Subject: Re: [TLS] Encryption of TLS 1.3 content type

From: Peter Gutmann <[email-masked]>
Date: Mon, 28 Jul 2014 04:08:35 +0000

Yoav Nir <[email-masked]> writes:

>I believe that changing the 5-byte record header will cause us trouble. 
>Passive IDS/IPS devices follow TLS streams to detect certain attacks. They 
>will cut connections. 

Is it really up to the TLS WG to break (or at least constrain) our designs
in order to accomodate broken middleboxes?  They're not going to understand
any of TLS 1.3 anyway and will need to be updated when it comes along, so why
keep this legacy header just for them?

Peter.

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From: Yoav Nir <[email-masked]>
Date: Mon, 28 Jul 2014 10:40:03 +0300

> keep this legacy header just for them?

It is up to the TLS WG to design something that works on the Internet. And the Internet is full of middleboxes.

When they were updated to tolerate TLS 1.1/1.2, some may have version tolerance for forward versions as long as the first byte in 0x03. In looking for abnormally long or short records or for a malformed stream, they may drop any new TLS 1.3 header that doesn’t look like a TLS header.  That kind of thing made WebSockets far less viable than people hoped.

And these middleboxes are not always updated in a timely manner.

Yoav

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From: Michael StJohns <[email-masked]>
Date: Mon, 28 Jul 2014 12:01:15 -0400

> keep this legacy header just for them?

It depends on how widespread they are, and how deep they go into the 
packet.  If this is something that consumer NAT routers do, then its a 
big problem.  If this is something that commercial firewalls do, then 
its a big problem.

If TLS1.3 does not work on the networks deployed today,  I would doubt 
that TLS 1.3 would be deployed in any major way in any time less than a 
decade.

I don't know the reality of whether or not this will be a problem, but 
simply saying that it's not our problem is probably not useful. Data 
would be helpful.

Mike

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