Re: [hybi] Handshake was: The WebSocket protocol issues.

[Adam Barth <[e-mail]>]

On Mon, Oct 11, 2010 at 2:04 PM, Ian Hickson <[e-mail]> wrote:
> On Mon, 11 Oct 2010, James Graham wrote:
>> So there is an underlying issue here that I don't understand. It seems
>> clear to me that Adam and Eric's proposed handshake has a better
>> security story with regard to cross-protocol attacks than -75, -76, or
>> any other proposal other than using NPN with TLS. However there seem to
>> be a number of people who have problems with this proposed handshake to
>> the extent that they are prepared to forgo the security properties in
>> order to get something different. In general people seem to be aware
>> that they are making the security weaker since the arguments are mostly
>> about how different approaches will probably be good enough in practice
>> even though they are theoretically inferior.
>>
>> What I haven't followed is what the problems with the proposal actually
>> are. I understand that I have likely missed these in other messages, but
>> it would be helpful if people who believe that the proposed approach, or
>> aspects of it, are unworkable could summarise the outstanding issues
>> they see.
>
> I would like to ask a similar question, but to the people proposing Adam
> and Eric's latest proposed handshake. What real problem does it solve that
> NPN with TLS doesn't solve? As you say, it is weaker than NPN with TLS, so
> why not just go all the way?

I'd prefer to use TLS+NPN, but we put forward the newer proposal as a
compromise.  Technically, the cost of using NPN+TLS is one additional
network RT and the need to involve/update your TLS library to set up a
WebSocket server.

> This would have multiple advantages beyond just being more secure, for
> example we could halve the number of schemes we're introducing, halve the
> number of handshake implementations on both clients and servers, greatly
> reduce the testing burden, etc.

Indeed.

Adam