At 1:43 AM +0200 6/20/07, A. Pagaltzis wrote:
* Paul Hoffman <phoffman@xxxxxxx> [2007-06-19 21:40]:The method for a server to indicate to a third party whether or not the client signed an Entry Document is by including the client's signature in the published entry, even though that signature is likely to be invalid.I strongly disagree with this. As a consumer, I have no possible way to know whether an invalid signature is there because * the publishing client included it * the server made up a signature to feign signing by the client * a third party tampered with the entry between the server and me Therefore as a consumer I would never ever assume that an invalid signature meant anything else than that the signature on this entry is not valid.
Fully agree so far.
Encouraging servers
Stop right there. Nothing in the quoted text *encourages* anyone. We said that there was a method, which is completely true. We also said that this is "the" method, which is also completely true (we didn't create another method). That is a far cry from encouragement.
If the server is not, though, then it really should strip the signature if it knows it has invalidated it. Note that my proposed text said "strongly encouraged", not "SHOULD". After all, it is not an interop concern, nor do I desire to dictate server behaviour.
The WG has gone out of its way to put as few restrictions on servers as possible, and to minimize the number of "encouragements" (much less strong encouragements). I took that earlier direction to heart in the above paragraph.
If the WG wants to make a strong encouragement here, that's fine, but we do so against our earlier trend.
However, I do think this particular implementation choice makes a lot of sense and should be the default choice for server implementors who don't have specific reason to do things otherwise. And I think the spec should nudge them in that direction.
Given that this is the Security Considerations section, we should have a security reason for the nudge. I don't think we have one. There is no security problem with publishing a known-bad signature.