1459824 - Allow 0.5 RTT data from the server

Status: RESOLVED FIXED

(NSS :: Libraries, enhancement)

Description

[Martin Thomson [:mt:]]

This is relatively straightforward, but we want to be careful if the server requires client authentication.

Comment 1

[Phabricator Automation]

Attachment: Bug 1459824 - Enable 0.5 RTT data from the server, r?ekr

It turns out that we never spent the time to enable this.  It's
relatively easy to do that, so here 'tis.  The real challenge is in determining
where it is safe to send 0.5 RTT data.  I've opted to disable it only if a
client certificate is required.  If a client certificate is requested, but
optional, I figure that the server is expecting to have to query for
certificates before sending anything that it might not want to send.

I think that is sufficient for now.  However, if we ever do something like
encrypted SNI, then we might want to revise this.  I haven't thought that
through completely, but we might want key confirmation before sending out
information that might be conditioned on the server identity.  Not sure how that
could be exploited, but that seems like a place where extra caution is
justified.

Comment 2

[Eric Rescorla (:ekr)]

Comment on attachment 8973925 [details]
Bug 1459824 - Enable 0.5 RTT data from the server, r?ekr

Eric Rescorla (:ekr) has approved the revision.

Comment 3

[Martin Thomson [:mt:]]

https://hg.mozilla.org/projects/nss/rev/87b0372b6a2da431630336702ae8c2d0d0fdb04e landed in September 2018, but I neglected to close the bug here.