>> Yup, from the perspective of a significant proportion of modern >> websites, MIME sniffing would be almost certainly a disaster. > > I'm not suggesting sniffing, I'm suggesting having a single well-defined > algorithm with well-defined fixed signatures. > > For formats that don't have signatures, this doesn't work, obviously.
We probably can't support a well-defined algorithm for detecting documents that have distinctive signatures while safely supporting formats that don't have them (because there is always a possibility that the non-structured format with user-controlled data could be used to forge a signature).