From the (overly lengthy) Patent Description section: A challenge-response test may include a type of authentication where one party (e.g., security device 240

From the (overly lengthy) Patent Description section: A challenge-response test may include a type of authentication where one party (e.g., security device 240) presents a question (e.g., a “challenge”) and another party (e.g., attacker device 210) is required to provide a valid solution (e.g., a “response”) to be authenticated. An unsolvable challenge-response test may include a challenge-response test that does not have a correct solution and/or a challenge-response test where attacker device 210 may be incapable of providing the correct solution (e.g., when the correct solution includes a character that may not be typed using a standard keyboard, etc.). In some implementations, security device 240 may generate the unsolvable challenge-response test in the form of an unsolvable CAPTCHA. In some implementations, security device 240 may generate the unsolvable CAPTCHA using one or more construction techniques that are designed to block attacker device 210 from sending a request to server device 230 without making attacker device 210, and/or a user of attacker device 210 (e.g., a hacker), aware that attacker device 210 is being blocked (e.g., by security device 240) from sending the request to server device 230.