Assumption about TLSA records
ietf-dane at dukhovni.org
Thu Apr 20 16:52:19 CEST 2017
On Thu, Apr 20, 2017 at 09:27:49AM -0400, John Allen wrote:
On Thu, Apr 20, 2017 at 09:34:27AM -0400, John Allen wrote:
On Thu, Apr 20, 2017 at 09:36:34AM -0400, John Allen wrote:
> Is the following assumption reasonable?
> if there are multiple TLSA dane-ee (type 3) records for a particular
> service, none of which match the current generated record, they can
> (maybe should) be deleted.
> The same "rule" can be could be applied to dane type 2 records.
At all times, TLSA *RRsets* whose TTL has not yet expired (vended
by either the primary or a secondary nameserver) need to contain
at least one RR which matches the *current* certificate chain of
the SMTP server.
To achieve this, the TLSA RRset stored in the master database
needs the both the *current* certificate chain and any *new*
certificate chain planned for deployment within the cache
lifetime of recently served DNS responses.
There is no logical or de jure requirement to serve TLSA records
that match *old* no longer deployed certificate chains. As soon
as the certificate chain is replaced the old records should go.
In other words, the TLSA records reflect current and near-future
certificate chain state, they need not and should not retain past
P.S. I deliberately said nothing about the certificate usage value,
it should be clear why.
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