On 18/12/08 13:20, Anders Rundgren wrote:
Kyle,
I fully agree with your conclusions.
IMO a signature's primary function is to provide a mark of authenticity
to something. If the signature is associated with an unknown signer
the value of the signature becomes rather limited.
The Qualified Certificate concept is based on the strange idea that
because the CA is liable to very high amounts of money, you can
"trust" such signatures and thus do advanced business with total
strangers.
This is based on the monetary view of reliability, in that it is only
worth what you can get for it. Standard finance principle. If there is
nothing, it is worth nothing; if you can do harm X then it is worth X,
potentially; if you can get Y then it is worth Y, potentially.
(Case in point about a year ago, oh how soon we forget, is S&P, Moodys
and the rating agencies.)
This I find to be quite a valid view, and it is widely used in the
corporate and finance world, c.f., NPV, MTM, CAPM, where numbers are
called for. Although it certainly doesn't explain all of contracts &
agreement behaviour.
Whether you can take that monetary number and relate that to "trust" is
a whole other discussion...
And, we probably agree that the end result with Qualified certificates
is likely to show the same as with non-QCs, in that the resultant value
to relying party in objective monetary terms is zero. (In other posts I
have expressed the opinion that the expected liability is zero, which is
another way of saying it.)
What the designers of QC didn't think of is that anybody
can get a QC without being checked to be a good payer, dependable
vendor, etc. If there is discomfort in a business relation, the CA has
no means to rectify things making the value of the high liability very limited.
IF people started to believe that QC actually works as described we would
soon be in a very bad position since a single disgruntled employee could
send "fully authorized" POs all-over-the-map.
Yes. But companies and people are generally smarter than that. They
know the monetary value is zero, and non-monetarised values are limited
to the regulated needs, in general.
PKIX took this to another extreme by publishing an informational standard
for liability with is one of the most ridiculous things I have ever seen
http://www.ietf.org/rfc/rfc4059.txt
since it doesn't deal with accumulation!!! The motive behind this RFC
was "to increase the acceptance of certificates" :-)
Perhaps you could explain what you mean by accumulation? I skimmed
through that document, and had my own qualms.
Q: does any CA actually use that extension? Does any code display the
extension?
I note that it "must be non-critical" which I find amusing :)
iang
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