ISBN 978-93-84468-20-0 Proceedings of 2015 International Conference on Future Computational Technologies (ICFCT 2015) Singapore, March 29-30, 2015, pp. 78-84 Encryption Based Medical Image Watermarking against Signal Processing Attacks Abhilasha Sharma 1 , Mayank Dave 2 , Amit Kumar Singh 1 and S P Ghrera 1 1 Department of Computer Science & Engineering, Jaypee University of Information Technology, Waknaghat, Solan Himachal Pradesh India 2 Department of Computer Engineering, NIT Kurukshetra, Haryana India Abstract: The protection of data is of at most importance in the medical field to boost the telemedicine applications. There is a need of robust and secure mechanism to transfer the medical images over the Internet. The algorithm proposed in this study is the watermarking technique in the transform domain to ensure secure transfer of medical data. Using DWT transformation and substitution method, we embed the watermark into the cover image and the watermarked image is then encrypted by using the symmetric stream cipher techniques. Performace of the proposed algorithm is analyzed against various signal processing attacks like compression, filtering, noise and histogram equalization and desired outcome is obtained without much degradation in extracted watermark and watermarked image quality. Keywords: Watermarking, DWT, Robustness, Medical images, Imperceptibility 1. Introduction The growing technology nowadays offers substantial new opportunities for sharing and transmission of the valuable digital data such as images, audio and video [1].The Internet and electronic media has improved medical facilities in the form of tele-medicine, tele-diagnosis, tele-consultancy etc. [2]. The digital revolution has boosted the sharing of medical images and confidential medical data among the health care professionals and healthcare institutions, which has led to the requirement of the safety issues concerned with the legal and ethical aspects specific to the medical domain. The ease by which digital data can be duplicated and distributed has raised the need of the effective content and copyright protection mechanisms [3]. With these evolutionary technologies, the security of the medical images and medical records has attracted great attention. The digital handling of such information requires a systematic content validation, copyright management and content protection. The ease of transmitting and sharing the medical data increases the security issues in terms of confidentiality, availability and reliability [4]. The traditional cryptographic techniques provide medical data protection and authentication. Some techniques also provide the confidentiality, integrity and non-repudiation [5-9]. However, only the cryptographic solutions are not sufficient to handle all facets of security in the medical domain [10]. The digital imaging and communication in medicine (DICOM) standards make exchange of medical images more convenient, quicker and dependable. The DICOM files are switched between the entities in a fixed way. Nevertheless, if the cryptanalyst is able to obtain the information regarding key and forms in the encrypted data, the data is no longer protected [11-14]. A method to enhance the security of the medical images is the digital image watermarking [15]. These methods provide the complementary security for the medical images to share them over the open network channels [16, 17]. It is the process of embedding data, called a watermark, to the