Re: [TLS] Further TLS 1.3 deployment updates

Adam Langley <> Fri, 14 December 2018 19:25 UTC

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From: Adam Langley <>
Date: Fri, 14 Dec 2018 11:25:12 -0800
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To: Nico Williams <>
Cc: David Benjamin <>, "<>" <>
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Subject: Re: [TLS] Further TLS 1.3 deployment updates
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On Fri, Dec 14, 2018 at 10:50 AM Nico Williams <>;

> If the server rejects resumption I guess the client would still fail,
> but this is much better than failing at 100% of all resumptions and
> better than adding fingerprinting and downgrades.

In order for TLS 1.3 deployment to be viable the failure rate needs to be
negligible. It's not feasible to construct things such that moving traffic
across session caching domains causes a wave of handshake failures.
Additionally, if we were to wait for these versions of Java to die out in
the ecosystem, we risk other buggy clients getting established in the mean
time. We are painfully aware that limiting our server-side deployment
allowed this bug to become established and, while we did it to ease
middlebox issues, it may have been a mistake.



Adam Langley