phishing the DS protocol

[Tom Scavo <trscavo@gmail.com>]

The Identity Provider Discovery Service Protocol and Profile talks
about the dangers of phishing attacks and how metadata can mitigate
this threat. However, it stops short of specifying that the DS MUST
ensure by some means (metadata or otherwise) that the location
specified in the return parameter is in fact associated with the
requester given by the entityID parameter. Am I missing something?

Thanks,
Tom