The article's over three years old. I didn't say that it was currently accurate. Computing power has increased a lot in three years. I was merely pointing out that if CPU consumption really is a potential gating component, then maybe PoW would actually work. In addition, as computing power increases, it's trivial to increase the amount of computing power needed in order to pass the test.


It uses one word for the validation and another for the donation, not necessarily the first and second. It does have no way to validate the unknown word, and only validates against the known word, but as long as the scrambling algorithm keeps ahead of the spammers, and the spammers keep playing catchup, at some point we'll have an OCR system that's better than what we have now. It's intentionally not hack-proof.


I've never had to do this with ReCAPTCHA. I have with other systems. This, combined with your inability to detect CRT flicker, leads me to disbelieve your assertion of perfect vision.


Assuming that the spammer's client had a working javascript interpreter, yes. But, importantly, also assuming that they're also willing to spend several seconds of CPU time per post maxing their CPU. Assuming that Jon's site used to get spam and doesn't now that he's implemented his PoW scheme, it seems that it's at least driven the spammers to gather lower-hanging fruit. I'm inclined to say that once all fruit gains the same height, it won't make a lot of difference, but maybe I'm wrong.