Patent ID: 8918849

Claim:
A method for generating a recipient-specific credential based on a user's secret using a computing device of a user, the method comprising: receiving an image-based challenge and associated mapping data from an external server; providing the image-based challenge for presentation to the user on an electronic display, the image-based challenge comprising a spatial arrangement of a set of perceptually obscured symbols; accepting a response entered by the user via an input device and determined by the user based on the user's secret and the challenge, the response being based on a sequence of locations in the spatial arrangement; determining an identifier of the recipient; accessing from a data storage a user-specific predetermined random number; applying a computer-implemented credential-generating procedure to combine the mapping data, the response from the user, the identifier for the recipient, and the user-specific predetermined random number to form the recipient-specific credential without exposing the user's secret, including combining the mapping data with the response from the user to determine a mapped response and preventing disclosure of the user's secret internally on the computing device of the user; and providing the recipient-specific credential for transmission to the recipient without providing information sufficient to determine the user's secret from the transmission.