Paul Hoffman wrote, On 2008-06-09 09:41: > At 11:22 AM +0200 6/9/08, Jean-Marc Desperrier wrote:
>> Aren't the people who send their credit card number on an https >> connexion where the private key of the server is public knowledge >> already screwed ? > > Yes, of course. The question for this thread is: who is responsible > for each screwedness? I beg to differ. The question is: for what is the CA responsible? It is for assuring the certified binding of name and key. When that binding has no more assurances, the certificate becomes a false statement of assurance. > However, given that a CA cannot know whether or not a domain has been > compromised, A CA can know that a key has been compromised. Whether an actual exploit of that compromise exists for any user at any specific time may be unknowable, but is not the only factor in determining the CA's responsibility to the relying parties. > a CA that tries to save the customer by revoking the possibly-compromised > domain's keys is overstepping its responsibility. The keys in question are not "possibly compromised". They are compromised. Period. Only the degree to which the compromised key has been exploited may be unknown. A CA who informs it relying parties that it can no longer assure the binding that it once certified is fulfilling its responsibility, not exceeding it. >> Isn't the entity the users trust when they see a certificate foremost >> the CA that emitted it ? > > Yes. That trust hasn't been broken, unless the CA said to the users > "and we will revoke the certificate if we suspect that the key could > likely be compromised". The keys ARE compromised. A CA who refuses to timely revoke a cert with a known compromised key abrogates any public trust. > They keys are not "broken", they are "trivial to break if an attacker > wants to". They are compromised. There is no reason to believe that only the named subject holds the corresponding private key, (since I also hold it :). > That's an important difference, and one that needs to be > made in any warning we give to a user. It's the difference between "Your drawer in the bank vault has been robbed" and "the bank vault door lock is now broken and the door is wide open". Both situations demand action. _______________________________________________ dev-tech-crypto mailing list dev-tech-crypto@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-tech-crypto
