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Comment by ilya_m | Hacker News Reader

(Writing as a professional cryptographer.) Schneier's "Applied Cryptography" is about as useful for learning about cryptography as "The Da Vinci Code" for learning about Renaissance. It is a lively book that name-checks relevant concepts, and may even lead someone to develop interest in the actual stuff. (That was my gateway to cryptography!)

Mention Schneier at a gathering of cryptographers, and you'll elicit groans and eye-rolls. The main reason for that is that his book creates an illusion of understanding without instilling tthat it covers literally 1% of what one needs to seriously work in the field. It is also ~30 years old, and was dated even when it appeared.

This is not to diminish the fact that Schneier is an excellent communicator and has done a great service to the security field by being a consistent and effective critic of the domestic security apparatus.

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When you say "Mention Schneier," do you mean Schneier himself or Applied Cryptography specifically? I was unaware of any particular generalized disdain for the man, though I'm certainly aware of plenty for the book, which you've summarized quite well.

I remember in the intro to one of his later books (Cryptography Engineering, I think), Schneier actually apologized for making a book that was in many ways quite dangerous, and said his newer work was in an effort to make something a bit more focused on providing people with the firm foundations they'd need to do responsible work in cryptography.

That said, Applied Cryptography is a very inspiring book in many ways (which is both the best thing and worst thing about it, because it's not obvious upon reading it just how unprepared the reader is to act on that inspiration). I really wish someone would go write a new Applied Cryptography that dreams and inspires as much, but balanced with perspective and caution, and based on more recent developments.

The authors had some weird blind spots, even for the time, when Practical Cryptography (now called Cryptography Engineering) was published --- curves and authenticated encryption seem like the two obvious examples.

The cryptographer Dan J. Bernstein once told me a story that Bruce Schneier kept some cryptographic protocol secure for an additional 24 hours. The researcher demonstrating this protocol's weakness based their proof-of-concept on a proof in Schneier's book. However, Schneier's description contained a mathematical error. When the error in the proof-of-concept was pointed out to the researcher at the conference, this researcher went back to their hotel room, discovered the origin of the error in Schneier's text, and fixed the proof-of-concept for the conference-goers by the following day. Thus, Bruce Schneier kept a cryptographic protocol secure for an additional 24 hours.

I'm surprised to hear that. I have never read Applied Cryptography, but I find that an incredibly damning simile (though maybe it wasn't intended to be?). Didn't Schneier develop Blowfish?

> an incredibly damning simile

I stand by my comment, however harsh it may seem. Some of the disdain held by cryptographers, especially of a certain generation, is in no doubt a reaction to Schneier's prominence in the public eye as Mr. Crypto. The fact that he is highly quotable and media-savvy makes him a go-to person whenever a comment is needed on something (anything!) happening in security.

What is a better book? I don't want anyone eye-rolling when I'm LARPing.

"Serious Cryptography" is good. There's an updated edition dropping later this year.

"Real World Cryptography" is also good.

A better book for what audience? The scientifically minded can do much worse than "A Graduate Course in Applied Cryptography" by Dan Boneh and Victor Shoup (on which the online cryptography course is based). For a more practical angle, I agree with other commenters on this thread: "Cryptography Engineering" (Ferguson, Schneier, Kohno), "Serious Cryptography" (Aumasson) and "Real-World Cryptography" (Wong) are pretty solid.

What LARP involves academic comparisons of cryptographic algorithms? Whatever it is, it sounds like my sort of thing ;)

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