On Tuesday 01 August 2006 09:57, John Levine wrote:
> >> In my book it's the same as A signed by A.  The only concern I would
> >> have is if B added content, what to do about that, I'm not sure.
>
> I'd appreciate a concrete example where B adds and signs content without
> breaking A's signature.
>
> There's a few scenarios that have come up:
>
> * The first signature has l= and B adds stuff at the end.
>
> * The first signature didn't have MIME headers and B adds them,
> perhaps making a lot of the original message invisible in a newly
> defined MIME part.
>
> Note that these two are easy to defend against: always sign MIME headers,
> even if there aren't any, and don't use l=.
>
> If people think there are other scenarios where a second signer can
> make signficant changes to a message without breaking an existing
> signature, we have worse problems than SSP.
>
No, those are the things I was thinking about.  Probably not a significant 
issue, but I thought it worth mentioning.

Scott K
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