Subject: Re: [pkix] Recommended Language for a Security Issue

From: Stephen Kent <[email-masked]>
Date: Mon, 2 May 2011 08:11:28 -0400

At 5:52 PM -0700 4/19/11, Henry B. Hotz wrote:
>I still don't think I have this right.  My latest iteration on the 
>warning label to go in the draft-hotz-kx509 (not yet submitted) is:
>
>    The public key in the request is sent in the clear, and without any
>    guarantees that the requestor actually possesses the corresponding
>    private key.  Therefore the only appropriate uses of the returned
>    certificate are those where the subsequent use independently
>    guarantees that the user possesses the private key.  In particular
>    the returned certificate MUST NOT be used for durable signatures of
>    application data unless the application's use is appropriately
>    structured, or the identity of the signer is not important.
>
>In less formal terms: the public key in the request could be sniffed 
>by someone and they could send their own request with the same 
>public key.  Then there would exist two certs whose keys would match 
>something signed by the first requestor.  That might support a form 
>of plagiarism.

The last sentence is too narrow, in the general PKI case, although it 
might be less of an issue in the Kerberos case. I suggest you look at 
the literature re why proof-of-possesion is an important aspect of 
cert
request protocols.

Steve