Biometric image authentication using watermarking

In this paper, we propose an invertible authentication watermarking algorithm which can detect block-wise malicious manipulations in biometric images. Our method uses an invertible watermark that can also detect manipulated area simultaneously. Virtually all watermarking schemes introduce a small amount of irrecoverable distortion in original biometric images. But our new method is invertible in the sense that, if the data is deemed authentic, distortion due to authentication can be removed if it becomes necessary to obtain the original biometric image. In our method two watermarks are embedded into biometric image. The first one is based on the conventional method which can completely remove the distortion due to authentication if the data is deemed authentic. The second one can detect the block-wise malicious manipulation using the Cyclic Redundancy Check (CRC) concept in the image block. Our proposed method can classify a test image into two types; authentic, and manipulated. Also, this technique provides cryptographic strength when verifying image integrity because the probability of making an undetectable modification to the image can be directly related to a secure cryptographic element, such as a hash function.