Abstract: The present invention relates to a method for authenticating a user within a communications system. The method includes a portable computing device which captures a graphical counter-token; merges the graphical counter-token and a user token to generate an image revealing a visual key within the merged tokens; and displays the image to the user on the portable device. The graphical counter-token is initially generated by a server utilising the user token and the key. A system for authenticating a user is also disclosed.

Abstract: A device is described for the hiding and subsequent recovery of visual information. The device comprises two or more tokens (1), each containing a mask (2,3) of coloured pixels (4), are overlaid (5), so that when the pixels are aligned, hidden information, invisible in the individual tokens. The hidden information consists of one or more recognisable alphabetic, numerical or pictorial characters (6). During token overlay and alignment, the information becomes recognisable because it is made up of pixels whose colour is differentiated from the other pixels in the overlay. The information is hidden by adding pixels of certain colours. When the tokens are overlaid and the pixels aligned, the added pixels are effectively subtracted, revealing the hidden information. The tokens may be printed on various media, or may be displayed on an electronic device.

Abstract: A device is described for the hiding and subsequent recovery of visual information. The device comprises two or more tokens (1), each containing a mask (2,3) of coloured pixels (4), are overlaid (5), so that when the pixels are aligned, hidden information, invisible in the individual tokens. The hidden information consists of one or more recognisable alphabetic, numerical or pictorial characters (6). During token overlay and alignment, the information becomes recognisable because it is made up of pixels whose colour is differentiated from the other pixels in the overlay. The information is hidden by adding pixels of certain colours. When the tokens are overlaid and the pixels aligned, the added pixels are effectively subtracted, revealing the hidden information. The tokens may be printed on various media, or may be displayed on an electronic device.