Re: [MMUSIC] Alissa Cooper's No Objection on draft-ietf-mmusic-4572-update-12: (with COMMENT)

[Christer Holmberg <[e-mail]>]

Hi Alissa,

Thank you for your review! See below.

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COMMENT:
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>Section 5.1 says:
>
>  "An endpoint MAY, in addition to its more preferred hash function,
>   also verify that each certificate used matches fingerprints
>   calculated using other hash functions.  Unless there is a matching
>   fingerprint for each tested hash function, the endpoint MUST NOT
>   establish the TLS connection."
>
> This seems a little weird to me. It's up to the endpoint to decide whether to check for errors, and then if it 
> does find an error it can't setup the connection, whereas if it just hadn't checked it would be able to setup 
> the connection. I think it would help to explain why an endpoint would be motivated to check multiple fingerprints.

I think the only use-case that came up was a situation where the receiver is not sure which hash function is the "strongest", and therefor checks multiple. However, it was also realized that with the multiple set of hash functions such situation is very unlikely to occur.

So, I could add the following note:

"NOTE: An endpoint might choose to match each used certificate against fingerprints calculated using multiple
hash functions e.g, if the endpoint is unsure which hash function is the strongest."

...or we could simply delete the text. I personally would go for that, but in case others want to keep it I have no problem with that.

Regards,

Christer