Subject: [TLS] TLS Cross-SNI Resumption

From: Victor Vasiliev <[email-masked]>
Date: Sun, 12 Jul 2020 17:23:06 -0400

Hello everyone,

As some of you might remember, we've had multiple discussions in the past
about letting the clients do session resumption in cases when the SNI value
changes, but the original certificate is also valid for the new SNI.
Originally we talked about this
<https://github.com/tlswg/tls13-spec/pull/1080> during TLS 1.3
standardization; the conclusion back then was that resumption across
domains is fine in principle, but the extension used to opt into it should
be shipped in a separate document.

One such document was proposed back in Prague:
https://tools.ietf.org/html/draft-sy-tls-resumption-group-00.  That draft
unfortunately hasn't progressed since;  I've tried contacting the author
back in March, but got no response.

I wrote a draft that does a similar thing:
https://tools.ietf.org/html/draft-vvv-tls-cross-sni-resumption-00.  This
introduces a NewSessionTicket extension, which was the original approach
proposed back in PR#777 <https://github.com/tlswg/tls13-spec/pull/777>
(draft-sy-tls-resumption-group used CH/SH extension).

What do people think about this?

Cheers,
  Victor.