Entries Tagged "NSA"

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1965 Cryptanalysis Training Workbook Released by the NSA

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.

The listings include elements such as frequency tables, index of coincidence, periodicity tests, bigram/trigram analysis, and columnar and transposition clues. The idea is to give the analyst some clues as to what language is being encoded, what type of cipher system is used, and potential ways to reconstruct plaintext within it.

Bogart was a special-purpose electronic computer tailored specifically for cryptanalytic tasks, such as statistical analysis of cipher texts, pattern recognition, and diagnostic testing, but not decryption per se.

Listings like these were revolutionary. Before computers, cryptanalysts did this type of work manually, painstakingly counting letters and testing hypotheses. Stethoscope automated the grunt work, allowing analysts to focus on interpretation, and cryptanalytical strategy.

These listings were part of the Intensive Study Program in General Cryptanalysis at NSA. Students were trained to interpret listings without seeing the original ciphertext, a method that sharpened their analytical intuitive skills.

Also mentioned in the report is Rob Roy, another NSA diagnostic tool focused on different cryptanalytic tasks, but also producing frequency counts, coincidence indices, and periodicity tests. NSA had a tradition of giving codebreaking tools colorful names—for example, DUENNA, SUPERSCRITCHER, MADAME X, HARVEST, and COPPERHEAD.

Posted on September 2, 2025 at 7:08 AM • View Comments

“Encryption Backdoors and the Fourth Amendment”

Law journal article that looks at the Dual_EC_PRNG backdoor from a US constitutional perspective:

Abstract: The National Security Agency (NSA) reportedly paid and pressured technology companies to trick their customers into using vulnerable encryption products. This Article examines whether any of three theories removed the Fourth Amendment’s requirement that this be reasonable. The first is that a challenge to the encryption backdoor might fail for want of a search or seizure. The Article rejects this both because the Amendment reaches some vulnerabilities apart from the searches and seizures they enable and because the creation of this vulnerability was itself a search or seizure. The second is that the role of the technology companies might have brought this backdoor within the private-search doctrine. The Article criticizes the doctrine­ particularly its origins in Burdeau v. McDowell­and argues that if it ever should apply, it should not here. The last is that the customers might have waived their Fourth Amendment rights under the third-party doctrine. The Article rejects this both because the customers were not on notice of the backdoor and because historical understandings of the Amendment would not have tolerated it. The Article concludes that none of these theories removed the Amendment’s reasonableness requirement.

Posted on July 22, 2025 at 7:05 AM • View Comments

The NSA’s “Fifty Years of Mathematical Cryptanalysis (1937–1987)”

In response to a FOIA request, the NSA released “Fifty Years of Mathematical Cryptanalysis (1937-1987),” by Glenn F. Stahly, with a lot of redactions.

Weirdly, this is the second time the NSA has declassified the document. John Young got a copy in 2019. This one has a few less redactions. And nothing that was provided in 2019 was redacted here.

If you find anything interesting in the document, please tell us about it in the comments.

Posted on May 19, 2025 at 7:06 AM • View Comments

DIRNSA Fired

In “Secrets and Lies” (2000), I wrote:

It is poor civic hygiene to install technologies that could someday facilitate a police state.

It’s something a bunch of us were saying at the time, in reference to the vast NSA’s surveillance capabilities.

I have been thinking of that quote a lot as I read news stories of President Trump firing the Director of the National Security Agency. General Timothy Haugh.

A couple of weeks ago, I wrote:

We don’t know what pressure the Trump administration is using to make intelligence services fall into line, but it isn’t crazy to worry that the NSA might again start monitoring domestic communications.

The NSA already spies on Americans in a variety of ways. But that’s always been a sideline to its main mission: spying on the rest of the world. Once Trump replaces Haugh with a loyalist, the NSA’s vast surveillance apparatus can be refocused domestically.

Giving that agency all those powers in the 1990s, in the 2000s after the terrorist attacks of 9/11, and in the 2010s was always a mistake. I fear that we are about to learn how big a mistake it was.

Here’s PGP creator Phil Zimmerman in 1996, spelling it out even more clearly:

The Clinton Administration seems to be attempting to deploy and entrench a communications infrastructure that would deny the citizenry the ability to protect its privacy. This is unsettling because in a democracy, it is possible for bad people to occasionally get elected—sometimes very bad people. Normally, a well-functioning democracy has ways to remove these people from power. But the wrong technology infrastructure could allow such a future government to watch every move anyone makes to oppose it. It could very well be the last government we ever elect.

When making public policy decisions about new technologies for the government, I think one should ask oneself which technologies would best strengthen the hand of a police state. Then, do not allow the government to deploy those technologies. This is simply a matter of good civic hygiene.

Posted on April 7, 2025 at 7:03 AM • View Comments

IronNet Has Shut Down

After retiring in 2014 from an uncharacteristically long tenure running the NSA (and US CyberCommand), Keith Alexander founded a cybersecurity company called IronNet. At the time, he claimed that it was based on IP he developed on his own time while still in the military. That always troubled me. Whatever ideas he had, they were developed on public time using public resources: he shouldn’t have been able to leave military service with them in his back pocket.

In any case, it was never clear what those ideas were. IronNet never seemed to have any special technology going for it. Near as I could tell, its success was entirely based on Alexander’s name.

Turns out there was nothing there. After some crazy VC investments and an IPO with a $3 billion “unicorn” valuation, the company has shut its doors. It went bankrupt a year ago—ceasing operations and firing everybody—and reemerged as a private company. It now seems to be gone for good, not having found anyone willing to buy it.

And—wow—the recriminations are just starting.

Last September the never-profitable company announced it was shutting down and firing its employees after running out of money, providing yet another example of a tech firm that faltered after failing to deliver on overhyped promises.

The firm’s crash has left behind a trail of bitter investors and former employees who remain angry at the company and believe it misled them about its financial health.

IronNet’s rise and fall also raises questions about the judgment of its well-credentialed leaders, a who’s who of the national security establishment. National security experts, former employees and analysts told The Associated Press that the firm collapsed, in part, because it engaged in questionable business practices, produced subpar products and services, and entered into associations that could have left the firm vulnerable to meddling by the Kremlin.

“I’m honestly ashamed that I was ever an executive at that company,” said Mark Berly, a former IronNet vice president. He said the company’s top leaders cultivated a culture of deceit “just like Theranos,” the once highly touted blood-testing firm that became a symbol of corporate fraud.

There has been one lawsuit. Presumably there will be more. I’m sure Alexander got plenty rich off his NSA career.

Posted on October 11, 2024 at 7:08 AM • View Comments

Adm. Grace Hopper’s 1982 NSA Lecture Has Been Published

The “long lost lecture” by Adm. Grace Hopper has been published by the NSA. (Note that there are two parts.)

It’s a wonderful talk: funny, engaging, wise, prescient. Remember that talk was given in 1982, less than a year before the ARPANET switched to TCP/IP and the internet went operational. She was a remarkable person.

Listening to it, and thinking about the audience of NSA engineers, I wonder how much of what she’s talking about as the future of computing—miniaturization, parallelization—was being done in the present and in secret.

Posted on August 29, 2024 at 11:58 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.