Securing iris images with a robust watermarking algorithm based on discrete cosine transform

With the expanded use of biometric systems, the security of biometric trait is becoming increasingly important. When biometric images are transmitted through insecure channels or stored as a raw data, they become subject to the risk of being stolen, faked and attacked. Hence, it is imperative that robust and reliable means of protection are implemented. Various methods of data protection are available and digital watermarking is one such techniques. This paper presents a new method for protecting the integrity of the iris images using a demographic text as a watermark. The watermark text is embedded in the middle band frequency region of the iris image by interchanging three middle band coefficients pairs of the Discrete Cosine Transform (DCT). Experimental results show that exchanging more than one pair will make middle band scheme more robust against malicious attack along with making it resistant to image manipulation such as compression. The results also illustrate that our watermarking algorithm does not introduce discernible decrease on iris image quality or biometric recognition performance.