CAPTCHAs and Performance Analysis -- Building Segmentation Based Human-Friendly Human Interaction Proofs (HIPs) -- A Highly Legible CAPTCHA That Resists Segmentation Attacks -- Visual CAPTCHA with Handwritten Image Analysis -- Characters or Faces: A User Study on Ease of Use for HIPs -- HIP Architectures -- Collaborative Filtering CAPTCHAs -- CAPTCHA Generation as a Web Service -- Leveraging th…