Graphical user authentication(GUA) uses graphical passwords. The procedures for graphical authentication work with recognition techniques or with image sequences whose sequence is fixed and must be called up.
Compared to text-based methods, graphical authentication has the advantages that people can remember graphics better than letter- digit combinations and that graphical passwords have a much higher security standard. For many users, choosing an image is much easier than choosing a cryptic letter-digit sequence, which usually has to be entered as a password or passphrase. In addition, graphical passwords can provide a higher level of security than letter- and digit-based passwords. Especially since hackers use dictionary entries with classic passwords to gain unauthorized access.
With recognition methods, the user must select the images that he or she specified during registration. The procedure can be improved in that the user clicks on the images in the correct order from a selection of images. The probability of the image combination depends on the number of images displayed and the number of images to be selected. If there are 50 images to choose from and 10 have to be selected in the correct order, this results in '50^10' or over 1 trillion different possibilities.