[ntpwg] Stronger symmetric NTP authentication

[Bhatia, Manav (Manav)]

Dave,

> 
> 1. Your suggestion seriously compromises the intended design that the 
> extension fields must be validated by the MAC and invites a circular 
> deconstruction. The design requires that the packet be 
> validated without 
> inspection of the extension field contents.

I think we're going in circles now. 

It's a trivial implementation tweak to check that if the new
authentication scheme is employed then one of the extension fields would
carry the authentication data. I cant seem to understand how this
affects the core protocol design. We cant always assume that our digest
would only be 16 octets.

Cheers, Manav