Visual CAPTCHAs

This problem deals with visual CAPTCHAs.

a. Describe an example of a real-world visual CAPTCHA not discussed in the text and explain how this CAPTCHA works, that is, explain how a program would generate the CAPTCHA and score the result, and what a human would need to do to pass the test.

b. For the CAPTCHA in part a, what information is available to an attacker?

This problem deals with audio CAPTCHAs.

a. Describe an example of a real-world audio CAPTCHA and explain how this CAPTCHA works, that is, explain how a program would generate the CAPTCHA and score the result, and what a human would need to do to pass the test.

b. For the CAPTCHA in part a, what information is available to an attacker?

Solution: