I don't understand the point of these regulations. Child pornography is already illegal, as is the distribution of it, online or off. Websites hosting child pornography are already fair game to law enforcement.
Requiring all sexually-explicit photography to be accompanied by paperwork to prove it isn't child pornography won't make those sites already hosting child pornography stop. They know it's illegal. The only ones who will comply with the regulations and attempt to assemble paperwork (good luck doing that for images that are over fifty years old) are the people who are already abiding by the law.
Not to mention the fact that there is quite a bit of pornography that is obviously, plainly, clearly of solely adults. Does anyone really think that it's easy to mistake fully-developed adults in their twenties and thirties with underaged (and what exactly age is underage? 16 is the age of consent in my state, does it differ for images? And by place? Is 18 legal? 21?) children? I'm aware that there is a great deal of disgustingly-named "barely legal" smut out there, which it makes sense to require some form of documentation. But all of it? A website catering to the fetish of lesbian women in their fifties has to produce evidence that the women aren't in fact fifteen?
I'd have to say that this stuff seems geared not to stop child pornographers, who are already violating some serious laws and won't suddenly stop because of an additional regulation about paperwork. It seems designed to harrass and make difficulties for any and all adult content providers on the internet.
Of course, all of this comes along with the additional difficulties of legally defining what is pornography, what is sexually suggestive, what is art. Which of the three is a Calvin Klein or Abercrombie advertisement? Is Michelangelo's David pornographic? What about drawings or paintings? Are they held to the same standards as to providing evidence of age, albeit of fictional characters? Or would it matter if the drawing was from life? Is Joe Phillips a child pornographer for his somewhat cartoony artwork of teenagers? Or can he say they're just young-looking twenty-somethings?