Changing the DNSSEC algorithm

[Petr Menšík]

Hi Danilo,

I think the way you have describe should work. But can I ask what source
this recipe has? I have seen recently similar signing in one of our
test. I guess this should be from public recipe. Would you share its
origin, please?

I would recommend having DNS server do the job of maintaining
signatures. If you do it this way manually, you have to resign your zone
each time your signatures expire. Do you have set some kind of reminder
to remind you?

I would try DNSSEC guide [1] with bind 9.16 or more recent. It provides
a policy inside named. It depends on what version do you have. Even 9.11
can maintain signatures [2] and resign them, but the process is more
complicated. You would have to just regenerate keys, otherwise it will
maintain your signatures. But yes, it won't be able to edit zone file by
hand this way.

Read dnssec-settime manual page and way to set times, when each key
should be activated or deactivated. It should be more safe if done the
right way. You can use dnssec-signzone -S to use smart signing and then
omit step 2. Just provide correct directory to keys. But I admit it
might be simpler to do it manually if you would upgrade just single
zone, which has no high impact in case of error.

Btw. it seems really clumsy to read 1000 characters from proper entropy
source and then use just 16 hexcoded chars from it. /dev/urandom might
be better source and 16 bytes should be enough.

Regards,
Petr

1. https://bind9.readthedocs.io/en/v9_16_27/dnssec-guide.html

2.
https://ftp.isc.org/isc/bind9/cur/9.11/doc/arm/Bv9ARM.ch04.html#dnssec.dynamic.zones

On 4/5/22 09:07, Danilo Godec via bind-users wrote:
>
> Hello,
>
>
> I implemented DNSSEC for my personal domain a good while ago with an
> older Bind and back then, I used RSASHA1-NSEC3-SHA1 algorithm, which
> by now is not recommended... So I'm going to change the algorithm,
> probably to ECDSAP256SHA256, which should also be NSEC3 capable.
>
> Since my domain is small and rarely changes, I'm not using any fancy
> updating features - I manage it manually, by editing the non-signed
> version of the zone file and then signing it to create a signed version.
>
>
> Here I'd like to verify that I understand the steps required to change
> DNSEC key / algorithm without disruption:
>
>
> 1. create new keys for my zone
>
>   * dnssec-keygen -a ECDSAP256SHA256 -n ZONE mydomain
>   * dnssec-keygen -f KSK -a ECDSAP256SHA256 -n ZONE mydomain
>
>
> 2. include new keys in my zone while keeping old keys too:
>
>     $INCLUDE Kmydomain.+008+14884.key         <- old key
>     $INCLUDE Kmydomain.+008+27618.key         <- old key
>     $INCLUDE Kmydomain.+013+10503.key         <- new key
>     $INCLUDE Kmydomain.+013+39532.key         <- new key
>
>
> 3. sign the zone file
>
>     /usr/sbin/dnssec-signzone -A -3 $(head -c 1000 /dev/random |
> sha1sum | cut -b 1-16) -e +3024000 -o mydomain -t mydomain.hosts
>
>
> 4. ask the registrar to add new DS record to TLD (I have to do this by
> mail, there is no 'self-service' UI)
>
> 5. wait at least one TTL (making sure to use the longest TTL in my zone)
>
> 6. ask the registrar to remove old DS record(s) (I don't quite
> remember why, but I had two)
>
> 7. wait another TTL period
>
> 8. remove old keys from zone
>
> 9. re-sign the zone
>
>
> Will that be OK?
>
>
>    Best regards,
>
>      Danilo
>
>
>
-- 
Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemensik at redhat.com
PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB
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