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  1. 1. S.G. Gino Sophia, K.Padmaveni, Linda Joseph / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January -February 2013, pp.1492-1496 Four key Secured Data Transfer Using Steganography and Cryptography S.G. Gino Sophia, K.Padmaveni, Linda Joseph School of Computing Sciences and Engineering Hindustan UniversityAbstract Steganography and cryptography are other part of the program is protected on changingused to send the data in a confidential way. the decision of a design from the extensiveSteganography hides the existing message and modification. For better confidentiality security wecryptography will confuse the message. The use both cryptography and Steganography in thistransformation of plain text to cipher text is paper to develop one system. DES algorithm is acalled as encryption. The transformation of secured technique for cryptography andcipher text to plain text is called decryption. Steganography methods. Our idea is based onEncryption and decryption are controlled by combining these techniques the intruder may findkeys. Hashing, symmetric and asymmetric the original data, to get a highly secured system foralgorithms are cryptographic techniques. There data hiding. In data hiding the following areis a difficulty to find the hidden messages. For performed.this purpose various transformations like DCT, The part of a message which is encrypted will beFFT, FFT, and 2DDCT are used. A system is hidden instead of hiding message which is highlyproposed in this paper to develop a new encrypted.technique along with a newly enhanced security The encrypted message which are unhidden will bemodel in which cryptography and Steganography converted into two secrete keys.are used. In cryptography DES algorithm is used To get the original text along with keys forto encrypt a message and part of the message is Steganography and cryptography, two extra keyshidden in 2DDCT of an image and the rest of the and the reverse process of the key generation shouldmessage will generate two secrete keys for the be known. So the aim of the project is to developgeneration if high security. system which is more secured and even if the messages from stegno images are retrieved fromKeywords: Steganography, Cryptography, Data somebody [1], it becomes meaningless for anyhiding, 2DDCT, DES algorithm existing cryptographic techniques.I. INTRODUCTION II. BASIC CONCEPTS AND RELATED Information security is called cryptography WORK[3]. Some techniques included in cryptography are For security there are many aspects. One ofthe merging of words with images, microdots and the aspects for confidential communication is that ofthe different ways of hiding the data in storage. cryptography. The specific security requirements [8]Cryptography mainly concern with the conversion for cryptography are confidentiality, authenticationplain text into cipher text. This process is called and integrity, on-repudiation.encryption. The reverse of this process is called The following describes the four types ofdecryption. The four objectives in modern algorithms:cryptography are:(i)Confidentiality(unauthorized (a)Public key cryptography (PKC): uses oneperson will not be able to understand the public key for encryption and uses other private keydata)(ii)Integrity(The data can’t be altered in the for decryption.storage between sender and (b)Key distribution centre single key (KDC): Areceiver)(iii)Authentication(confirmation from the single key is shared with the key distribution centre.sender and receiver side) (iv)Non- repudiation(at the Key management and authentication is performedlater stage the sender will not be able to refuse the by KDC for communication key distribution isdata which is about for transmission). essential.Steganography, this hides information by (c)Shared secrete key: Both source and destinationembedding the messages within other. Replacement share the secrete key. It is also called as challengeof useless bits or used data is the work performed by response protocol.it. If the encryption is not allowed Steganography is (d)Hash function: To encrypt data irreversibly aused or otherwise encryption is supplemented by mathematical transformation is used. The otherSteganography. This encrypted file may also hide technique for communication is Steganography [7].information’s. The hidden messages will not be seen It transfers the messages by which it can’t beif the encrypted file is deciphered. Data hiding: The detected. The information can be hidden in audio, 1492 | P a g e
  2. 2. S.G. Gino Sophia, K.Padmaveni, Linda Joseph / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January -February 2013, pp.1492-1496video, text, images, or code [11] which is digitally reverse distortion process. Here the system isrepresentative. designed with three modules. (i)Crypto module for cryptographyA. DES algorithm for cryptography (ii)Stegno module for Steganography [10] and DES algorithm is a cipher block, which (iii)Security module for more securityencrypt data in 64 bit block. It is a symmetricalgorithm which uses same algorithm [13] and key A. Hiding the textfor encryption and decryption. This algorithm  Crypto module:encrypts and decrypts the blocks of data containing For the encryption of data the following steps are64 bits under 64 bit key controls. considered in crypto module [14]. Advantages of using DES algorithm  For encryption the text is inserted(i)The security of this algorithm resides in the key  DES algorithm is applied using 64bit key(ii)More secured as the length of the key is  Hexadecimal form cipher text is generatesincreased. Input DES Output hexaB. 2DDCT algorithm for Steganography string algorithm cipher text This 2 dimensional discrete cosinetransformations is a signal from spatial Figure1: Crypto modulerepresentation into frequency representation. Thanhigher frequencies, lower frequencies are more  Security Module:obvious on transforming an image [5] into To our newly developed system an extrafrequency components. By throwing away higher security feature is provided by this intermediatefrequency coefficients without sacrificing too much module. Cipher text is modified by this module toimage quality [15] , reduce the amount of needed generate two extra keys [6]. It regenerates thedata to describe the image.Over simplified Jpeg original cipher text on its reverse process. Thecompressor process of this module before hiding the process Image is cut into 8x8 pixel of chunks follows: Through an 8x8 2DDCT run each chunk  The alphabets and digits are separated from Resulting coefficients are quantified cipher text Quantified coefficients are compressed using a  The digits and the track of the original position losels’ methods of the alphabets are kept in the form of a secreteFormulae for 2DDCT: key (keyC)Ru=1/√2 if u=0  In first step, the first seven characters are 1 else separated, the remaining alphabets are added toRv = 1/√2 if v=0 the end of the separated digits as in the first step 1 else by which the second key (keyD) is guaranteed.elseFvu = Key 4 is generated by1/4 Rv Ru Syx cos(vπ adding remaining digits and2y+1/2N)cos(vπ 2x+1/2N) characterInverse Discrete Cosine Transform:Image can be rebuild in the spatial domain from Outputfrequencies HexadecimalIDCT formulae: First seven alphabets areRu=1/√2 if u=0 chosen for hidingelse Rv = 1/√2 if v=0 1 elseFyx=1/4 RvRu Fvucos(vπ2y+1/2N)cos(vπ 2x+1/2N) KeyCUntil the coefficient quantizing is started no image generatedis lost.DCT is perfectly reversible. from digits and original Digits and alphabetsIII. PROPOSED SYSTEM position of are separated from The two different techniques are combined the alphabet cipher textwhich is based on idea of distortion of message andhiding the existence of distorted message for gettingback the original information and retrieve the datawhich is distorted [2] and regain the actual text by Figure2: security module 1493 | P a g e
  3. 3. S.G. Gino Sophia, K.Padmaveni, Linda Joseph / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January -February 2013, pp.1492-1496 Stegno Module: Original sevenThe above guaranteed cipher text are hidden by the alphabets arefollowing steps: From the above discussed security module the retrieved seven alphabets are taken Using keyB 2DDCT of the unscramble The alphabets are scrambled using 128 bit key original image the disort 2DDCT of the image is found is taken seven By altering 2DDCT the cipher text is hidden alphabets Inverse 2DDCT is applied Stegno image is found 2DDCT of the Disorted From security Inverse stegno image is seven module seven 2DDCT taken alphabets are alphabets are constructed taken Difference of 2DDCT coefficient is From LSB of Alphabets Stegno image taken 2DDCT bits are are retrieved scrambled from the using 128 hidden seven bit key By altering 2DDCT, alphabets seven alphabets are Gray scale hidden Figure4: stegno module (reverse process) image is taken  Security Module(reversing process): 2DDCT of image is found For retrieving the cipher text the following steps are considered in the security module:Figure3: Stegno module The seven characters are clubbed with the alphabetsB. Retrieving text of keyD Stegno Module(reversing process):To retrieve the cipher text the following steps are The cipher text is reconstructed using keyC andconsidered in stegno module: keyD from digits and alphabets. 2DDCT of the original image is taken 2DDCT of the stegno image is taken Difference of 2DDCT coefficient is taken From reverse From LSB of 2DDCT bits are retrieved from stegno module the hidden seven alphabets the seven The distorted seven alphabets are constructed alphabets are Using keyB unscramble the distort seven retrieved alphabets Cipher text is Original seven alphabets are retrieved reconstructed in KeyC & D hexadecimal form Figure5: security module (reversing processing)  Crypto Module(Reversing Process): For retrieving the original text the following steps are Considered in crypto module: Retrieved cipher text is taken from the above Reverse DES algorithm by using keyA Original message is obtained. 1494 | P a g e
  4. 4. S.G. Gino Sophia, K.Padmaveni, Linda Joseph / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January -February 2013, pp.1492-1496 From keyB the rest of the alphabets are added back Cipher data Original data to seven characters which are retrieved from the image With the help of the keyA the digits and elements are reorganized to get back the original cipher data Reverse DES in the form of hexadecimal algorithm using keyA The original message from the cipher text is regenerated with the help of DES algorithm.Figure6: crypto module (reversing process) C. Advantage of the proposed system: The proposed system is highly secured becauseIV. IMPLEMENTATION DETAILSBy VC6.0 platform using VC++ this project is Let’s the combination of two secured techniquesdeveloped. The three modules taken part are a) DES for cryptographya) Crypt module b) 2DDCT for Steganographyb) Security module  NNumber of keys:c) Stegno module Four keys are used in this system a) For scrambling the cipher text one 56 bit privateA. Algorithm for the proposed system: keyIn DES algorithm we are getting the cipher text as b) For DES algorithm one 64 bit private keyhexadecimal form [9]. c) For retrieving the original data two extra private generated keyData is encrypted in units which are smaller than the The system is highly secured by using these twodefined block size. extra generated keys.Using cipher feedback mode, DES is converted into V. CONCLUSIONstream cipher. With the same key more than one The summary of this project is mentioned in themessage is encrypted and different initialization following points:vector is used.  AThe new system with the combination of cryptography and Steganography using 4 keys is Cipher feedback mode (CFB) is same as the block introduced.cipher. Here encryption is not parallelizable only  TThe method used for encryption using DESdecryption is parallelizable [12] and it has random algorithm is very secure and it is the main advantageaccess property. It is self recovery with respect to of this system. The 2DDCT transformationsynchronization errors. Steganography is very difficult to detect.A. Hiding text: REFERENCECipher text is generated in hexadecimal form by [1] Owen, M.,” A discussion of covertDES algorithm in the form of alphabets like . channels and Steganography”, SANSWith the help of a intermediate the alphabets and institute, 2002digits are separated and the original position of the [2]J. Zollner, H.federrath, H.klimant, etalphabets and digits are kept tracked in the form of al.,”modeling the security of systems:,first key(keyA). steganographic in 2nd workshop on information hiding,Portland,april 1998, The first seven characters of the alphabets are taken pp.345-355.July1999.and hidden in the image [3] D.R.Stinson, cryptography: Theory andThe rest of the alphabets are taken and combined practice, Boca Raton, Press, 1995.ISBN:with digits. This form the second key 0849385210 [4] M.M Amin, M.Salleh, S.Ibrahim,Then the seven characters are hidden in the image M.R.katmin, and M.Z.I. Shamsuddin,”mentioned in image 2.2 information Hiding using Steganography”, IEEE 0-7803-7773-March 7, 2003. B. Retrieving text [5] Marvel, L. M., Boncelet Jr., C.G.&Retter,From the image the seven characters are retrieved C.,”Spread spectrum Steganography”, IEEE Transactions on imageFrom keyB with the help of seperator2 the alphabets processing,8:08,1999and digits are separated 1495 | P a g e
  5. 5. S.G. Gino Sophia, K.Padmaveni, Linda Joseph / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January -February 2013, pp.1492-1496 [6] Alain C.Brainos II East Carolina university,” Study of Steganography and The Art of Hiding information”, November 13,2003. [7] Dunbar,B.,”Steganography techniques and their use in an Open-Systems environment”, SANS Institute,Januray 2002 [8]Stinsown,D.”Cryptography: Theory and Practice” [9] Neil F.Johnson, Zoran uric, Sushil jajodia,” Information hiding: steganography and watermarking attacks and countermeasures”, Kluwer academic press, Norway, MA, Newyork, 2000. [10] N.Provos, P.Honeyman,” Detecting Steganography content on the Internet”. Transformation”, ZEICE Tram. [11]Chandramouli, R., Kharrazi, M.& Memon,N.,’Image proceedings of the 2nd Workshop on Digital Watermarking, October 2003. [12] R A Isbell,”Steganography: Hidden Menace or Hidden saviour”, Steganography white Paper, IO May 2002 [13] Domenico Daniele Bloisi, Luca Iocchi: Image based steganography and cryptography, Computer Vision theory and applications volume1, pp.127-134 [14] E.T.Lin and E.J.Delp,”A Review of Data Hiding in Digital Images”, JUNE 20001 [15] Ros J.Anderson,Fabien A.P.petitcolas,” on The Limits of Steganography”, IEEE Journal of Selected Areas in Communications,16(4):474-481,May 1998. [16]http://www.xdp.itAbout Authors:S.G. Gino Sophia , M.Tech Computer Science andEngineering working as a Selection Grade Assistantprofessor, Hindustan university, Chennai has 9 yearsof teaching experience and has published 7international journal / conference papers.K.Padmaveni, ME Computer Science andEngineering working as a Selection Grade Assistantprofessor, Hindustan university, Chennai has 8 yearsof teaching experience and has published 9international journal / conference papers.Linda Joseph, ME Computer Science andEngineering working as a Senior Scale Assistantprofessor, Hindustan university, Chennai has 7 yearsof teaching experience and has published 8international journal / conference papers. 1496 | P a g e