Data Security and Transmission over WirelessNetworks

Saurabh NambiarSuryaPrabha C P

Smruthi KShijil

1Department of Computer Science andEngineering

Govt. College of Engineering, Kannur

Under the Guidance ofMr. Nidheesh N.

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Project Outline

• About the Project

• Introduction

• Motivation• About the Work

◦ Encryption Phase◦ Encoding Phase◦ Pixel Modification and Splitting◦ Overlapping Phase◦ Decoding Phase◦ Decryption Phase

• Testing and Results

• Conclusion

• Future Work

• References2 of 1

About the Project

The Project aims at secure data hiding of confidential informationand its transmission over networks. The proposed system provides thebest approach for Least Significant Bit (LSB) based steganographyusing Genetic Algorithm (GA) along with Visual Cryptography (VC).Original message is converted into cipher text by using secret key andthen hidden into the LSB of original image. Genetic Algorithm andVisual Cryptography has been used for enhancing the security.Genetic Algorithm is used to modify the pixel location of stego imageand the detection of this message is complex. Visual Cryptography isused to encrypt the visual information. It is achieved by breaking theimage into two shares so that the hidden data is also split. The mainaim of this paper is to design the enhanced secure algorithm whichuses both LSB steganography using Genetic Algorithm and VisualCryptography to ensure improved security and reliability.

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Introduction

The main aim of the project is to design a feasible RS steganalysisresistant secure Algorithm which combines the use of bothsteganography and cryptography with the goals of improving security,reliability, and efficiency for secret message. DES encryptionalgorithm is used for encrypting the data into cipher text. Apart fromthat, LSB Steganography is combined with the Visual Cryptographymaking it more secure from RS steganalysis.

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Introduction

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Introduction

The Project is divided into following important six phases:

• Encryption Phase: The data to be encrypted is first inputted bythe user.The encrypted text is called cipher text. The encryptionalgorithm used is DES, which is comparatively considered moresecure than RSA encryption.

• Encoding Phase : The encrypted cipher is then encoded into theleast significant bits of an appropriate image.

• Pixel Modification & Splitting Phase : Since the LSBsteganography can easily be detected by RS steganalysis, theinformation pixels at the LSB have to be distributed throughoutthe image randomly. After this random distribution, the image isdivided into two shares(parts) before its transmission. This ensuresthat information pixels are distributed into two shares.

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Introduction

• Overlapping Phase: To retrieve the information, both the shares ofimage are required. Both the shares are combined into a singleimage in this phase. The image generated consists of theinformation.

• Decoding Phase: The data in the encrypted form is retrieved backfrom the stego-image.

• Decryption Phase:The original data is retrieved back using theDES decryption algorithm using the same secret key.

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Motivation

• The primary reason for selecting steganography among the list ofpossible project topics was due to the unfamiliarity of the wordthat twigged an interest in the subject.

• Another reason is the data security that it provides. Even if thehacker(or intruder) gets access to our multimedia data, then alsohe cant access the information, that is, the hacker has done thedifficult part of hacking and getting access to the data but theactual data is still under his nose. This aspect makes it moreinteresting.

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Related Work

• There exists many information hiding softwares in the market butmost of them are based on LSB Steganography.

• LSB Steganography can easily be detected by RS steganalysis.Hence, security level is low.

• There are many papers related to the combination ofsteganography with cryptography. These provide an additionallayer of protection over the cryptographic model.

• A combination of Cryptography and Steganography is moreresistant to RS Steganalysis.

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About the WorkEncryption Module

• The original data to be encrypted is given as input by the user.

• The encryption algorithm used is DES (Data Encryption Standard).

• DES is a private key encryption scheme, that is, only the senderand receiver know the secret key.

• DES uses a 56-bit secret key to encrypt data.

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About the WorkDES Algorithm

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About the WorkDES Algorithm

• DES is based on a cipher known as The Feistily block cipher.

• To accomplish encryption, most secret key algorithms use twomain techniques known as substitution and permutation.

• Substitution is simply a mapping of one value to another whereaspermutation is a reordering of the bit positions for each of theinputs.

• The two inputs for DES algorithm are: plain text to be encryptedand the secret key.

• DES is therefore a symmetric, 64 bit block cipher as it uses thesame key for both encryption and decryption and only operates on64 bit blocks of data at a time (be they plaintext or ciphertext).

• The key size used is 56 bits, however a 64 bit (or eight-byte) key isactually input.

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About the WorkDES Algorithm

• Once a plain-text message is received to be encrypted, it isarranged into 64 bit blocks required for input. If the number ofbits in the message is not evenly divisible by 64, then the last blockwill be padded.

• Multiple permutations and substitutions are incorporatedthroughout in order to increase the difficulty of performing acryptanalysis on the cipher.

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About the WorkEncoding Phase

• In the encoding phase, the cipher data obtained is written into anappropriate image.

• The image and the cipher data is first converted into a byte arrayrepresentation.

• To encode the data into an image, some bitwise operations arerequired.

• Some of the bitwise operations are as follows:◦ AND operator:

01010111 = 8701100101 = 10187 & 101 = 01000101 = 69

◦ OR operator:01010111 = 8701100101 = 10187 OR 101 = 01110111 = 119

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About the WorkEncoding Phase

• When left shifting the bits, if the first bit is not a 1, then a singleleft shift will double the value.01010111(87) shiftleft 1 = 10101110(174)

• Right Shift is just the opposite of left shift.01010111(87) shiftright 1 = 00101011(43)

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Encoding Module

Some of the important steps involved in Encoding Phase:

• First for loop loops through each byte in the addition array and second for loop loops though each bit in a bytestored in add

• Next, variable b is assigned the value of either 0 or 1

• 0xFE is hex, which represents 11111110 in binary. By reasoning above, this will leave the first 7 bits as is, and clearthe least significant bit to 0. Then with the last bit 0, we OR it with b, which is either: 00000000 or 00000001.This will set the last bit to match the value stored in b.

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Pixel Modification Phase

• The data in the LSB of an image is not a secure way to hide thedata. The process of steganalysis can easily detect such images forthe presence of hidden data.

• Inorder to make the stego-image RS resistant, the pixels in theimage are modified so that the hidden data is distributedthoughout the image.

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Splitting and Overlapping Phase

• In the splitting phase, the image is divided into two shares.

• Each share of the image contains a set of pixels of the originalimage. The idea behind this is that the information(hidden text)isnow divided into these two shares.

• First, the source image is divided into black and white, that is, theimage contains only black and white pixels.

• Secondly, a key image is generated of the same dimensions, whereeach pixel is randomly set to white or black.

• Third, the original image is encrypted using this key - if the pixel inthe key is white then the corresponding pixel in the original imageis used in the encrypted image, whereas if the key pixel is blackthen the corresponding pixel in the original image is flipped (blackto white, white to black) for the encrypted image. The result istwo images of apparently random black and white pixels.

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Splitting and overlapping Phase

• Finally, each image is then doubled in size - each pixel becomes a2x2 square of pixels. Black pixels have black pixels in the top-leftand bottom-right corners while the other two pixels are white,while a white pixel in the original image produces the opposite 2x2square.

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Splitting and Overlapping Phase

• Overlapping phase is done at the receiver side. The two shares of images that comprises of opposite pixels to eachother would produce the original image when overlapped.

• When the two shares of image are combined, we are actually combining the hidden text in the two shares.

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Decoding Module

Some of the important steps involved in Decoding Phase:

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Decoding Module

• The length of the message is stored as a 4 byte number, or 32 bits,thus the message starts after 32 bits of image.

• Since the first 32 bytes contain 1 bit each of our length, we mustloop all 32 bytes to retrieve the length.

• Shift the bits of length left by 1, then OR it with a result of theleast significant bit of the image byte. (& 1) will clear all bits,except the last bit, which will be left as is. Thus as bits are added,they are moved along and placed into the newly empty leastsignificant slot of length.

• Create a byte array to hold the bits.• Loop through the image bytes till entire bits are retrieved.• Second for loop is to loop through the 8 bits of a byte.• The resulting array of bytes is made up of the least significant bit

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Decryption Phase

• The cipher text obtained in the previous phase is converted back tothe original data.

• The DES encryption scheme is used for decrypting the data.

• DES algorithm uses a symmetric key, that is, the secret key usedto decrypt the data is same as that used for encryption.

• Since, DES encryption is private key encryption, only the senderand receiver of data know about the secret key.

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ResultsSnapshots

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Snapshots

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Snapshots

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Snapshots

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Snapshots

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Snapshots

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Snapshots

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Snapshots

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Future Work

• Transmission of data in highly secured manner through audiostreams and video streams.

• Send the any multimedia data in encryted form with audio, videoor text format.

• Enhanced to support digital watermarking.

• Many research work is going on in this direction to preventsteganographic images from steganalysis.

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Conclusion

• This software has securely implemented least significant bitmanipulation based steganography that uses the DES algorithmand genetic algorithm along with visual cryptographic technique.

• It can be concluded that when normal image security usingsteganographic and visual cryptographic technique is applied, thedecryption of the encoded authenticated data becomes acumbersome effort. The security features of the steganographictechnique are highly optimized using the least significant bitmanipulation along with visual cryptography.

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References

• ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6508373

• www.techrepublic.com/resource-library/whitepapers/integratingsteganography-using-genetic-algorithm-and-visual-cryptography-for-robustencryption-in-computer-forensics/

• asprs.org/a/publications/pers/2009journal/may/2009may557-567.pdf

• www.ijcsit.com/docs/Volume%203/vol3Issue3/ijcsit20120303112.pdf

• en.wikipedia.org/wiki/Data Encryption Standard

• docs.oracle.com/javase

• www.doc.ic.ac.uk/ nd/surprise 96/journal/vol4/tcw2/report.html

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Thank You ! ! !

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