A new way of generating grid-scroll chaos and its application to biometric encryption

A new circuit design is proposed for generating grid-scroll chaos in the phase plane by using a second-order linear system with a control of double-hysteresis series. The double-hysteresis series is constructed in a systematic way by using the basic double-hysteresis building blocks. With the proposed scheme, the number of scrolls can be arbitrarily assigned, and the multi-scroll chaotic attractors can be placed anywhere and can cover any chosen area in the phase plane. The grid-scroll chaotic attractor is applied to biometric (fingerprint image) authentication. In this application, a two-dimensional (2D) discrete chaotic image is created from these grid-scroll chaotic attractors. Some of the parameters of the 2D chaotic image are extracted from the stable global structure of fingerprint image, and used to derive the encryption key at a terminal. Decryption, minutiae extraction and matching are fulfilled at the central server.