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 the CAPTCHA Problem -- HIPs Within Security Systems -- How Much Assurance Does a PIN Provide? -- Phish and HIPs: Human Interactive Proofs to Detect Phishing Attacks.