Re: [TLS] [ECH] Reverting the config ID change

Carrick Bartle <cbartle891@icloud.com> Wed, 17 February 2021 00:57 UTC

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From: Carrick Bartle <cbartle891@icloud.com>
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Date: Tue, 16 Feb 2021 16:57:36 -0800
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Cc: Martin Thomson <mt@lowentropy.net>, "<tls@ietf.org>" <tls@ietf.org>
To: Eric Rescorla <ekr@rtfm.com>
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Subject: Re: [TLS] [ECH] Reverting the config ID change
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I see. It seems reasonable to me to leave it as a variable-length vector to provide flexibility. Since the best mitigation for the privacy issue, regardless of the length of the config_id, is to have a large anonymity set as described in Security and Privacy Goals, it doesn't seem like a longer config_id is, in all cases, a major privacy trade-off.



> On Feb 16, 2021, at 4:34 PM, Eric Rescorla <ekr@rtfm.com> wrote:
> 
> 
> 
> On Tue, Feb 16, 2021 at 4:21 PM Carrick Bartle <cbartle891@icloud.com <mailto:cbartle891@icloud.com>> wrote:
>>  It's not significant extra complexity to have this field bigger and it basically makes it impossible to have any structure.
> 
> What do you mean by structure? How does a byte not provide sufficient "structure"?
> 
> It's not long enough to encode much. As a concrete example, what if the label is actually an encrypted version of the private key? Or you have a distributed generation algorithm that you don't want to synchronize?
> 
> -Ekr
>