Yeah, 2^48 is huge, but that gets you a collision probability of ~40%.
You'd want a probability more like 1-in-a-million (or 1-in-a-billion). That's 2^39 (or 2^34), which is 1000 messages a second for 17 years (or 7 months).
Again, probably still safe for many use cases. But you do have to think about it for a second. XChaCha20's 192-bit nonce capacity lets you totally ignore that factor, which is a nice property for generic crypto recommendations.
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2^48 is an absurdly large number.
That's enough that you can generate 1000 messages a second for several millenia.
Yeah, 2^48 is huge, but that gets you a collision probability of ~40%.
You'd want a probability more like 1-in-a-million (or 1-in-a-billion). That's 2^39 (or 2^34), which is 1000 messages a second for 17 years (or 7 months).
Again, probably still safe for many use cases. But you do have to think about it for a second. XChaCha20's 192-bit nonce capacity lets you totally ignore that factor, which is a nice property for generic crypto recommendations.