Re: [TLS] New version intolerance caused by draft-26 supported_versions change?

[Benjamin Kaduk <[e-mail]>]

On Mon, Apr 09, 2018 at 10:16:06PM +0100, Joseph Birr-Pixton wrote:
> Hello,
> 
> PR#1163 in draft-26 seems to have broken interop with previous drafts
> with a variety of deployed implementations. draft-26 and later clients
> fail with a protocol_version alert.
> 
> Affected Internet servers include:
> 
> cloudflare.com: offers draft-23, intolerant to draft-26
> www.apple.com: seemingly unwilling to negotiate any draft, but
> intolerant anyway(?)
> www.microsoft.com: same
> google.com: same
> 
> https://jbp.io/assets/tls13-logs/cloudflare.broken.txt
> https://jbp.io/assets/tls13-logs/apple.broken.txt
> https://jbp.io/assets/tls13-logs/microsoft.broken.txt
> https://jbp.io/assets/tls13-logs/google.broken.txt
> 
> In all these cases, offering TLS1.2 in supported_versions (ie, the
> pre-draft-26 behaviour) works, and TLS1.2 is negotiated:
> 
> https://jbp.io/assets/tls13-logs/cloudflare.works.txt
> https://jbp.io/assets/tls13-logs/apple.works.txt
> https://jbp.io/assets/tls13-logs/microsoft.works.txt
> https://jbp.io/assets/tls13-logs/google.works.txt
> 
> Corroboration appreciated.  It's totally possible I'm doing something stupid :)

It is not expected for draft-NN to interoperate with draft-YY, but implementations
thereof that also support TLS 1.2 should be able to negotiate TLS 1.2.
So depending on what you mean by "intolerant", there may be nothing to see here.

-Ben