Patent ID: 8739276

Claim:
One or more computer-readable storage media that store computer-executable instructions to generate human interaction proofs, wherein the computer-executable instructions, when executed by a computer, cause the computer to perform acts comprising: receiving, in a captcha specification language, a definition of a human interaction proof scheme that defines: an alphabet from which multiple symbols are to be selected as answers to a human interaction proof, multiple complications that are selectable for use in generation of the human interaction proof, and multiple values that individually defines extents to which respective complications of the multiple complications are to be applied to the symbols of the alphabet, wherein a first value of the multiple values defines a fixed extent for application of a first complication of the multiple complications, and wherein a second value of the multiple values defines a random extent for application of a second complication of the multiple complications; generating a graphical representation of the human interaction proof in accordance with the alphabet and the multiple complications by applying at least the first complication by the fixed extent to a first symbol and applying the second complication by the random extent to a second symbol; and employing the graphical representation to selectively control access to a service.