Re: [TLS] PR#1091: Changes to provide middlebox robustness

Alex C <immibis@gmail.com> Thu, 07 December 2017 06:48 UTC

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From: Alex C <immibis@gmail.com>
Date: Thu, 7 Dec 2017 19:48:03 +1300
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To: Eric Rescorla <ekr@rtfm.com>
Cc: Yuhong Bao <yuhongbao_386@hotmail.com>, Andrei Popov <Andrei.Popov@microsoft.com>, Peter Saint-Andre <stpeter@stpeter.im>, "tls@ietf.org" <tls@ietf.org>, Tapio Sokura <tapio.sokura@iki.fi>
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Subject: Re: [TLS] PR#1091: Changes to provide middlebox robustness
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Thanks for the info. I see a pull request has just been submitted already:
https://github.com/tlswg/tls13-spec/pull/1116

On Tue, Dec 5, 2017 at 1:03 AM, Eric Rescorla <ekr@rtfm.com>; wrote:

>
>
> On Mon, Dec 4, 2017 at 1:59 AM, Alex C <immibis@gmail.com>; wrote:
>
>> The obvious problem with randomly adding fake versions is you have to
>> have a way of ensuring they won't conflict with *real* future versions -
>> and whatever pattern you decide upon in order to do that, middleboxes will
>> use that pattern to filter out fake versions, and fail as soon as you
>> present one with a real future version (i.e. TLS 1.4).
>>
>> Can I also suggest adding a section about expected middlebox behaviour to
>> TLS 1.3? That way there is a reasonable chance that TLS 1.4 won't face the
>> same issues.
>> (Or can I do that myself? I'm not really familiar with the process, sorry)
>>
>>
> Yes, you can send a a PR at:
> https://github.com/tlswg/tls13-spec/
>
> -Ekr
>
>
>> On Sat, Nov 25, 2017 at 8:21 AM, Yuhong Bao <yuhongbao_386@hotmail.com>;
>> wrote:
>>
>>> That only applies to the ClientHello.
>>>
>>> ________________________________________
>>> From: Andrei Popov <Andrei.Popov@microsoft.com>;
>>> Sent: Wednesday, November 22, 2017 11:22:23 AM
>>> To: Yuhong Bao; Peter Saint-Andre; Eric Rescorla
>>> Cc: tls@ietf.org; Tapio Sokura
>>> Subject: RE: [TLS] PR#1091: Changes to provide middlebox robustness
>>>
>>> The idea was for the client to randomly add non-existent TLS versions to
>>> supported_versions.
>>> Presumably, this will exercise the extensibility joint and prevent it
>>> from becoming unusable.
>>>
>>> I'm not convinced this new approach will help, but we know the old one
>>> required fallbacks every time a new protocol version was introduced.
>>>
>>> Cheers,
>>>
>>> Andrei
>>>
>>> -----Original Message-----
>>> From: TLS [mailto:tls-bounces@ietf.org] On Behalf Of Yuhong Bao
>>> Sent: Wednesday, November 22, 2017 11:04 AM
>>> To: Peter Saint-Andre <stpeter@stpeter.im>;; Eric Rescorla <ekr@rtfm.com>;
>>> Cc: tls@ietf.org; Tapio Sokura <tapio.sokura@iki.fi>;
>>> Subject: Re: [TLS] PR#1091: Changes to provide middlebox robustness
>>>
>>> They are basically doing a supported_versions extension with only one
>>> entry in the ServerHello.
>>> The problem with future middleboxes should be obvious.
>>>
>>> ________________________________________
>>> From: Peter Saint-Andre <stpeter@stpeter.im>;
>>> Sent: Wednesday, November 22, 2017 11:02:39 AM
>>> To: Yuhong Bao; Eric Rescorla
>>> Cc: tls@ietf.org; Tapio Sokura
>>> Subject: Re: [TLS] PR#1091: Changes to provide middlebox robustness
>>>
>>> On 11/22/17 11:16 AM, Yuhong Bao wrote:
>>> > The problem is not TLS 1.3, the problem is future versions of TLS.
>>>
>>> Would you mind explaining that in more detail?
>>>
>>> Peter
>>>
>>> _______________________________________________
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>>
>>
>