A Shoulder-Surfing Resistant Colour Image-based Authentication Method Using Human Vision Perception with Spatial Frequency

Superimposing the high and low spatial frequencies of two different images allows different image interpretations, depending on the viewing distance between the viewer and the image. Previous works used this technique to produce greyscale keypads for PIN entry to prevent shoulder-surfing. Nevertheless, implementation in colour keypads would preserve the underlying look and feel of most applications which are in colour. Thus, the proposed method uses superimposition to produce hybrid image keypads in colour. From user testing and simulated shoulder surfing attacks, it was shown that the proposed method had a low error rate of 3.57% for user logins while none of the shoulder surfing attacks were successful.