CDR: RE: Public Key Infrastructure: An Artifact...

[Ray Dillinger]

On Mon, 20 Nov 2000 cgripp at axcelerant.com wrote:

>So what is the acceptable threshold of errors?  1 in a 1000000?  What if
>that 1 is the invalid certificate that allows your bank account to be
>compromised.  CA's should either be 100% or 0% trustworthy.  I do agree that
>there needs to be a protocol to allow CA's to compare databases of
>certificates for mismatches etc that might reveal an attempt at publishing a
>fraudulent certificate.
>
>Gripp


For a CA, I'd say 1 in 10^7 requests, tops, would be an 
acceptable rate of getting spoofed.  But if it were for a 
transaction I was really paranoid about, I might require 
an error rate of 1 in 10^10 or less. Modulo standard 
statistical methods regarding sample sizes, of course -- 
a new CA that's never been spoofed but has only served 
10^8 requests, should be regarded as a hell of a lot less 
reliable than a cert that's gotten spoofed 1000 times out 
of 10^11 requests, just because of sample sizes and number 
of significant figures involved.  

But my point is we don't even have a protocol for swapping 
and updating information about CA's reliability rates, so 
there's no way to even *assess* the reliability of our current 
CA's.  We just assume that they are trustworthy, and sometimes 
we are wrong.  They don't actually check much before they issue 
a cert.  Also, they don't really have a way of revoking their 
certs, so once they realize they've been spoofed they can't 
really correct it very easily -- the spoofing site can go on 
presenting its spoofed cert for a full year in most cases before 
it expires and if the client doesn't contact the CA's keyserver 
directly the client will never know.

I agree with you that CA's should be 100 percent trustworthy. 
Pigs should be able to fly, too. 

				Bear