What about when the CA signing key is stolen, factored, or otherwise falls into the wrong hands, thereby possibly making every signature made by the CA worthless, or at least questionable?
I assume liability will be based on the CA's efforts to ensure the integrity of the signatures it makes (and therefore the confidentiality of the secret key components), but what constitutes due diligence? As we all know, security measures cover a very wide range and can reach ridiculous proportions on both ends of the spectrum... How much security will be 'enough' from a legal standpoint...?
an excellent point, and one that i'd not seriously considered until i saw your post. given today's legal climate, assuring the confidentiality of a ca's key would be pretty expensive. i suppose burning cd-roms with all transactions would help to document all transactions, but would not be definitive as far as the signatures go. any document signed with the key would really have to be considered valid if the signature itself is to really mean anything in a legal sense. if one were to allege that a signature is not valid, even though it checked out cryptologically, how could one defend against a charge that the secret key had been compromised. you cannot prove a negative. obviously, ianal, but i would think it would be reasonably easy to convince at least one jury member that there is a reasonable dought that the key had been compromised. then again, it might be similar to a claim that a signature has been forged. i think there could be a danger of allowing the confidence in a given piece of crypto to unduly influence a jury of a document's authenticity when the key _had_ been compromised. the 'gee wiz' factor could be fairly significant among juries. given statements like 'you could take all the computers on the planet and let them crunch on it for a billion years would be needed', a jury might miss issues of security. fwiw, my 2 cents... ********************************************* * / Only God can see the whole * * O[%\%\%{<>===========================- * * \ Mandlebrot Set at Once! * * amp * * <0003701548@mcimail.com> * * <alan.pugh@internetmci.com> * ********************************************* Key fingerprint = A7 97 70 0F E2 5B 95 7C DB 7C 2B BF 0F E1 69 1D