Re: [DNSOP] New Version Notification for draft-wessels-dns-zone-digest-01.txt

["Paul Hoffman" <[e-mail]>]

On 26 Jul 2018, at 10:25, Ondřej Surý wrote:

>> If the ZONEMD record is signed, the only person who can mount a 
>> collision attack is the zone owner themselves. If the ZONEMD record 
>> is unsigned, an attacker can just remove it.
>
> I believe, that’s not true.  The ZONEMD can stay intact while the 
> attacker would modify the unsigned parts of the zone to create a same 
> checksum, but different contents?  He might be targeting just this 
> particular zone and it’s delegation, so everything else is 
> throw-away junk that can be modified.
>
>> What is the attack you are envisioning?

You didn't answer the last question. It sounds like you want it as a 
signature over the entire zone. If so, then I fully agree that using 
hash algorithms that have known collision attacks is a very bad idea. 
But I also think that using ZONEMD as a strong signature is a bad idea: 
that's what signing algorithms are for.

--Paul Hoffman