Is cryptography where security took the wrong branch?

[Anne & Lynn Wheeler]

At 03:39 AM 9/10/2003 -0700, bmanning at karoshi.com wrote:
>         There are some other problems w/ using the DNS.
>                 No revolkation process.
>                 DNS caching
>                 third-party trust (DNS admins != delegation holder)

Since DNS is a online positive list .... you change the database ... and 
voila it is updated.

This is the scenario for credit cards going from pre-70s technology with 
plastic cards and the monthly revokation booklet mailed out to all 
merchants. The credit card industry transitioned to online infrastructure 
where it transactions are denied by updating the online database. It 
eliminates the revokation process, since there aren't an unknown number of 
copies of static, stale credentials/certificates floating around the world 
potentially being presented to an unknown variety of relying parties.

DNS caching is the closest equivalent of the certificate paradigm of 
static, stale copies floating around the world. The two slight differences 
are that cached stale, static entries tend to have very short lifetimes ... 
they come into creation by activities by the relying-party (not the entity 
being authenticated) and tend to have very short lifetimes .... of a few 
hours to at most a day. However, relying-parties have the choice of going 
directly to the root and obtaining the current copy .... a function 
somewhat filled in the PKI world by OCSP .... although OCSP is just a check 
about whether the current, static, stale copy in a relying-party's 
possession is current ... not what the current entry is..

 From information theory standpoint, stale, static certificates are 
logically a form of long-lived, distributed, replicated, r/o, cache 
entries.  Cache entry semantics have been studied in some detail in areas 
like distributed file systems and multiprocessor consistent shared memory 
caches, etc.  With short-lived r/o, distributed cache entires (like DNS) 
... there is a trade-off involving 1) entry life-time, 2) frequency of 
change, 3) impact of dealing with stale entry. We ran into a problem with 
doing consistent database updates over NFS (network filesystem) because 
while NFS advertises itself as item potent, most client implementations 
have this 8k cache that can be stale.

Given high value &/or low trust ... relying parties still have option of 
directly contacting root authority. And as outline, the root authority is 
also the root authority for the CA/PKIs. If you attack the root trust 
authority with false information .... then all subsequent trust operations 
flowing from that false information is suspect. Domain name system still 
has some exploits against the root database resulting in false information 
.... but since that is the root for both DNS as well as CA/PKIs generating 
SSL domain name certificates .... it is a common failure point for both 
infrastructures. It needs to be fixed, in order to improve trust on either 
the DNS side or the CA/PKI side (doesn't matter how thick you make the 
vault door .... if somebody forgot to complete the back wall on the vault).

random, unrelated refs to past life working on processor cache design, 
distributed filesystems, and distributed databases
http://www.garlic.com/~lynn/subtopic.html#smp
http://www.garlic.com/~lynn/subtopic.html#hacmp

--
Anne & Lynn Wheeler    http://www.garlic.com/~lynn/
Internet trivia 20th anv http://www.garlic.com/~lynn/rfcietff.htm
  


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