I agree that asking people to enter a phrase from the advertisement is not going to be a very secure CAPTCHA test because the advertiser is never going to be ab

I agree that asking people to enter a phrase from the advertisement is not going to be a very secure CAPTCHA test because the advertiser is never going to be able to come up with enough different phrases to make a captcha that will be secure against brute force attacks. Also, if they want their dish network ad displayed often (to get more impressions) then again it's basically a static image that is not changing often enough to keep out bots. An alternative could be this: http://www.confidenttechnologies.com/products/confident_CAPTCHA.php http://www.confidenttechnologies.com/products/confident_CAPT... The user is presented with a grid of images. The pictures themselves and their location on the grid change with each session. A website could insert just a few of their own images within the grid, as a way of reinforcing brand recognition without being blatant advertising that forces the user to enter a slogan. For example, if it's a sporting goods website, they could include some images of the items they sell among the stock photos. Because it's a grid of images that changes every time, there would be a huge amount of combinations possible, making it a stronger captcha against brute force attacks from bots.