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Re: Rethink CRLs

At 10:13 AM 8/15/96 +1000, Michael Warner wrote:

>There is some curiosity value to a human, but the reaction for all three
>should probably be the same.   If you suspect a key has been compromised,
>you cease to use it.   Even if you "get it back", the fact that it was "in
>the hands of the enemy" means it should be considered compromised.
>In which case the behaviour you wish to encourage by issuing CRLs in the 
>above three examples are:
>1) don't trust the certificate after <date>
>2) don't trust the certificate after <date1>
>3) don't trust the certificate after <creation-date>
>I believe this approach is both simpler to deal with, and also encourages
>a more sensible security policy.

I can buy your simplification -=- although I can imagine a real scenario
under which (2) might be real.  That is, the private key is locked in a
tamper-proof enclosure which is mislaid for a few days -- then turns up.
[This happened with a US cipher device (SIGABA) during WW-II.]  Once you get
it back, you can tell if there has been a tamper attempt.  The enemy might
have had it or might not -- and *might* have used it during the period it
was missing, but could not have copied the key.

 - Carl

|Carl M. Ellison          cme@cybercash.com   http://www.clark.net/pub/cme |
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