Robot CA at toehold.com

[Per Tunedal]

At 17:03 2002-12-05 -0500, you wrote:
 >On Thu, Dec 05, 2002 at 03:34:54PM -0600, Kyle Hasselbacher wrote:

 >>
 >> All this gives us is a binding between a key and an email address.
 >
 >Agreed.
 >
 >> It makes it safer to use that key when sending mail to that address.
 >
 >Agreed.
 >
 >> It's better than using an untrusted key because you can be more sure
 >> it will work and not require the user to backtrack somehow.
 >
 >Agreed, BUT: in the real world, there is no way to guarantee that
 >every key holder will get this email checking signature.  Therefore,
 >there will be some keys with, and some keys without.  Therefore we
 >must handle both cases.  My thinking is that since we have to handle
 >both cases, there is no benefit derived here.
 >
 >If Granny gets Alice's key, and it doesn't have the signature, her
 >only proper course of action is to use the key untrusted since she
 >doesn't know if Alice has had her key validated or not.
 >
 >I think that an email checking robot could be very useful in closed
 >communities - say, the Debian folks, a university, or even a
 >particular ISP or email provider (the "hotmail.com" robot?).  In a
 >closed community, Granny CAN say "if the key isn't signed, I won't use
 >it".  This is why some companies have a "official key signer" key, and
 >the Debian folks have their own authentication scheme.
 >
 >Doing this for all email across communities has no benefit that can't
 >also be gotten via smart code on Granny's computer, and since we need
 >that smart code anyway for those keys that aren't email-validated, why
 >do the work twice?
 >
 >> >We've discussed one reason thus far: it makes it a lot harder for
 >> >Mallory to perform a DoS attack against by publishing a bogus "Alice"
 >> >key.  Still, remember that Granny's software can defeat the same
 >> >attack by just encrypting to all "Alices".
 >>
 >> If Alice doesn't have a key at all, Granny's software hasn't defeated the
 >> attack.  It's also not defeated if Granny has a bogus key but not the real
 >> one (though this seems less likely).
 >
 >If Alice doesn't have a key at all, then all schemes fail.  Let's
 >presume at least that Granny can get some of Alice's keys.
 >
 >If Alice has multiple keys, and one is validated, then Granny
 >encrypted to the validated one.
 >
 >If Alice has multiple keys, none validated, Granny encrypts to all
 >Granny can get.
 >
 >Now, since Granny has no way to know if Alice has gotten her key
 >validated, Granny can't tell the difference from the first case and
 >the second case where she was unable to get the validated key.  This
 >is the case for all non-closed communities.
 >
 >(Yes, I know Alice could tell Granny to look for the email validation
 >signature, but if Alice can communicate securely with Granny, then
 >Alice could just read her a key fingerprint as well).
 >
 >David

No, Granny will NEVER read any fingerprints!
And Alice might tell Granny to use the robot, (if it's not done 
automatically by her software). And ask her about which e-mail adress she uses.

NB This can be implied TODAY with GPG and GPG Relay + key submission to the 
CA-robot.

In the near future it can be done invisibly by e-mail software!

Per Tunedal