Re: [TLS] A flags extension

[Hubert Kario <[e-mail]>]

On Monday, 25 March 2019 22:09:35 CET Yoav Nir wrote:
> Hi.  Today at the TLS meeting, there was a discussion at the mic about 1-bit
> extensions that only serve to indicate support for an optional feature. EKR
> commented that such extensions take 4 bytes each and that maybe we need to
> replace them with a flags extension.
> 
> So I threw together a quick -00 draft with an extension that does just that
> [1].
> 
> Comments are welcome.

I don't think that "penny-pinching" the 4 bytes necessary to send a flag is 
worth the interoperability problems, and increased complexing of parsing 
Client Hello. Especially if we go the route of actual bit flags.

I think the likelihood of bugs in that code over the possible bytes saved 
makes it a net negative.

yes, TLS is quite chatty protocol, it could encode values much more tightly, 
but I think we all remember the bugs related to ASN.1 parsing from inside of 
PKCS#1 v1.5 signatures
-- 
Regards,
Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 115, 612 00  Brno, Czech Republic