Re: [dnsext] Historical root keys: The Large Router Vendor Speaks

[Chris Thompson <[e-mail]>]

On Feb 1 2011, Tony Finch wrote:

>On Fri, 28 Jan 2011, George Barwood wrote:
>>
>> I think it's necessary to roll the key eventually because DNSSEC
>> signature dates wrap, (and signatures can therefore be replayed) but
>> only after 136 years.
>
>There are no dates on DNS keys so I don't understand the relevance of this
>point.

In 2011, the root zone has an RRSIG on the DNSKEY RRset signed using the KSK,
validating the current ZSK. It covers a period of a couple of weeks.

In 2147, the same time_t values (mod 2^32) come round again, and this RRSIG
can be replayed, if the root zone KSK has not changed.

Meanwhile, this year's ZSK has been compromised - we'll be able to factorise
1024-bit moduli by then, surely?

So the replay can be used to validate a compromised root zone ZSK, and we're
well away to taking over the Internet :-)

Of course, the likelihood of any of this stuff being around in 136 years time
is ... small.

-- 
Chris Thompson               University of Cambridge Computing Service,
Email: [e-mail]    New Museums Site, Cambridge CB2 3QH,
Phone: [phone]       United Kingdom.