Re: Going STEK-less with QUIC?

[Christian Huitema <[e-mail]>]

On 7/27/2021 11:42 PM, Martin Thomson wrote:
> On Wed, Jul 28, 2021, at 11:55, Christian Huitema wrote:
>> [...] reuse one of the NEW TOKENS as Initial CID, [...]
> Are you talking about NEW_CONNECTION_ID here?

Yes. Sorry for the confusion. (Skipping comments on the progressive 
effect of aging on Christian's brain cells.) My initial idea was for 
creating an extension frame, with the server providing a new connection 
ID for the specific purpose of use in resumption of this connection. In 
a private message, Martin Duke suggested that clients could just as well 
use one of the NEW CONNECTION ID provided by the server. Clients can do 
that today, no change in spec required.

> If you are talking about the client taking a connection ID from an old connection and using that when establishing a new connection, that's an interesting choice.  I don't think it works because it undermines the return routeability check for the subsequent connection.  The server now knows what the connection ID might be.  I can't think of an exploit for that given that the server has already demonstrated that it is on path, but we do pretty much say that the connection ID can't be predictable like that, and there are no firm requirements that the subsequent connection attempt follow the same network path in any way.

I was not suggesting that placing a specific value in the ICID replaces 
the need for tokens and checking return routeability. Now, it is true 
that the servers and the load balancers could also coordinate their 
handling of token, and achieve the desired effect of sending connection 
resumption attempts to the same server as the original connection. That 
may very well be a better design than relying on the client to put 
specific values in the ICID.

> I had assumed that the load balancer would be able to identify an initial and then route based on the Token field in that packet, rather than the connection ID.  Maybe that's too complicated, but it is something that could be used without protocol modifications.

Yes. Looks like the way to go if we want to experiment with STEK-less.

I think placing the NEW CONNECTION ID in an ICID has a different usage 
-- testing the robustness of load balancing...

-- Christian Huitema