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Re: KeyNote draft available

At 11:07 PM -0800 3/13/98, Matt Blaze wrote:
>Yes, that's correct.  But a credential that doesn't want to allow
>deligation can test that the value of $action_signers is the same
>as the key being authorized.  (This is admitedly a bit subtle, but
>seems clearner than including an explict mechanism for this.  If
>people insist, we could also include some kind of $cert_depth
>magic variable that gives the "distance" from the action_signers.
>But I'd have to think about the implications of doing this).

This does not prevent delegation by CAs, though, does it?  (Just trying
to clarify KeyNote semantics, ignoring the question of whether it is a
good idea to try to prevent such delegation.)

I authorize a CA like this:

        VERSION: 1
        SIGNER: Policy
        KEY-PREDICATE: dsa-sha1-pkcsX:6:def456
        TRUST-PREDICATE: (($app_domain="RFC822-EMAIL") &&
                          ($address ~= "^.*@research.att.com$"))

Now key def456 is an authorized CA within research.att.com.  But it
can delegate that authority (avoiding the T word in deference to Ed
Gerck...) with:

        VERSION: 1
        SIGNER: dsa-sha1-pkcsX:6:def456
        KEY-PREDICATE: rsa-sha1-pkcsX:6:123aaa
        TRUST-PREDICATE: (($app_domain="RFC822-EMAIL") &&
                          ($address ~= "^.*@research.att.com$"))

Your idea of testing $action_signers in the policy credential won't work
here, because typically $action_signers is the end-user key, not the CA
key.  So is it true that in this case there is no control over delegation?