Prasad Reddy P.V.G.D et. al. / International Journal of Engineering Science and Technology Vol. 2(5), 2010, 1060-1065
A Modified Location-Dependent Image Encryption for Mobile Information System Prasad Reddy. P.V.G.D*, K.R.Sudha2 , P Sanyasi Naidu 3 * Department of Computer Science and Systems Engineering, Andhra University, Visakhapatnam, India,
[email protected] 2Department of Electrical Engineering, Andhra University, Visakhapatnam, India,
[email protected] Department of Computer Science and Systems Engineering, GITAM University, Visakhapatnam, India
[email protected], Abstract: The wide spread use of WLAN (Wireless LAN) and the popularity of mobile devices increases the frequency of data transmission among mobile users. In such scenario, a need for Secure Communication arises. Secure communication is possible through encryption of data. A lot of encryption techniques have evolved over time. However, most of the data encryption techniques are location-independent. Data encrypted with such techniques can be decrypted anywhere. The encryption technology cannot restrict the location of data decryption. GPS-based encryption (or geoencryption) is an innovative technique that uses GPS-technology to encode location information into the encryption keys to provide location based security. In this paper a location-dependent approach is proposed for mobile information system. The mobile client transmits a target latitude/longitude coordinate and an LDEA key is obtained for data encryption to information server. The client can only decrypt the ciphertext when the coordinate acquired form GPS receiver matches with the target coordinate. For improved security, a random key (R-key) is incorporated in addition to the LDEA key. The proposed method is applied for images. Keywords - data security, location-based key, mobile security, random generator, permutation 1. Introduction: The dominant trend in telecommunications in recent years is towards mobile communication. The next generation network will extend today’s voice-only mobile networks to multi-service networks, able to carry data and video services alongside the traditional voice services. Wireless communication is the fastest growing segment of communication industry. Wireless became a commercial success in early 1980’s with the introduction of cellular systems. Today wireless has become a critical business tool and a part of everyday life in most developed countries. Applications of wireless range from common appliances that are used everyday, such as cordless phones, pagers, to high frequency applications such as cellular phones. The widespread deployment of cellular phones based on the frequency reuse principle has clearly indicated the need for mobility and convenience. The concept of mobility in application is not only limited to voice transfer over the wireless media, but also data transfer in the form of text , alpha numeric characters and images which include the transfer of credit card information, financial details and other important documents. The basic goal of most cryptographic system is to transmit some data, termed the plaintext, in such a way that it cannot be decoded by unauthorized agents[5][6][7][8][9]. This is done by using a cryptographic key and algorithm to convert the plaintext into encrypted data or cipher text. Only authorized agents should be able to convert the cipher text back to the plaintext. GPS-based encryption (or geo-encryption) is an innovative technique that uses GPS-technology to encode location information into the encryption keys to provide location based security[12][13][14][15]. GPS-based encryption adds another layer of security on top of existing encryption methods by restricting the decryption of a message to a particular location. It can be used with both fixed and mobile. The terms location-based encryption or geo-encryption are used to refer to any method of encryption in which the encrypted information, called cipher text, can be decrypted only at a specified location. If, someone attempts to decrypt the data at another location, the decryption process fails and reveals no details about the original plaintext information. The device performing the decryption determines its location using some type of location sensor such as a GPS receiver. Location-based encryption can be used to ensure that data cannot be decrypted outside a
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Prasad Reddy P.V.G.D et. al. / International Journal of Engineering Science and Technology Vol. 2(5), 2010, 1060-1065 particular facility - for example, the headquarters of a government agency or corporation or an individual's office or home. Alternatively, it may be used to confine access to a broad geographic region. Time as well as space constraints can be placed on the decryption location. Adding security to transmissions uses location-based encryption to limit the area inside which the intended recipient can decrypt messages. The latitude/longitude coordinate of node B is used as the key for the data encryption in LDEA. When the target coordinate is determined, using GPS receiver, for data encryption, the ciphertext can only be decrypted at the expected location. A toleration distance(TD) is designed to overcome the inaccuracy and inconsistent problem of GPS receiver. The sender can also determine the TD and the receiver can decrypt the ciphertext within the range of TD. Denning’s model is effective when the sender of a message knows the recipient’s location L and the time that the recipient will be there, and can be applied especially effectively in situations where the recipient remains stationary in a well-known location. The mobile client transmits a target latitude/longitude coordinate and an LDEA key is obtained for data encryption to information server. The client can only decrypt the ciphertext when the coordinate acquired form GPS receiver matches with the target coordinate. For improved security, a random key (R-key) is incorporated in addition to the LDEA key. In the present paper the objective is to modify the cipher by introducing the concept of key dependent circular rotation. In this the bits are rotated depending upon the R- key after whitening with the LDEA key using the Exclusive – OR operation. 2. Random number generator using quadruple vector: For the generation of the random numbers a quadruple vector is used[7][10]. The quadruple vector T is generated for 44 values i.e for 0-255 ASCII values. T=[0 0 0 0 0 0 0 0 1 1 ……………… 0 0 0 0 1 1 1 1 2 2…………………….. 0 1 2 3 0 1 2 3 0 1 ……………………..3] The recurrence matrix[1][2][3] [4] 0 1 0 A 1 1 0 0 0 1
is used to generate the random sequence for the 0-255 ASCII characters by multiplying r=[ A] *[T] and considering the values to mod 4. The random sequence generated using the formula [40 41 42]*r is generated.[10] 3. Development of the cipher: Consider a plain text represented by P which is represented in the form ---1 P=[Pij] where i=1to n and j=1 to n Let the R-key matrix be defined by ---2 K=[Kij] where i=1 to n and j=1 to n Let the cipher text be denoted by C=[ Cij] where i=1to n and j=1 to n corresponding to the plain text (1) For the sake of convenience the matrices P,K and C are represented as P=[p1 p2 ……pn2] K=[k1 k2 ……kn2] C=[c1 c2 ……cn2] 3.1 Algorithm for generation of R-key and LDEA key: Algorithm: Algorithm for Encryption: { read n,K,P,r Permute(P) For i=1 to n { p=convert(P); X=p LDEA key Interlace(X) C1=Permute(X) C=LRotate(C1) } Write(C) }
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Prasad Reddy P.V.G.D et. al. / International Journal of Engineering Science and Technology Vol. 2(5), 2010, 1060-1065 Algorithm for Decryption: { read LDEA-key,R-key,n,C for i=1 to n { Rrotate(C) X=permute(C) Interlace(X) p= X LDEA key P=convert(p) } Permute(P) write P; } 4 Application to Images : An image is a set of finite number of elements of the form (x,y,f(x,y)), where x and y are two dimension coordinates and f(x,y) is the intensity or grey level of the image at that point. In image processing, point distribution models are used to represent the shapes of the objects. In an image if the image intensity f(x,y) is uniform at every (x,y) then we can ignore f(x,y) and assume the image to be a set of points of the form f(x,y). The point distribution models deals with this sort of images . A cryptographic representation of a plane bounded externally by an ellipse and internally by a circle is taken. A set of points are considered for the outer boundary and another set for the inner boundary. The image is transformed from one form to another using the encryption algorithm. It is observed that the latter does not exhibit any resemblance with the former.
Figure 1(a) Encryption
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Prasad Reddy P.V.G.D et. al. / International Journal of Engineering Science and Technology Vol. 2(5), 2010, 1060-1065
Figure 1(b) Encryption
Figure 1(c) Encryption
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Prasad Reddy P.V.G.D et. al. / International Journal of Engineering Science and Technology Vol. 2(5), 2010, 1060-1065
Figure 2 (a) Decryption
Figure 2(b) Decryption
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Prasad Reddy P.V.G.D et. al. / International Journal of Engineering Science and Technology Vol. 2(5), 2010, 1060-1065 5.Conclusions: In present paper a cipher is developed by interlacing and using the LDEA key dependent permutation and rotation as the primary concept. The technique is applied to images It is observed that the image is totally distorted 6. Acknowledgements: This work was supported by grants from the All India Council for Technical Education (AICTE) project under RPS Scheme under file No. F.No.8023/BOR/RID/RPS-114/2008-09. 7. References: [1] [2] [3] [4] [5] [6]
[7] [8] [9] [10] [11] [12] [13] [14] [15]
K.R.Sudha, A.Chandra Sekhar and Prasad Reddy.P.V.G.D “Cryptography protection of digital signals using some Recurrence relations” IJCSNS International Journal of Computer Science and Network Security, VOL.7 No.5, May 2007 pp 203-207 A.P. Stakhov, ”The ‘‘golden’’ matrices and a new kind of cryptography”, Chaos, Soltions and Fractals 32 ( (2007) pp1138–1146 A.P. Stakhov. “The golden section and modern harmony mathematics. Applications of Fibonacci numbers,” 7,Kluwer Academic Publishers; (1998). pp393–99. A.P. Stakhov. “The golden section in the measurement theory”. Compute Math Appl; 17(1989):pp613–638. Whitfield Diffie And Martin E. Hellman, New Directions in Cryptography” IEEE Transactions on Information Theory, Vol. -22, No. 6, November 1976 ,pp 644-654 Whitfield Diffie and Martin E. Hellman “Privacy and Authentication: An Introduction to Cryptography” PROCEEDINGS OF THE IEEE, VOL. 67, NO. 3, MARCH 1979,pp397-427 Tzong-Mou Wu “One-to-one mapping matrix” Applied Mathematics and Computation 169 (2005) 963–970 A. V. N. Krishna, S. N. N. Pandit, A. Vinaya Babu “A generalized scheme for data encryption technique using a randomized matrix key” Journal of Discrete Mathematical Sciences & Cryptography Vol. 10 (2007), No. 1, pp. 73–81 C. E. SHANNON Communication Theory of Secrecy Systems The material in this paper appeared in a confidential report “A Mathematical Theory of Cryptography” dated Sept.1, 1946, which has now been declassified. E. Shannon, A Mathematical Theory of Communication, Bell System Technical Journal 27 (1948) 379–423, 623–656. A. Chandra Sekhar , ,K.R.Sudha and Prasad Reddy.P.V.G.D “Data Encryption Technique Using Random Number Generator” Granular Computing, 2007. GRC 2007. IEEE International Conference, on 2-4 Nov. 2007 Page(s):573 – 576 V. Tolety, Load Reduction in Ad Hoc Networks using Mobile Servers. Master’s thesis, Colorado School of Mines, 1999. L. Scott, D. Denning, Geo-encryption: Using GPS to Enhance Data Security, GPS World, April 1 2003. Geo-encryption protocol for mobile networks A. Al-Fuqaha, O. Al-Ibrahim / Computer Communications 30 (2007) 2510–25 PrasadReddy.P.V.G.D, K.R.Sudha and S.Krishna Rao “Data Encryption technique using Location based key dependent Permutation and circular rotation” (IJCNS) International Journal of Computer and Network Security,Vol. 2, No. 3, March 2010 pp46-49 Prasad Reddy.P.V.G.D, K.R.Sudha and S.Krishna Rao Rao “Data Encryption technique using Location based key dependent circular rotation” Journal of Advanced Research in Computer Engineering, Vol. 4, No. 1, January-June 2010, pp. 27 – 30
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