> the logic used here is alarming.

Why? I agree that a larger nonce would be better and that's possible, but even with a larger nonce not having sudden total compromise of authentication on nonce duplication would be a good thing would it not?

Even with larger nonces/IVs nonce reuse can still be an issue. If you store your counter/seed, storage can be corrupted. If you store your counter/seed, your VM can be cloned creating an exact copy of your counter/seed. If you rely on system entropy you can have entropy issues. The latter is fairly common on small and embedded devices including a ton of ARM boards that are on the market. I have actually seen cheapo ARM boards that ship with kernels where /dev/urandom outputs the same bits at boot every time. I imagine it's a combination of disabling every ad-hoc entropy source option in the kernel parameters (because code size!) combined with no non-volatile clock and no hardware entropy source and a very deterministic single in-order core.

Sudden death properties are a footgun and I'm a little surprised that constructions with this property have become the standard. Increasing the size of the nonce/IV just makes the footgun's trigger less squirrely.

This post (I'm the author) is just research notes posted for feedback, not a final design that is shipping. (I edited the post and added a disclaimer just in case people get confused about that.) My goals are four-fold: (1) to avoid sudden death properties entirely, (2) to be fast (on modern hardware with AES acceleration, which pretty much all targets where performance matters), (3) to be potentially FIPS-certifiable if I plug in FIPS libraries/modules for my primitives, and (4) to avoid adding more packet overhead if possible. My thought is that if (1) is achievable then (4) is also achievable.

<rant>

I really find the fear-mongering around crypto to be counterproductive. This post is just an idea, and the problem it is attempting to address is a real one. No, I don't like FIPS either, but I do like making money and numerous large clients do require it. So why not research ways to be FIPS compliant and be better than the average FIPS-compliant (stock AES-GCM with sudden death footgun) implementation? Why is that goal alarming?

Every time I discuss crypto I get people who just chime in with "don't write crypto, just use standard stuff." (I do agree that it's best to use standard stuff if it meets all your goals, that's not the point.)

What does saying that actually accomplish?

The people who really shouldn't write crypto will ignore it because they think they know more than they really know (or their boss is telling them to). The people who should write crypto will ignore it because it doesn't apply to them. The only people who will follow those kinds of admonitions are the people who don't know crypto and know they don't know but want to learn, and they'll be discouraged from doing so.

I learned about crypto because I realized it was hard, ignored this kind of advice, and read and listened to people who did understand it. When I ask questions about crypto or post ideas for feedback I've learned to only pay attention to replies that contain specific information or point out actual specific issues or flaws in a design. I ignore hand-wavey fear mongering that contains no actual content, and I'd encourage others who are interested in learning about crypto or anything else to do the same.

</rant>