Re: [TLS] draft-ietf-tls-esni feedback

Eric Rescorla <ekr@rtfm.com> Mon, 21 October 2019 14:41 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Mon, 21 Oct 2019 07:40:58 -0700
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To: Rob Sayre <sayrer@gmail.com>
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Subject: Re: [TLS] draft-ietf-tls-esni feedback
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On Mon, Oct 21, 2019 at 7:32 AM Rob Sayre <sayrer@gmail.com>; wrote:



> Judging by the mailing list archives, the design of the field is
>>> intentional. It's not clear to me why "zeros" wasn't specified as
>>> variable-length with a prose restriction, though.
>>>
>>
>> Because then you have a spurious length field.
>>
>
> I don't understand why it would be spurious. In this case, the
> deserializing implementation needs to inspect every byte anyway.
>

Because if you set padding to be the length of the maximum value, then a
length byte makes every message one longer.



>
>> This part of the spec is also just generally difficult to follow, in my
>>> opinion. I had no trouble following the ESNIKeys section. Perhaps the
>>> problem is in the interaction of prose order, serialization order, and
>>> procedural code order.
>>>
>>
>> Well, this structure is likely to change a fair bit, so probably not
>> worth trying to update the text right at this moment.
>>
>
> Fair enough. I would also suggest making sure that this section does not
> span a page boundary. That made things worse for me.
>

At this early stage, we usually don't worry over-much about page breaks.

-Ekr


> thanks,
> Rob
>