> On Apr 28, 2015, at 4:09 PM, Michael Richardson <[email protected]> wrote:
> 
> 
> Yoav Nir <[email protected]> wrote:
>>> Is this diagram correct:
> 
> some comment on the accuracy of my diagram would be appreciated :-)

I’ll get to that later.

> 
>>> I think that the IANA considerations of ipsecme-chacha20-poly1305
>>> should say
>>> something like,
>>> "According to cfrg-chacha20, Poly-1305 is not suitable for
>>> use as a PRF for IKEv2, and this specification explicitely
>>> does not allocate a code point for that.”
> 
>> That’s kind of a weird thing to write. We don’t allocate an ICMPv6 type
>> number either. It’s kind of sad because while Poly1305 is not a good
>> PRF, ChaCha20 is. But unfortunately it’s not a good PRF for IKEv2 as it
>> requires a constant-size key, and RFC 7296 requires that all PRFs
>> support any size key. Of course we could add the blake2 hash function
>> to convert any non-256-bit key to a 256-bit key, and blake2 is based on
>> the ChaCha20 block function.  But we chose not to do this. At least not
>> yet.
> 
> I predict that in two years, there will be a stream of queries from
> @gmail/@hotmail accounts asking in broken english why there isn't a PRF
> number.  I'll bet we even get an Errata filed :-)

But we’re not even creating an AUTH entry…

> The bit about ChaCha also being wrong would be useful to write down
> somewhere.

https://tools.ietf.org/html/draft-irtf-cfrg-chacha20-poly1305-10#section-2.7

Yoav

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