Online Cryptography Course (2017)

(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.

It is impossible to study cryptography without "all the mathematical details". You can at best implement someone's scheme, but even that is not the best idea, as you're likely to make some mistake somewhere.

I want to put a word in here for being cautious about the capabilities you can achieve in novel systems --- software developers are often working with multiple whole sieverts of novelty without realizing it --- without having a lot of the boring theory stuff nailed down.

If you're using (say) libsodium to do exactly the kind of thing 100 other developers have successfully used libsodium to do in the past, you're fine. But it takes a deceptively small and subtle set of steps to end up synthesizing a new cryptosystem (see: attempts to build secure messaging systems out of libsodium primitives) without realizing that's what you're doing.

Learn a bunch of the theory! It's important.

Google "Cryptographic Right Answers". There are a couple of different posts, but they agree on the most of the things you would look for.

Ex.: https://gist.github.com/tqbf/be58d2d39690c3b366ad or https://www.latacora.com/blog/2018/04/03/cryptographic-right...

Perhaps what you need is something like „Cryptography Engineering: Design Principles and Practical Applications“

Book by Bruce Schneier, Niels Ferguson, and Tadayoshi Kohno.

I wanted to have a better understanding of crypto, simply to feel more confident in writing programs that use existing protocols, and started 'Real-World Cryptography' by David Wong. I'm about 3/4 through, and I've been happy with it. It is light on math, but does go into it a little bit - it seems designed for the kind of person who isn't comfortable using something until they understand how it works under-the-hood, but doesn't actually need to do any under-the-hood work.

It has taught me enough that I think I could compose a protocol out of primitives that on the surface appears to do what I've intended it to do. It has also taught me that there are many subtleties that can completely break a protocol, combining primitives can lead to unexpected weaknesses, and many people who understand crypto far better than I ever will have created broken protocols out of secure primitives.

I'm not sure it's the book you're looking for, but I think it's a good book if you want to understand crypto, but not design your own.

"Secure composition" is definitely covered in the course. It doesn't talk only about the details of RSA (though there are some lectures about that), but also about what security properties different primitives satisfy, how to compose them safely, etc.

A large part of modern cryptography is figuring out secure composition.

Same here. I also took the course from Coursera a few years ago and I really enjoyed it. The conclusion? It’s hard to get it right so don’t do crypto yourself! Quite cynical, but it kinda killed my interest in pursuing it further.

Seconding this - I loved 155, 255, and 251 from Professor Boneh. He's very talented and was one of my favorite instructors for multiple years; great at explaining concepts.

Thank you for listing these!

I would like to add the thought of looking at where these elliptic curves are deployed, things like embedded devices and implementations bitcoin-core libraries for say secp256k1 [0].

Ref:

[0] Optimized C library for EC operations on curve secp256k1

https://github.com/bitcoin-core/secp256k1

In case it helps, I found this course useful as intro to elliptical curve crypto - https://youtube.com/@introductiontocryptography4223?si=O-5_a... lectures 16 and 17 in particular.

I've been registered for Crypto II on Coursera for over a decade now!

Maybe we're looking at different things, but the link appears to discuss ElGamal encryption, which is discrete log based (which means modern implementations use elliptic curves; historically it would have been discrete log in a subgroup of a large prime field). It also talks about BLS signatures, which are exclusively elliptic curve based.

By and large, anything whose security relies on discrete log can be implemented using an elliptic curve, but beginning cryptography classes treat that as an implementation detail because mostly all you need is a prime-order group, and elliptic curves can mostly be treated as a black-box prime order group.

(BLS signatures are an exception; they require a bilinear pairing, which in turn requires a special kind of elliptic curve that's not just a black-box prime order group.)

There are all sorts of great algebraic geometry tricks to be played with elliptic curves, but those almost certainly aren't going to be found in an intro crypto class, or maybe any CS class...

Count me in!

Thanks for sharing Shane, and nice to see companies engaged with the community on a technical level!