[noise] Question: Sending ee, es, se, ss more than once?

[Nadim Kobeissi]

Hello everyone,
I have a question which is not very important but still probably worth
addressing for completeness.

The Noise specification (in Section 7.1) specifically disallows sending `s`
or `e` more than once by a single party, and this makes perfect sense.
However, it does not seem to disallow sending `ee`, `es`, `se` or `ss` more
than once.

On the upside: I can't spot any security-related disadvantage (or benefit)
that can arise from disallowing these tokens to be sent more than once.

On the downside: Technically, this makes it so that Noise Handshake
Patterns can have an infinitely long handshake phase, which I don't find
useful or clean in terms of framework design.

I hope this won't open way to a bike-shedding discussion. In my personal
opinion, we should disallow sending these tokens more than once, unless
there's something that I'm missing.

Thank you,

Nadim Kobeissi
Symbolic Software • https://symbolic.software
Sent from office
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