Methods and systems are described for creating irrefutable binding data for a data file. An input sequence of data elements is derived based on information from the data file. A graphical representation of input regions corresponding to the input sequence of data elements is output on a display, superimposed on captured image data including a visible feature of a user associated with the data file. User input of each data element of the input sequence is captured by tracking the visible feature through the corresponding input regions, and the binding data is created from the captured images as the visible feature is tracked through the input regions.