1. A method comprising: selecting a corresponding visual image for each of a plurality of values in a user identifier; generating a corresponding random representation for each of the plurality of values in the user identifier, each random representation including a unique string of random characters; generating a corresponding random image name for each of the visual images selected for the plurality of values in the user identifier, each random image name including a unique sequence of random characters; for each of the plurality of values, linking the corresponding visual image and the corresponding random image name; and arranging the visual images for presentation to a user during authentication of the user.