Embodiments described herein relate to a device operable to process input for a picture password for proof of knowledge. In some embodiments, the device includes a display, an input subsystem, processor(s), and memory containing instructions executable by the processor(s) such that the device is operative to display, on the display of the device, an image for the picture password proof of knowledge. The image is associated with an overlaid grid comprising a plurality of elements, and each element corresponds to a distinct area of the image. The device is further operative to, determine an offset to be used and, in response to receiving an input via the input subsystem at a first location of the display, highlight an element of the overlaid grid at a second location on the first image on the display. The second location is offset from the first location by the offset.