Focus-based challenge-response authentication

A non-transitory, machine-readable medium comprising a plurality of machine-readable instructions that, when executed by one or more processors, cause the one or more processors to perform a method comprising:

• detecting an access attempt by a user device over a network;
• providing a challenge-response authentication over the network to the user device, wherein the challenge-response authentication includes an image having a plurality of image objects, and wherein the challenge-response authentication is operable to display the image while changing a focal point of the image according to a predetermined timing schedule such that at least one of the plurality of image objects that is in focus is unfocused and at least one of the plurality of image objects that is not in focus is focused;
• receiving, in response to providing the challenge-response authentication, an authentication response from the user device over the network;
• and
• determining whether the authentication response includes an indication of or information about the at least one of the plurality of image objects that is in focus.

A focus-based challenge-response authentication system, comprising:

• means for detecting an access attempt;
• means for providing a challenge-response authentication, wherein the challenge-response authentication includes an image having a plurality of image objects, and wherein the challenge-response authentication includes means for displaying the image while changing a focal point of the image according to a predetermined timing schedule such that at least one of the plurality of image objects that is in focus is unfocused and at least one of the plurality of image objects that is not in focus is focused;
• means for receiving, in response to providing the challenge-response authentication, an authentication response;
• and
• means for determining whether the authentication response includes an indication of or information about the at least one of the plurality of image objects that is in focus.