Re: [secdir] review of draft-hollenbeck-rfc4933bis-02

[Alexey Melnikov <[e-mail]>]

Hi Tim,

Polk, William T. wrote:

> I’m a little late to the party, but I have been quietly mulling over 
> this problem as well. Now that Sandy has explicitly asked for an AD to 
> step in, I figured I should participate more actively. I have also 
> added Nico Williams to the CC list (my apologies, Nico) since channel 
> bindings is really his area of expertise.
>
> I think there is a real need for channel bindings with some 
> applications of EPP, but may not always be strictly necessary in other 
> cases. For example, the e-Automation project for the administration of 
> DNS root zone uses EPP but if I recall correctly most of the objects 
> that are transferred are digitally signed objects. In this case, 
> channel bindings are perhaps less important since we aren’t relying 
> solely on the EPP authentication mechanism. So, in my opinion we 
> should encourage their use but should not require channel bindings.

>
> However, if the application is relying on EPP in combination with 
> transport for security, channel bindings would provide significantly 
> enhanced security. That says channel bindings deserves to be mentioned 
> and a little guidance on (1) implementing channel bindings and (2) 
> determining when channel bindings is required. That begs a new 
> question of course – where does this information go?

Nico's response confirmed what I was thinking about this myself: for EPP 
running over TLS over TCP (4934bis), channel bindings are not required, 
because TLS authentication is mandatory and because TLS server 
certificate verification procedure is also mandatory.
So I don't think there is an issue with 4934bis document.

> I am starting to believe that the security considerations section of 
> 4930bis should note that enhanced security SHOULD be achieved through 
> channel bindings unless the application involves digitally signed objects,

I think another alternative can be to require mutual TLS authentication 
in a transport protocol mapping document.

> and that the TLS usage section of 4934bis (section 9) should include a 
> pointer to techniques for implementing channel bindings with TLS.

As per my coment above, I don't think this is needed.
Besides adding channel bindings to EPP would require an extension to EPP 
itself.

> I am still mulling this over, and will probably not enter any discuss 
> until tomorrow, but this seems the best approach. (Hopefully Nico will 
> weigh in before then and keep me straight on this one...)