Re: [Cfrg] I-D Action: draft-nir-cfrg-chacha20-poly1305-01.txt

[Ted Krovetz <[e-mail]>]

Hello Yoav,

Nice work on draft-nir-cfrg-chacha20-poly1305-01.txt. It's a useful document. I wonder, though, if endian conventions are clear enough. What exactly is a little-endian integer? (I thought there was only one kind of integer.) I think you mean that keys, etc, residing in memory are read little-endian, 32-bits at a time. But, what if these quantities do not come from memory? What if the nonce, or key, or counter happens to be a computed value and resides in registers? When exactly do these need byte reversal? As an example, when you talk about the counter being 1, is that 00:00:00:01 in memory, which then becomes 01:00:00:00 in a register, or vice-versa? I was able to figure it out by looking at your examples, but it might be better if it were made clearer and didn't *need* looking at examples.

One approach you might consider is defining the interfaces as taking plain old integers, but then writing a note that explains how big-endian and little-endian systems would interact with such an interface to get standard behavior.

Damn Intel for making the world primarily little-endian! It's such a pain.

Cheers,
Ted