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Re: Countersignature within CMS

1998-07-02 09:34:44
A countersignature can be created without the countersigner knowing the
original content. The recipient who is validating the countersignature has
no way of knowing if the signature that was countersigned is valid without
checking that signature as well. Thus, a recipient who can validate a
countersignature but cannot validate the original signature must not infer
that the content that was signed has not been modified, and must not infer
that the original signer actually had access to the content.

Shouldn't the last sentence read "..., and must not infer that the counter
signer actually had access to the content."? Or, are you thinking about a
scenario where a counter signature is bound to another counter signature?

Er, yes. Your changes is what I ment.

I still question the usefulness of a counter signature.

It allows for the countersigner to say "I saw this signature and assure the
recipient that the signature I saw was xyz." It is not meant to say anything
about what the signature was over, but that the signature arrived to the
recipient unmodified. It also allows the countersigner to toss in lots of
interesting attributes about the original signature.

--Paul Hoffman, Director
--Internet Mail Consortium

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