Authentication apparatus using visual cryptography and method thereof

An authentication apparatus using visual cryptography, the apparatus comprising:

• a communication module configured to receive, from an authentication server, a key image obtained by dividing, by an authentication server, an original image including a user's individual cryptography string generated by the authentication server such that the key image contains only a portion of the user's individual cryptography string, and transmit a user authentication request signal to the authentication server;
• an image processing module configured to receive an encrypted image displayed on a display device from a camera after transmitting the user authentication request signal, extract an encrypted area from the received encrypted image by detecting corners and edges included in the encrypted image using an edge detection algorithm including Laplacian masking, color detection, and color change detection, and convert the extracted encrypted area in such a manner as to correspond to the key image to overlay the converted encrypted area with the key image pre-stored in a smart terminal;
• and
• a display module configured to display an authentication code shown in an area where the encrypted area is overlaid with the key image,
• wherein the image processing module includes:
• a border detection unit configured to extract the encrypted area by detecting slope, rotation, and warping of the detected corners and edges, calibrate the slope, the rotation, and the warping of the detected corners and edges into slope, rotation, and warping of the key image, and detect calibrated corners and edges in the encrypted image input from the camera according to a result of the calibration;
• and
• an encrypted area extracting unit configured to connect all of the calibrated edges and corners, and extract only an inner area of the connected corners and edges as an encryption area by filtering an outer area of the connected edges and corners
• wherein the communication module, the image processing module, the display module, the border detection unit, and the encrypted area extracting unit are each implemented via at least one processor.

An authentication system using visual cryptography, the system comprising:

• an authentication server configured to generate a user's individual cryptography string, divide an original image including the generated cryptography string to generate an encrypted image and a key image containing only a portion of the generated cryptography string, and transmit the generated key image to a smart terminal owned by a user and the encrypted image to a display device when receiving an authentication request;
• the display device configured to display the encrypted image received from the authentication server;
• and
• the smart terminal configured to store the key image received by the authentication server, extract an encrypted area from the encrypted image when the encrypted image displayed on the display device is input via a camera by detecting corners and edges included in the encrypted image using an edge detection algorithm including Laplacian masking, color detection, and color change detection, and display an authentication code obtained by overlaying the extracted encrypted area with the key image,
• wherein the smart terminal is further configured to:
• detect slope, rotation, and warping of the detected corners and edges;
• calibrate the slope, the rotation, and the warping of the detected corners and edges into slope, rotation, and warping of the key image;
• detect calibrated corners and edges in the encrypted image input from the camera according to a result of the calibration;
• connect all of the calibrated edges and corners;
• and
• extract only an inner area of the connected corners and edges as an encryption area by filtering an outer area of the connected edges and corners.