A SECURE IMAGE STEGANOGRAPHY FOR SPEECH ...DESCRIPTION OF AES ALGORITHM STEP 1: Key Expansion Round keys are generated from cipher keys using the algorithm (AES) key schedule. AES

A SECURE IMAGESTEGANOGRAPHY FOR SPEECHDATA HIDING IN DIGITAL IMAGES

NIHARIKA RAMACHARLA1, SINDHU PRIYA2

and DR.E.LOGASHANMUGAM3

1 2student,Department of Electronics and Communication Engineering,

Sathyabama University, Jeppiaar Nagar,Rajiv Gandhi Salai, Chennai, India.

[email protected],[email protected]

[email protected]

January 4, 2018

Abstract

Hiding messages in such a way that no one, apart fromthe sender and receiver, suspects the existence of the mes-sage is called Steganography. The new algorithm is basedon hiding a large amount of data (image, audio, text) fileinto color BMP image. The adaptive image filtering andadaptive image segmentation with bits replacement on theappropriate pixels is used. These pixels are selected ran-domly rather than sequentially by using new concept de-fined by main cases and sub cases for each and every bytein one pixel. This concept is based on both visual and sta-tistical. According to the steps of design, the conclusion of16 main cases with their sub cases covers all aspects of theinput data into color bitmap image. High security layers areproposed through three layers to make it difficult to breakthrough the encryption process of the data and to confuse

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International Journal of Pure and Applied MathematicsVolume 118 No. 17 2018, 509-522ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu

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steganalysis too.

Key Words : Steganography, Adaptive image filtering,Main cases and sub cases, Encryption, Stego image.

1 INTRODUCTION

In todays internet world the data communication need to be fast aswell as secured. There are many ways to make the communicationfast, but at the same time securing the data while transmission isvery important. So data hiding has become the most essential thingfor Network Security. Flexible software with low prices of digitaldevices like music players and other portable devices have madeit feasible for consumers from all over the world to create and ex-change multimedia data. Consumers exchange sensitive messagesand files over internet and everyone might have some informationto be kept in secret. Steganography is a powerful tool which in-creases security in data transferring. In steganography, the data tobe hidden is first concealed within a file which is called cover andforms another new object called stego and then this new file can betransmitted or saved. The different formats that can be used forsteganography are Text, Images, Audio, Protocol. Image steganog-raphy is one of the important and famous data hiding techniquesthat embeds secret data into an image signals using encryption anddecryption.

The following steps are to be followed for encrypting and de-crypting the hidden message.

Figure 1: Encryption and Decryption process

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Encryption: The content of the message is encoded in such away that hides its contents from other unauthorized persons. Plain-text is converted to cipher text by applying the encryption processwith the help of an encryption key.

Decryption: It is a process of retrieving the plaintext backfrom the cipher text.

Key: Both Encryption and decryption make use of a key. Onthe sender side, all data-hiding applications require hiding algo-rithms and require a detector mechanism or algorithm on the re-ceiver.

2 EXISTING WORK

A new algorithm called Symmetric Key Algorithm using extendedMSA method is used which describes about a symmetric key methodwhere a random key generator generates the initial key. The ini-tial key generated is used as secret key for encrypting the givensignal. For searching the characters, MSA algorithm by Nath wasused. The algorithm itself calculates the randomization number aswell as encryption number needed to encrypt the message. For thedecryption part, user must surely know the secret key matrix com-bination defined in the encryption part. This algorithm consists ofall the possible word combinations, each generated by the ASCIIcode from 0 to 255 in a random manner. The author had appliedthis algorithm on MS word file, MS Excel file, MS access, text file,image file, audio file, PDF file, video file and found the correctsolution for encryption when the file size is 2 MB. Its a challengefor hiding encrypted message in LSB and LSB + 1 bit positions invarious cover files, here the secret message is encrypted by MSAalgorithm by Nath and further the encrypted message hided insidethe cover file by changing the LSB and LSB + 1 bits of cover file.These methods are very useful for embedding data in non standardcover files. In this paper the size of the secret key must be lessthan or equal to 16 characters from any of 256 ASCII characters.To find the encryption key for a particular secret data, randomiza-tion number, encryption number and relative shift is calculated andaccording to that process position of the character gets changed.The size of the secret file and secret key is hidden inside the LSB

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bits of cover file .Here speech scrambling techniques are used toscramble the secret speech data. In this method the speech signalsare encrypted by using different pseudo-noise sequences, comparedby informal listening tests and signal inspection method in timeand frequency domains. Pseudo-noise sequences have random likeproperties which are used in reducing the correlation between thespeech samples. The speech encryption is done using pseudo-noisesequences which makes the speech signal un-understood since it re-moves the correlation between the samples of speech signal whichneed to be transmitted. For hiding Encrypted data in image file,data encryption standard asymmetric algorithm is used to designencipher and decipher blocks of data consisting of 64 bits under thecontrol of 64 bits key. Cryptography technique is applied on audioto increase the security of audio data during transmission. Theencrypted message consists of background noise, hiss and clickingnoise which represents meaningless to the unauthorized person. Inthis method though one level of encryption is being broken the restof levels prevents the actual audio data file from losing its integrity.

Figure 2: SNR analysis of existing system

3 PROPOSED METHOD

In the proposed method we introduce the three level Security andthe methodology in each level is as follows:

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1. Adaptive segmentation done by the input password we giveas a user.

2. Pixel Selection which is done using the concept of main casesand sub cases.

3. Security using the advanced encryption algorithm.

ADAPTIVE SEGMENTATION OF THECOVER-IMAGE

The image taken as the cover image is the JPG image. The coverimage is segmented randomly of irregular segments based on thepassword given. Non uniform segmentation gives more security forgiving the input. Lossless compression technique is applied for theJPG image for sending large files. To reconstruct the original imageexactly this lossless compression technique is used. The algorithmfor that is shown in figure 4.

Figure 3: Image Segmentation

Figure 4: Flow chart of Adaptive Segmentation

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PIXEL SELECTION STYLE

One Performs random selection to exact byte at each pixel ofthe cover-image according to its color characteristics. This is toembed the secret data. This type of selection is done by using theconcepts which are called main cases and sub cases.

Main case:JPG image consists of 24bits, each byte is divided into two nib-

bles (4 bits). The nibble value is fixed by the interval [0, 15], sothat there are 16 weighted bits, each one represents one main case(MC) out of 16.

MC=round (Byte colou4Rr /16)+1

where Byte ColorεRed, Green, Blue represents the value ofColor in decimal notation.

Sub case:Sub-case (SC) concept is used to organize the pixel architect.

There are 8 SCs. Every MC has a number of SCs.

Figure 5: Original audio signal

The Audio signals are encrypted by using different pseudo-noisesequences where these have random like properties and are used in

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reducing the correlation between all the speech samples. The speechencryption using pseudo-noise sequences make the speech signal ununderstood by removing the correlation between the samples of thespeech signal.

Figure 6: Encrypted audio signal with 15 dB noise

AES (advanced encryption standard) data encryption is a moremathematically efficient and elegant steganographic algorithm, butits main strength lies in the length of the key. The time required tocrack an encryption algorithm directly depends on the length of thekey used to secure the communication. AES stands for AdvancedEncryption Standard. It is a symmetric encryption algorithm de-veloped by Belgian cryptographer Joan Daemen and Vincent Rij-men. AES supports a block length of 128 bits and key lengths of128,192 and 256 bits. It has been adopted by US government andis now used worldwide. This advanced encryption standard wasdeveloped in 1998. AES is based on design principle called sub-stitution permutation network. The key size used for AES cipherspecifies repetition of rounds that converts the input plain text intofinal output cipher text.

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Figure 7: Architecture of Image Steganography

There are ten cycles of repetition for 128 bit keys, twelve cy-

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cles of repetitions for 192 bit keys and there are fourteen cycles ofrepetition for 256 bit keys.

Figure 8: Embedded Input

Figure 9: Audio Output

DESCRIPTION OF AES ALGORITHM

STEP 1: Key ExpansionRound keys are generated from cipher keys using the algorithm

(AES) key schedule. AES requires a separate 128 bit round keyblock for each round plus one more.

STEP 2: Initial Round

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Add round keyhere, using bitwise XORs, each byte of the stateis combined with a block of round key

STEP 3: Roundsi) Sub Bytes- it is a non linear substitution stepwhere each byte is replaced with another are according to look

up tables.ii) Shift Rows- It is a transposition step where last three rows

of state are shifted cyclically a certain number of steps.iii) Mix Columns- here mixing operation is performed which op-

erates on columns of state, combining four bytes in each column.

STEP 4: Add Round KeyHere sub bytes, shift rows and add round key operations are

performed (mix columns is not performed)

4 RESULTS

Figure 10: SNR analysis of proposed system

Signal to noise ratio (SNR) is improved to 97.7 from 56.73.Security has been increased by using adaptive segmentation and

pixel selection.

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5 CONCLUSION

The original image and stego image with encrypted secret speechfile is shown in Fig 8. In this paper a method to secure the speechsignal message hidden inside the cover image is developed withadditional layer security. The secret key is generated within theAdvanced Encryption Standard algorithm where the decryption ofhidden file one has to go through 2512 combinations of charactersand numbers which is very difficult for attackers to hack the secretdata.

The secret data will be received by the authorized person atreceiver end only when the secret key also called as password isentered correctly. The proposed method is very secure and alsoimproves the signal to noise ratio of audio signal.

References

[1] Altaay,J.S.Sahib and Mazdak Zamani, An Introduction to Im-age Steganography Techniques,in International Conference onAdvanced Computer Science Applications and Technologies,2012, pp.122-126.

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[3] Divya Sharma, Five level cryptography in speech processing us-ing multi hash and repositioning of speech elements, Interna-tional Journal of Engineering Technology and Advanced Engi-neering, Vol. 2, No. 5, PP. 21-26, 2012.

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[10] Kruus.P, C. Scace,M. Heyman, and M. Mundy(2003), A surveyof steganography techniques for image files. Advanced SecurityResearch Journal.

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[14] Morkel.T An overview of image steganography by J.H.P. Eloff,M.S.Olivier.Information and Computer Security Architecture(ICSA) Research Group,Department of Computer Science Uni-versity of Pretoria, 0002, Pretoria, South Africa.

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[15] Nutzinger.M, Real Time attacks on Audio Steganography,Journal of Information Hiding and Multimedia Signal Process-ing, Vol. 3, No. 1, PP. 47-65, 2012.

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A SECURE IMAGE STEGANOGRAPHY FOR SPEECH ...DESCRIPTION OF AES ALGORITHM STEP 1: Key Expansion Round keys are generated from cipher keys using the algorithm (AES) key schedule. AES