The IESG has approved the following document:
- 'Transport Layer Security (TLS) False Start'
  (draft-ietf-tls-falsestart-02.txt) as Informational RFC

This document is the product of the Transport Layer Security Working
Group.

The IESG contact persons are Stephen Farrell and Kathleen Moriarty.

A URL of this Internet Draft is:
https://datatracker.ietf.org/doc/draft-ietf-tls-falsestart/




1. Summary

"False Start” was an attempt to reduce the latency impact of HTTPS based on 
the simple premise that the client send application data earlier in the 
handshake; to be precise clients send application data before they have 
received and verified the server's "Finished” message.  Initial measurements 
showed a 30% reduction in latency [0] I could paraphrase more of s2, but the 
authors explained the timing and the implications at the end of s2.

Note that this “experiment” was supported by Chrome, FF, IE, OpenSSL, NSS, 
and others. Some additional details:

- Chrome 20 disable it except for sites that enabled NPN.

- Firefox has (or at some point had) an NPN requirement to enable False Start.

- Safari as an additional example without the NPN requirement:
http://opensource.apple.com/source/Security/Security-55471/libsecurity_ssl/lib/sslTransport.c

- While there were patches to enable False Start with OpenSSL, it's not clear 
it was ever part of an official release.  

As far as where you should point your fingers:
- Sean Turner is the document shepherd, and;
- Stephen Farrell is the responsible Area Director.

2. Review and Consensus

There wasn’t a whole lot of discussion, primarily because "False Start” the 
implementation issues were worked out by the browsers and the WG didn’t adopt 
this draft until long after (Nov-2014).  The draft was adopted because it 
documents existing practices and provides security considerations [0]; the 
comments in the WG adoption thread were incorporated in the -01 WG version.  
The WG’s deliberations resulted in a number of changes that more accurately 
reflect deployments (i.e., dropping server-side False Start) as well as 
restricting its use to pre-TLS1.3 (see s5.2) and cipher suites (see s5.3).

One reviewer wanted all (FF-)DHE cipher suites removed because they believe 
that the downgrade protections defined in [1] are in adequate. To solve address 
this issue, the “False Start” draft requires whitelists as well as large 
groups/curves.

[0] https://mailarchive.ietf.org/arch/msg/tls/RLklpxmZ3BQRBIqWgfeUcCLhgx0
[1] https://datatracker.ietf.org/doc/draft-ietf-tls-negotiated-ff-dhe/





RFC Editor Note

 Please change the intended status in the header to "Informational"
 I don't believe any other text changes are needed. (The IESG and
 authors figured that informational was better during IESG eval.)

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