InCommon metadata support

["Cantor, Scott" <>]

I wonder if there's some creative trick one could use whereby periodically a 
test would be run that served up an invalid signed metadata instance 
containing something that would be externally noticeable as having been 
accepted.

Nasty trick, and hard to do with a production system since anything 
externally observable would likely break actual use, but it's an interesting 
idea. Certainly it's possible if you consider a federated app, where the 
"broken" IdP case wouldn't be a real IdP, but for siloed apps, it's much 
harder.

But given that almost no siloed app does verify a signature, and likely they 
never will, maybe that's an interesting requirement to add to a future R&S 
spec and focus on those cases.

Of course, IdPs would also be subject to this.

-- Scott