Then there's some much more general concerns about the NIST curves themselve. These concerns come down to that a) we don't really know how they were generated (there are some numbers in the paper that just "appear out of nowhere") and b) that they've been created by the NSA. But there's no concrete proof of any backdooring and it seems relatively implausible, as no method is known that would explain how that backdooring would work. I guess most people familiar with the facts don't believe they are backdoored.
