Category Archives: cryptanalysis

No, RSA Is Not Broken

Posted on by

I have been seeing this paper by cryptographer Peter Schnorr making the rounds: “Fast Factoring Integers by SVP Algorithms.” It describes a new factoring method, and its abstract ends with the provocative sentence: “This destroys the RSA cryptosystem.”

It does not. At best, it’s an improvement in factoring — and I’m not sure it’s even that. The paper is a preprint: it hasn’t been peer reviewed. Be careful taking its claims at face value.

Some discussion here.

I’ll append more analysis links to this post when I find them.

EDITED TO ADD (3/12): The latest version of the paper does not have the words “This destroys the RSA cryptosystem” in the abstract. …

Continue reading No, RSA Is Not Broken→

Military Cryptanalytics, Part III

Posted on by

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…

Continue reading Military Cryptanalytics, Part III→

Cellebrite Can Break Signal

Posted on by

Cellebrite announced that it can break Signal. (Note that the company has heavily edited its blog post, but the original — with lots of technical details — was saved by the Wayback Machine.)

News article. Slashdot post.

The whole story is puzzling. Cellebrite’s details will make it easier for the Signal developers to patch the vulnerability. So either Cellebrite believes it is so good that it can break whatever Signal does, or the original blog post was a mistake.

EDITED TO ADD (12/22): Signal’s Moxie Marlinspike takes serious issue with Cellebrite’s announcement. I have urged him to write it up, and will link to it when he does…

Continue reading Cellebrite Can Break Signal→

Zodiac Killer Cipher Solved

Posted on by

The SF Chronicle is reporting (more details here), and the FBI is confirming, that a Melbourne mathematician and team has decrypted the 1969 message sent by the Zodiac Killer to the newspaper.

There’s no paper yet, but there are a bunch of details in the news articles.

Here’s an interview with one of the researchers:

Cryptologist David Oranchak, who has been trying to crack the notorious “340 cipher” (it contains 340 characters) for more than a decade, made a crucial breakthrough earlier this year when applied mathematician Sam Blake came up with about 650,000 different possible ways in which the code could be read. From there, using code-breaking software designed by Jarl Van Eycke, the team’s third member, they came up with a small number of valuable clues that helped them piece together a message in the cipher …

Continue reading Zodiac Killer Cipher Solved→

Denmark, Sweden, Germany, the Netherlands and France SIGINT Alliance

Posted on by

This paper describes a SIGINT and code-breaking alliance between Denmark, Sweden, Germany, the Netherlands and France called Maximator: Abstract: This article is first to report on the secret European five-partner sigint alliance Maximator that started in the late 1970s. It discloses the name Maximator and provides documentary evidence. The five members of this European alliance are Denmark, Sweden, Germany, the… Continue reading Denmark, Sweden, Germany, the Netherlands and France SIGINT Alliance→