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  1. 1. V.Deepthi, Dr.Sandeep.V.M / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1308-1311 Simple Tool For Efficient Image Cryptography V.DEEPTHI1 Dr.SANDEEP.V.M2 ECE Dept., JPNCE, Mahabubnagar, Andhra Pradesh1 HOD & Prof., ECE Dept., JPNCE, Mahabubnagar, Andhra Pradesh2 and only if the key is known. The resultingAbstract- encrypted Secure transmission and storage ofcolor images is gaining importance in recentyears due to the proliferation of multimedia image is found to be fully distorted, resulting innetwork applications. Image encryption increasing the robustness of the proposed work.techniques scrambled the pixels of the image The remainder of this paper organized as follows.and decrease the correlation among the pixels, In section 3, we describe our proposedto get the encrypted image. In this paper we cryptosystem. We validate the proposed methodpropose a new effective and simple method for through experiments and finally we conclude inimage encryption which employs magnitude and section 4.phase manipulation using cross-over andmutation approaches for encrypting color II. BACKGROUNDimages. The proposed approach is very sensitive In this section we give an overview ofto any slight changes in the secret key values, different image encryption and decryptionmaking it very different to decrypt heuristically. methods. Literature suggests many techniques for encryption and decryption.Keywords- cross-over, cipher, cryptography,decryption, encryption, mutation. 2.1. DIGITAL SIGNATUREI. INTRODUCTION A. Sinha and K.Singh [13] have proposed The rapid growth of computer networks, a technique to encrypt an image for secure imageinformation security is an increasingly important transmission. Before transmission digital signatureproblem popular application of multimedia of original image is embedded to the encodedtechnology and increasingly transmission ability of version. Encoding is done by using error controlnetwork gradually lead us to acquired information code. At the receiver end after decryption digitaldirectly and clearly through images [6]. Hence signature is used to authenticity of the imageimage security has become a critical and imperative without the knowledge of the specific error controlissue [7]. Image encryption techniques try to code it is very difficult to obtain the original image.convert an image to another image that is hard to The dimensions of the image also changes due tounderstand; to keep the image confidential between the added redundancy increment in the size of theusers, in other word, it is essential that nobody image due to added redundancy in the disadvantagecould get to know the content without a key for of this algorithm.decryption [1][8]. Many image encryptionmethods have been proposed but some of them 2.2 Linear independence scheme and logistichave been known to be insecure [12], so we always map methodin need to develop more and more secure image Hazem Mohammad Al-Najjar [3]encryption techniques. Traditional data encryption proposed encryption method based on logistic maptechniques can be divided into two categories method. In this method by applying XOR operationwhich are used individually or in combination in between two neighbor pixels it will creates a linearevery cryptographic algorithm [2]. Image independence relationship. Logistic map method isencryption approaches fall into two broad developed encryption keys for images by shufflingcategories: spatial domain methods [9] and the pixel positions.frequency domain methods [10] [14]. 2.3 Chaotic sequence method:In this paper we present a novel image encryption Yi Kai-Xiang and Sun Xiang [5] give anscheme for magnitude and phase manipulations image encryption algorithm based on chaoticusing crossover and mutation techniques these sequence the real number value chaotic sequences.techniques are composed with a simple diffusion First, the real number value chaotic sequencesmechanism [13]. The proposed method dealing using the key value is generated. Then it iswith private key cryptosystem in frequency domain dispersed in to symbol matrix and transformationand it can be retrieved from the encrypted image if matrix. Finally the image is encrypted using them in DCT domain. DCT is a lossy data compression technique, image may occur some distortions 1308 | P a g e
  2. 2. V.Deepthi, Dr.Sandeep.V.M / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1308-1311caused by lossy data compression and noise, but scrambled image will be created which can be hardthis method can still correctly decrypt and restore to understand. The process of shuffling is done byoriginal image, and can achieve a high security considering different combinations of componentsdegree. in an image. By reordering the adjacent2.4.Double random phase encoding: components the original image can be encrypted S. Zhang and M. A. Karim [15] have but it is near to the original image. To increase theproposed a new method to encrypt color images security different combinations of re-orderusing existing optical encryption systems for gray- mechanisms are used. Just replacing the pixelscale images. The color images are converted to positions or reordering the neighboring rows andtheir indexed image formats before they are columns is not sufficient for the better imageencoded. In the encoding subsystem, image is encryption so we have to implement a newencoded to stationary white noise with two random algorithm for image encryption and decryption.phase masks, one in the input plane and the other in After reordering process the mutation operation isthe Fourier plane. At the decryption end, the color performed. In this mutation NOT operation isimages are recovered by converting the decrypted applied on the reordered components.indexed images back to their RGB (Red-Green- Disadvantage of this method is the encrypted imageBlue) formats. The proposed single-channel color is easily recognized because the scrambled imageimage encryption method is more compact and components are having the same components as therobust than the multichannel methods. This original image.technique introduces color information to opticalencryption. An RGB color image is converted to an 3.2 Image Encryption and Decryption in FFT:indexed image before it is encrypted using a typical Further improvement of image encryptionoptical security systems. At the decryption end, the a new effective algorithm is introduced inrecovered indexed image is converted back to the frequency domain.FFT is a fast algorithm forRGB image. Since only one channel is needed to discrete Fourier transform. Here in this case FFT isencrypt color images, it reduces the complexity and a secret key between the users for encryption andincreases the reliability of the corresponding decryption of an image. When the fast Fourieroptical color image encryption systems [11]. transform is applied to the original image the components are a combination of real and 2.5 Spatial domain: imaginary parts. The complexity of scrambled The approaches in this category are based image will be increased by adding some more newon direct manipulation of pixels in an image. In this algorithms to encrypted images along with FFT.algorithm the general encryption usually destroysthe correlation among pixels and thus makes the 3.3 Cross-Over Operation:encrypted image incompressible. By using spatial In this section two frequency domaindomain the encryption efficiency is very less. components are taken and combined aboutFrom above discussions we can say that due to the crossover point their by creating two newredundancy, distortions and noise in images may components. The cross-over method is used forreduces the efficiency of encryption levels. To swapping the real and complex parts of the oneovercome these problems the proposed method is component with the real and complex parts of otheruseful. In this method by using the crossover and component, which will result in a change in themutation operations will results in better encryption amplitude and the phase of the new components.efficiency. Reversibility of crossover operation the same indices will be generated and consequently theIII. EFFICIENT AND ROBUST IMAGE crossover effect will be removed and the originalENCRYPTION components will be retrieved again [15]. Before In this paper, we propose a method that applying the crossover operation the image isimproves the encryption efficiency and yet containing the below real and complex values.maintain its simplicity in implementation. The R1=real1, C1=complex1method uses cross-over and then mutation process R2=real2, C2=complex2in frequency domain to achieve a better encryption. After performing the crossover operation on image the resultant components will be formed as follows;3.1Transposition method in frequency method: R1=complex2, C1=real2 Frequency domain gives a better R2=complex1, C2=real1encryption of an image than spatial domain. TheFourier transform of an image can be complex and 3.4 Mutation Operation:hence both the magnitude and the phase functions Mutation technique is introduced toare necessary for the complete reconstruction of an further complicate the encryption. In this methodimage from its Fourier transform. Displacing the NOT operation is performed on the components.component positions in original image the new By applying mutation the resultant components are 1309 | P a g e
  3. 3. V.Deepthi, Dr.Sandeep.V.M / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1308-1311 compliment of an original image which will gives TABLE1 the beneficial encryption results. This mutation Encryption / Decryption efficiency of the function is self invertible proposed method. S.NO Object type Encryption 3.5 Mixture of cross-over and Mutation: efficiency in % Combination of crossover and mutation 1. Animals 96 methods will give better privacy when compared to 2. Human beings 90 the individual methods and also gives the 3. Flowers 75 confidential results. In this section the Mutation 4. Historical 98 method is added along with the crossover technique places for better image encryption in frequency domain. 5. Natural images 84 This simulation will results very nice encryption effects and good robustness. The table shows the number of encrypted images that the viewers were able to visualize and 3.6.RGB model recognize the objects that were in the original In order to improve the privacy of image. The fewer the objects were recognized, the scrambled color images the combination of better will be the encryption process. It can be seen crossover and mutation methods are performed on from the table that the images containing object tri-colors (Red, Green and Blue) of an image. like flowers are very easily recognized. Encryption Ciphering of image by slicing the image into sub complexity in such cases should be increase. images whose dimensions are kept confidential and applied proposed methods to each of these sub V. CONCLUSION & FUTURE WORK: images this will increases the efficiency of an In this paper, a successfully efficient encryption. implementation of encryption scheme is introduced for digital image encryption. This encryption scheme proposed crossover and mutation operation on the frequency domain components of the plain image, therefore changing this components amplitude and phase in order to achieve more confusion and diffusion in the cipher image. Whena) Original image b) Encrypted image c) Decrypted image compared to many commonly used algorithms the proposed algorithm resulted in the best Fig1: The response of Proposed Cryptosystem on a performance. According to the results of our Color Image proposed method, we conclude that the future research will be expanded to increase the efficiency of fewer objects which are recognized by the viewers, by adding some new algorithms along with the proposed method to increase the complexity. References: [1] H. El-din H. Ahmed, M. K Hamdy, and O. a)Original image b)Encrypted original S. Farag Allah, "Encryption quality c)Decrypted image analysis of theRC5 block cipher algorithm for digital images," Optical Engineering, Fig2: Response of proposed method Vol. 45, Issue 10107003, 2006. [2] B. A. Forouzan, “Traditional Symmetric- IV. Performance evolution: Key Ciphers,” in Introduction to The proposed method is applicable for Cryptography and Network Security, 1st gray-scale images and also for color images. From ed., New Yourk, the McGraw-Hill the above shown encrypted image we can say that Companies, Inc., 2008, ch. 3, sec. 1,pp. the regions of the scrambled image are totally 60-61. invisible. [3] Hazem Mohammad Al-Najjar,”Digital Experiments conducted wherein the various Image Encryption Algorithm Based on a encrypted images are shown to a group of 50 Linear Independence Scheme and the people to identify them. The fewer the number of Logistic Map”. people who could identify the object in the image, [4] Ibrahim S I Abuhaiba and Maaly A S the better efficient will be encryption algorithm. Hassan „‟image encryption and decryption using differential evaluation approach in frequency domain”. signal and image 1310 | P a g e
  4. 4. V.Deepthi, Dr.Sandeep.V.M / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1308-1311 processing: An International Journal Authors Information: (SIPIJ) vol.2, No.1, March 2011. [5] Yi Kai-Xiang and Sun Xing et al., “An image encryption algorithm based on chaotic sequences,” Journal of Computer Aided Design and Computer Graphics, Vol. 12, No. 9, 2000, pp. 672-676[6] W. Lee, T. Chen and C. Chieh Lee, "Improvement of an encryption scheme 1.V.Deepthi Pursuing M.Tech(DSCE) from for binary images," Pakistan Journal of JayaPrakash Narayana College of Engineering Information and Technology. Vol. 2, no. B.Tech(ECE) from JayaPrakash Narayana College 2, 2003, pp. 191-200.. of Engineering Currently she is working as [7]. A. Mitra, Y V. Subba Rao, and S. R. M. Assistant Professor at Jayaprakash narayan college Prasnna, "A new image encryption of engineering And has 2 years of Experience in approach using combinational permutation teaching . Her areas of interest include,Image techniques," Journal of computer Science, Processing ,wireless networks, signal processing Vol. 1, no. 1, 2006, p.127.[8] B. Mohammad Ali and J. Aman," Image Encryption Using Block-Based Transformation Algorithm," IAENG Int. Journal of Computer Science, Vol. 35, Issue 1, 2008, pp. 15-23.[9] S. K. Panigrahy, B. Acharya, and D. Jena, “Image Encryption Using Self-Invertible Key Matrix of Hill Cipher Algorithm,” 1st 2. Dr. Sandeep V.M. completed Ph.D in Faculty of International Conference on Advances in Electrical and Electronics Engineering, Sciences, Computing, Chikhli, India, 21-22 from Visveswaraiah Technological University, February 2008. Belgaum, and M.Tech from Gulbarga University[10] S. R. M. Prasanna, Y. V. Subba Rao and and B.Tech from Gulbarga University. His research A. Mitra, “An Image Encryption Method interests are in the areas of Signal and Image with Magnitude and Phase Manipulation Processing, Pattern Recognition, Communication, using Carrier Images,” International Electromagnetics. He is Reviewer for Pattern Journal of Computer Science, Volume 1, Recognition Letters (PRL). He acted as Reviewer Number 2, February 20, 2006 for many International Conferences.He has 24 [11] W. Zeng and S. Lei, “Efficient Frequency years of teaching experience. He is member of Domain Selective Scrambling of Digital LMIST – Life Member Instrument Society of India Video,” IEEE Trans. Multimedia, 2002. (IISc, Bangalore). And he guided more than 100[12] Li. Shujun, and X. Zheng "Cryptanalysis projects at UG level and 35 at PG level.And of a chaotic image encryption method," published more than 10 papers in international Inst. of Image Process, Xian Jiaotong journals and 9 Conference Proceedings. Univ., Shaanxi, This paper appears in: Circuits and Systems, ISCAS 2002. IEEE International Symposium on Publication Date: 2002, Vol. 2, 2002, pp. 708-711. [13] A. Sinha, K. Singh, “A technique for image encryption using digital signature,” Optics Communications, 2003, pp. 1-6 [14] W. Zeng and S. Lei, “Efficient Frequency Domain Selective Scrambling of Digital Video,” IEEE Trans. Multimedia, 2002. [15] S. Zhang and M. A. Karim, “Color image encryption using double random phase encoding,” Microwave and optical technology letters, Vol. 21, No. 5, June 5 1999, pp. 318-322. 1311 | P a g e