[dns-operations] Aging TLD RSA DNSKEYs...

Paul Vixie paul at redbarn.org
Mon Jan 21 00:54:00 UTC 2019


On Jan 20, 2019, 18:04, at 18:04, Viktor Dukhovni <ietf-dane at dukhovni.org> wrote:
>> On Jan 20, 2019, at 5:10 PM, Paul Hoffman <phoffman at proper.com>
>>> It would be great if the operators of TLDs with 1024-bit ZSKs that
>>> are unchanged since 2017-10-19 or earlier would consider rolling
>>> over to new keys
>> Great for whom? This is a serious question. Given that there is no
>indication that RSA-1024 can be broken in a few years without hundreds
>of millions of dollars worth of work (unless TWIRL chips exist, and
>there is no indication that they do), what is the value to the DNS of
>rolling based on your calculations?
>A fair question.  The pros are:
>  * The DNSSEC haters would not have the opportunity to sneer
>    all those long-lived 1024-bit keys.  The WebPKI has stopped
>    using RSA-1024, and NIST's key size guidelines had RSA-1024
>    only good through 2010 or so (IIRC).
>  * Even when keys are not brute forced, there is some risk of
>    keys getting disclosed by various means, sometimes unbeknownst
>    to the legitimate key holder.  So rotating keys periodically
>    is a sound practice.
>  * We don't know whether any of the TLAs can break 1024-bit RSA,
>    but the risk is taken seriously by at least some maintstream
>    cryptographers, so it seems prudent to move to stronger keys.
>  * Finally, if you never roll your keys routinely, you probably
>    don't know how to do it in an emergency.  Best to keep the
>    gears well oiled.
>On the down side, there's some operational risk of poor execution,
>but if one gets into the habit of rolling the keys regularly, and
>the process is well thought it, the risk should be very low.
>I am curious what others think...
>	Viktor.
>dns-operations mailing list
>dns-operations at lists.dns-oarc.net
>dns-operations mailing list
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