What’s *not* Changed in a Year


A minor (personal) milestone — I’ve collected DNSSEC data for the root and TLDs for 366 days (1 year because of the leap day).  During the collection I’ve done periodic analysis to see how DNSSEC is being driven by experts and have given a number of presentations on what’s been happening.  How DNSSEC is being run?  How do the operations differ from what the protocol engineers and RFC writers forecasted?  There are presentations in the archives for APRICOT, ICANN, IEPG, RIPE and CENTR meetings that have been held this past winter and spring that cover these questions from different angles.

Now, at the one year mark, for fun, a look at what’s not changed.

Not so noteworthy, because KSK’s are expected to be used on the order of years, these records have been a constant:

  • 70 DNSKEY records holding SEP/KSK’s
  • 44 DNSKEY RRSIG records, usually signed by SEP/KSK’s
  • 46 DS records in the root

But these fairly noteworthy:

  • 6 RRSIG records for NSEC/NSEC3PARAM and SOA
  • 9 DNSKEY records holding ZSK’s (not alarming, but…)
  • 40 NSEC3PARAM – specifically 40 unchanged salts

First an explanation is needed (as usual when analyzing any set of data) – when I write that an RRSIG is unchanged, that refers to the signed-by fields and not the signature payload itself.  The TLDs are refreshing signatures as needed, but when the key isn’t changed (as well as some other parameters) my analysis considers the RRSIG to be the same.

What this analysis says is that there are 6 TLDs that have used a ZSK for a full year to generate signatures. Each of the 6 keys is RSA-SHA1 and 1024 bits long. So some are challenging the (“CW”) notion that long lived keys will break. Publishing a ZSK for a year (per se) is not risky, but it shows that at least 9 ZSK’s have a longer lifetime that expected.

Besides the 6 ZSK keys that signed every day, the other three, two never generated signatures and one did so over about a 9 month period.

The 40 unchanged NSEC3PARAM records indicate that 40 TLDs have run NSEC3 for a year (plus) and have not changed the salt (as opposed to the 4 TLDs that change the salt daily or nearly daily).  The RFC recommends “with every signing” but few do “batch” signing anymore.

Final note – these counts do not cover the TLDs that have begun operations within the past 366 days.

Ed Lewis

Director, Member of Technical Staff at Neustar

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