Re: [TLS] add challenge in TLS v1.3 to prevent DDOS attack?

["Bingzheng Wu" <[e-mail]>]

Thanks for your information. I didn't know this before.
However I don't think this match my original purpose.

The tls-auth requires the client and server have PSK. 
But I want an general anti-DDOS method.
For example, this method could be used by general web browser to visit any
web sites.

Please fix me if I misunderstand the OpenVPN's method.

Thanks,
Bingzheng

> -----Original Message-----
> From: Peter Gutmann [mailto:[e-mail]]
> Sent: Monday, June 08, 2015 5:20 PM
> To: Bingzheng Wu; tls
> Subject: RE: [TLS] add challenge in TLS v1.3 to prevent DDOS attack?
> 
> Bingzheng Wu <[e-mail]> writes:
> 
> >So, could we add a challenge-response mode in TLS v1.3 to increase the
> attacker's cost ?
> 
> You don't need anything that complex, OpenVPN has for a number of years
> supported a very effective way of dealing with this, all you need to do is
> formalise that.  It doesn't really need TLS 1.3 either, since you can do
it in a
> standard extension.  OpenVPN gives it the very misleading name tls-auth,
it's
> just a use of a PSK to MAC incoming packets, so the client-hello is
> authenticated and dropped unless it has a valid MAC signature.  This has
> protected OpenVPN against a number of OpenSSL vulnerabilities (as well as
> generic port-scanning and similar), most notably Heartbleed, where any
> attempt to exploit the vuln just bounced off, because unless you have the
MAC
> key you can't get past even the first hello message.
> 
> I started work on an RFC draft for this a while back, but it got shelved
because
> of conflicts over making it OpenVPN-compatible or not, it shouldn't be too
much
> work to dig it out and finish it (albeit in a non-OpenVPN-compatible
manner).
> 
> Peter.=