Re: [dns-privacy] [Ext] DS Hacks

[Paul Hoffman <[e-mail]>]

Thanks! If this is indeed what Ben meant, that works for me. (Apologies for being That Kind Of Person who mostly thinks in examples...)

Given the discussion yesterday, we would also want a signal for "authenticate me or die" versus "I'm fine if you can't authenticate me", but that's an easy detail to add to the format.

--Paul Hoffman

On Jul 30, 2021, at 12:29 PM, Robert Evans <[e-mail]> wrote:
> 
> If I understand correctly, the encoding could cover any below-the-cut records in the referral response.
> 
> For in-bailiwick response, this would be the child NS rrset, glue A/AAAA records, and SVCB records:
> 
> ;; Authority
> example.com [example.com] NS ns1.example.com
> example.com [example.com] NS ns2.example.com=
> 
> ;; Additional
> ns1.example.com [ns1.example.com] A 192.0.2.1
> ns1.example.com [ns1.example.com] AAAA 2001:db8::1
> ns2.example.com [ns2.example.com] A 192.0.2.2
> ns2.example.com [ns2.example.com] AAAA 2001:db8::2
> 
> There could be a DS record that contains encoded RDATA:
> rr_type=NS prefix=<empty> rdata="ns1.example.com"
> rr_type=NS prefix=<empty> rdata="ns2.example.com"
> rr_type=A prefix=ns1 rdata="192.0.2.1"
> rr_type=A prefix=ns2 rdata="192.0.2.2"
> rr_type=AAAA prefix=ns1 rdata="2001:db8::1"
> rr_type=AAAA prefix=ns2 rdata="2001:db8::2"
> rr_type=SVCB prefix=_dns.ns1 rdata="ns1.example.com 1 alpn=dot adox=tlsa"
> rr_type=SVCB prefix=_dns.ns2 rdata="ns2.example.com] 1 alpn=dot adox=pki"
> 
> (Or maybe leave out the A and AAAA records, but that makes it easier for attackers to trick resolvers into talking to malicious endpoints.)
> 
> For out-of-bailiwick response, this would be only child NS records.
> 
> ;; Authority
> example.com [example.com] NS ns1.other-example.com
> example.com [example.com] NS ns2.other-example.com
> 
> ;; Additional
> <empty>
> 
> There would be a DS record that contains encoded RDATA: 
> rr_type=NS prefix=<empty> rdata="ns1.other-example.com"
> rr_type=NS prefix=<empty> rdata="ns2.other-example.com"
> 
> This referral conveys no authenticated SVCB (only authenticated NS names), so encryption-aware recursive resolvers would query for SVCB in parallel with A and AAAA queries for the name servers.