A Proposed Hybrid Encryption &Watermarking Algorithm for Digital Color Image M.A.MOHAMED 1 , M.I.FATH ALLAH 2 , L.W.ELBON 3 1) The Dean of the Faculty of Engineering, Mansoura University, Mansoura, Egypt 2) Assistant Professor at Delta Higher Institute for Engineering & Technology, Mansoura, Egypt 3) Engineer in communication labs of the Faculty of Engineering, Mansoura University, Mansoura, Egypt Corresponding author: Third Author (e-mail:lobna.elbon1992@hotmail.com). Abstract— Nowadays, increasing use and distribution of the digital images through multimedia and communication system have been increased. Therefore, the transmitted data can be attacked by unauthorized people. The main considerable challenge in the digital world is maintaining information security. The traditional techniques are unsuitable for the image encryption. Therefore it is necessary to develop the techniques that be able to secure the color images. This paper introduce a hybrid encryption and watermarking for digital color image against the composite attacks. The discrete cosines transform (DCT) and discrete wavelet transform (DWT) transforms have been extensively used in many digital signal processing applications, so DCT and DWT have been applied for image transformation by two methods. Six chaotic maps have been used with different parameters to establish a relation between the data encryption key and watermark. After extensive studies it has been found that the proposed technique has achieved the best performance than that of the traditional ones. Keywords— Discrete Cosine Transform (DCT), Discrete Wavelet Transform (DWT), Inverse Discrete Cosine Transform (IDCT), Inverse Discrete Wavelet Transform (IDWT) I. INTRODUCTION Nowadays, the great spreading and growing of data through the multimedia and communication systems is causing several problematic facets against securing the data. Distribution or sharing data become very easy and does not required complex operations .Therefore it is essential to improve the techniques that protected the data from the unauthorized users[1]. Moreover, encryption and watermarking represent powerful techniques in securing the content. Encryption makes the content indecipherable through a reversible mathematical transformation based on a secret key. Watermarking is a technique of embedding data into a multimedia component such as image, audio or video[2]. In this paper Encryption and watermarking techniques will be presented in which the original color image has been multiplied by two chaotic maps of the same type and with different parameters and initial conditions. After that, DWT or DCT has been utilized to get the encrypted image. The argue is getting high robustness against composite attack .That merged three various attacks together; noise, cropping and rotation. The composite attack could be obliged to encrypted image in two different forms which are; friendly form and hard form. Six chaotic maps have been used ; (i) Chirikov (ii)Chirikovtan (iii) Henon (iv) Ikeda (v) Logistic and (vi) quadratic. The performance of these scheme maps have been studied with comparative of the traditional ones. The next of this paper is organized as follows; section-2 presents survey and related work, section-3 introduces the proposed techniques, section-4 illustrates the simulation results and discussions, and section-5 demonstrates the conclusions. II. RELATED WORKS In 2015 Benrhouma et al. presented a first virgin of an idea of an semi fragile watermarking and encryption scheme for digital images [3]. In 2016 AlShaikh, Muath, et al. proposed an innovative hybrid encryption watermarking scheme to improve the security and ensure the integrity of medical image content[4]. In 2016 Zear et al concentrated a novel method for multiple watermarking based on DWT, DCT and SVD has been presented using Back Propagation Neural Network[5] .In 2017 Kang, Xiao-bing, et al provided a new robust and invisible blind watermarking scheme based on a combination of DCT and SVD in DWT domain has been to improve the imperceptibility and the robustness[6]. In 2018 Loan, Nazir A., et al. reviwed watermark embedding algorithm has been examined for different grayscale and color images[7]. In 2018 Wu, Q. et al. proposed An adaptive and blind audio watermarking algorithm based on chaotic encryption in a hybrid domain to combat various conventional signal-processing attacks[8].In 2019 Thanki, Rohit M., and Ashish M. Kothari proposed a novel hybrid domain image watermarking technique using watermark speech signal[9]. In 2019 Abdulrahman, Ahmed Khaleel et al.provided an efficient DCT- DWT based hybrid image watermarking method for copyright protection of color images[10]. In 2019 Joshi, M. Tech Scholar Namrata proposed novel computerized water checking strategy dependent on whole number wavelet change with quality based order procedure. For the choice of highlight quality utilized RBF work [11]. III. THE PROPOSED TECHNIQUE The main steps of the proposed algorithm will be discussed and illustrated in flow charts in figures (1, 2). First, the original image has been multiplied by the first chaotic map followed by the second one with different initial conditions. More variations have been given by chaotic maps to enhance the performance by varying its parameters and initial conditions. In the second step the DWT as well as DCT has been applied to obtain the encrypted image at the