Re: [TLS] About encrypting SNI

Currently HTTPS requires the name in the cert (CN or alt-name) to match the dns name, and a wildcard can cover only one qualifier.

So if you’re hosting like tumblr, you can do yoavnir.tumblr.com and richsalz.tumblr.com and have a *.tumblr.com certificate.

But you can’t host www.yoavnir.com (not mine!) and www.imperialviolet.com like that. There is no valid certificate that won’t generate red screens that covers both of those.

So we’d have to change the way certificates are matched to domain names if we wanted that. Perhaps we could have a certificate with the name “www.myhostingsite.com”, and a new DNS record for www.yoavnir.com that says that this site is hosted with the name “www.myhostingsite.com”.  For a site that published this DNS record, the browser would not send a (clear) SNI.

This is a significant change, though. One that affects previous versions of TLS as well.

Yoav

On Apr 15, 2014, at 4:42 PM, Salz, Rich <rsalz@akamai.com> wrote:

> What if the client doesn't send SNI, but instead the hosting service has a single wildcard cert?  What changes in the privacy and trust model?  Why isn't that acceptable?
> 
> 	/r$
> 
> --  
> Principal Security Engineer
> Akamai Technology
> Cambridge, MA
> 
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