. He was founder and vice president of—mostly sales—at a US cryptographic hardware company called Datotek, from company’s founding in 1969 until 1982. It’s mostly a disjointed collection of stories about the difficulties of selling to governments worldwide, along with descriptions of the highs and (mostly) lows of foreign airlines, foreign hotels, and foreign travel in general. But it’s also about encryption...

1965 Cryptanalysis Training Workbook Released by the NSA - Schneier on Security

In the early 1960s, National Security Agency cryptanalyst and cryptanalysis instructor Lambros D. Callimahos coined the term “Stethoscope” to describe a diagnostic computer program used to unravel the internal structure of pre-computer ciphertexts. The term appears in the newly declassified September 1965 document Cryptanalytic Diagnosis with the Aid of a Computer, which compiled 147 listings from this tool for Callimahos’s course, CA-400: NSA Intensive Study Program in General Cryptanalysis. The listings in the report are printouts from the Stethoscope program, run on the NSA’s Bogart computer, showing statistical and structural data extracted from encrypted messages, but the encrypted messages themselves are not included. They were used in NSA training programs to teach analysts how to interpret ciphertext behavior without seeing the original message...

Jim Sanborn Is Auctioning Off the Solution to Part Four of the Kryptos Sculpture - Schneier on Security

Well, this is interesting: The auction, which will include other items related to cryptology, will be held Nov. 20. RR Auction, the company arranging the sale, estimates a winning bid between $300,000 and $500,000. Along with the original handwritten plain text of K4 and other papers related to the coding, Mr. Sanborn will also be providing a 12-by-18-inch copper plate that has three lines of alphabetic characters cut through with a jigsaw, which he calls “my proof-of-concept piece” and which he kept on a table for inspiration during the two years he and helpers hand-cut the letters for the project. The process was grueling, exacting and nerve wracking. “You could not make any mistake with 1,800 letters,” he said. “It could not be repaired.”...

SIGINT During World War II - Schneier on Security

The NSA and GCHQ have jointly published a history of World War II SIGINT: “Secret Messengers: Disseminating SIGINT in the Second World War.” This is the story of the British SLUs (Special Liaison Units) and the American SSOs (Special Security Officers).

The Combined Cipher Machine - Schneier on Security

Interesting article—with photos!—of the US/UK “Combined Cipher Machine” from WWII.

Long Analysis of the M-209 - Schneier on Security

List of Old NSA Training Videos - Schneier on Security