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Re: More on OCSP and CSL



Antonio Lioy wrote:
 
> This is another view: the CSL is being used as a waiting
> list for possibly revoked certs. If it is later revoked,
> then you'll put it in the CRL, otherwise you'll remove it
> from the CSL.
> 
> But I disagree with this view: if I temporarily lost control
> of my smart-card, I can never know what has happened during
> that period of time.

Yes, but I think that if you are not sure about some misusage
of the private key, then you should request it to be revoked.

This is for two reasons: the first is about how long a CSL will
become if we keep track about every suspension of certificates
and the second is about your trusting in your key-pair.

If we keep every suspension tracked on the CSL, it can get a
very long list and it could suffer from problems related to
this aspect (distribution, definition of delta's CSL, and so
on... ). I'd like to avoid these problems as them tend to
get the CSL more complex than needed.

The second aspect is related on the fact that if you do not
trust your key for a certain period, than you should not trust
it at all because it could be open to every kind of attacks:
let's say someone discovers your password and uses it non only
when it is suspended, but he/her can get in touch with your key
during the working time when you are having a coffe-break...

If you are now trusting your key it is possible you think that
the 5 mins of a coffe break do not represent a real danger...

So my vision is: if you trust your certificate is because it has
never been in danger, if there is a possibility your certificate
(read key-pair) has been compromised (so it con be compromised
again...) either if you are not sure about it, than you should
revoke it...

So if we do not keep track on the CSLs about the suspension of
non-revoked certificates is because them are to be trusted.

> May be two years later someone claims money from me, based
> on a digital signature produced during that exact period of
> time. If you removed the entry from the CSL, you'll not be
> able to prove that it was not you that signed that document.
> 
> Do you agree?

I do understand your point of view, but how to solve problems
related to the CSL's length ?? And, moreover, how to be sure
your certificate is subject to attacks only in suspension times ??
Once a key/pair has been compromised (or possibily compromised)
it should not, to me, being trusted any more.

What do you think about this ???

C'you,

	Massimiliano Pala (madwolf@openca.org)

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