Re: [TLS] SNI and tickets and resumption

Adam Langley <agl@imperialviolet.org> Fri, 08 August 2014 20:28 UTC

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From: Adam Langley <agl@imperialviolet.org>
To: "Salz, Rich" <rsalz@akamai.com>
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Subject: Re: [TLS] SNI and tickets and resumption
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On Fri, Aug 8, 2014 at 1:18 PM, Salz, Rich <rsalz@akamai.com> wrote:
> Can a client connect with an SNI extension and then later on resume or send
> a ticket with a different SNI value?

In practice, often yes. However, whether you want to allow that is a
different matter. If you share ticket keys between different servers
you would want to ensure that a client's connection to one of them
can't be redirected to another unless the servers are identical.

At Google, we share ticket keys between servers, but the servers will
reject a resumption if any part of the ClientHello causes a different
certificate to be selected than was presented on the original
connection. Then services that don't route requests based on the Host
header are then given their own certificates to partition them.


Cheers

AGL

-- 
Adam Langley agl@imperialviolet.org https://www.imperialviolet.org