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Re: [TLS] Security review of TLS1.3 0-RTT

Viktor Dukhovni <ietf-dane@dukhovni.org> Tue, 02 May 2017 18:33 UTC

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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [TLS] Security review of TLS1.3 0-RTT
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> On May 2, 2017, at 2:15 PM, Colm MacCárthaigh <colm@allcosts.net> wrote:
> 
> In that case, I only reason I see to stop using tickets multiple times is to protect
> the obfuscated age. It reads to me like its purpose would just be defeated. Is it
> really that hard for clients to use a 1-for-1 use-a-ticket-get-a-ticket approach?

Yes, it is difficult to do 1-for-1.  In postfix there are parallel client processes
reading a shared session cache, and parallel writers updating that cache, and without
major changes to the code, when two writers update the cache back to back only one
ticket (really SSL_SESSION object) is saved.  Under load, many clients would not
find a ticket at all.

-- 
	Viktor.

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