CGA-TSIG is a possible solution to the "secure-provisioning" problem. The IPv6 
CGA address contains a hash of a public key used to secure the service. If the 
address is provisioned in a secure manner, then the client can authenticate the 
resolver, by verifying that the resolver's certificate matches the hash in the 
IPv6 address. I am not sure that this is the best solution, but it is certainly 
more secure than pointing the resolver to "8.8.8.8" and later observing that 
this is in fact rerouted to the Turkish police.

This kind of provisioning is a tradeoff. The main advantage is to not create a 
new provisioning channel. No need to be bothered with entering a certificate, 
entering the address suffices. But of course the flip side is that it only 
works if we update the DNS client and the resolver. If we do change the client 
and resolver, a number of alternatives can be used, such as:

* Use the same trick as CGA but encode the hash of the certificate as a name 
part, e.g. "AF4563ED0B561.example.com". This is probably easier to use than 
CGA, because names are less restricted than addresses. 
* Use Secure DNS, or DANE, to verify the resolver certificate.

Both of these approaches have the same property of reusing an existing 
provisioning channel. The DANE approach is probably easier to manage, because 
both the "hash in the address" and "hash in the name" approaches have a hard 
time dealing with certificate renewal.

But, yes, solving the "secure provisioning" issue would be nice.

-- Christian Huitema

 

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