Nelson B <[EMAIL PROTECTED]> writes:
> Ah, I was wondering when paradoxes would enter this discussion.
> CA self revocation:  Everything I say is a lie.
>
> "I think not" said Descartes, who promptly vanished.

the original scenario was that CA could only assert that they were no
longer valid ... they could never assert the reverse. So only a valid
CA could declare themselves no longer valid ... or bad guys that had
compromised the private key could declare the CA no longer valid ...
but the inverse couldn't be asserted.

so if the bad guys wanted to do a DOS after having compromised the
private key ... then they could, at most, declare the CA no longer
valid ... which by definition is what you want to happen anyway when a
key has been compromised.

the other thing that they could do ... was hope that the CA went
unrevoked as longer as possible ... so that they could use the
compromised private key to generate fraudulent certificates.

However, specifically with respect to revoking a CA ... you could
either do it or not do it ... nobody could ever undo it.

So the bad guys could either say nothing (about the CA) or lie about
the CA by using the compromised private key to revoke the CA. However,
by definition, if the private key has been compromised then what you
want anyway is a revokation of the CA.

The only thing that the valid CA could do is say nothing (about
themselves) or revoke themselves. If the real CA has made a decision
to revoke itself ... then there isn't much else you can do about it.

In any case, self-revokation is a special case of "everyhing else I've
said is a lie". Once it asserts that special case ... then it is no
longer able to assert anything more (and somewhat immaterial whether
that special case was a lie or not).

-- 
Anne & Lynn Wheeler | http://www.garlic.com/~lynn/
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