Audio video steganography using forensic techniquefor data security

1. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
154
AUDIO - VIDEO STEGANOGRAPHY USING FORENSIC
TECHNIQUEFOR DATA SECURITY
Athira Mohanan, Reshma Remanan, Dr. Sasidhar Babu Suvanam, Dr. Kalyankar N V
Department of Computer Science & Engineering,
Sree Narayana Gurukulam College of Engineering, Ernakulam, India
ABSTRACT
Steganography means, a method for hiding secret information for example password text or image inside a
cover file. In this paper, a combination of audio steganography and image steganography is used and also forensic
technique is used for authentication. The aim is to hide secret data in the audio and image of a video file. Video has so
many still frames of image and audio, we can select any frame for hiding our data. Two algorithms can be used for this
purpose.4LSB for image steganography and phase coding algorithm for audio steganography.
Keywords: 4LSB; Data Hiding; Steganography; Computer Forensics; Histogram; PSNR; Authentication.
I. INTRODUCTION
Steganography means covered writing. Goal is to hide the fact that communication is taking place. This is
achieved by using a cover file and embedding the secret message into this file. The result is stego file containing the
secret message. Stego algorithm downloads are now available on internet. Governments, military, businesses and private
citizens now use steganography for security and privacy purpose. Combination of image and video steganography is
used. Computer forensic technique is used to find the parameter like frame number, height and width of data, PSNR,
histogram of secrete message data before and after hiding to audio-video. If all these parameters are verified and found to
be correct then it will send to receiver otherwise it stop the message in computer forensics block.
II. RELATED WORKS
In previous, cryptography is used for encryption of data and provides data security. But actually term
cryptography provides privacy. Privacy is what you need when you use your credit card on the Internet — you don’t
want your number revealed to the public. For this, you use cryptography, and send a coded pile of gibberish that only the
web site can decipher. Though your code may be unbreakable, any hacker can look and see you’ve sent a message.
[2][3][4]
To overcome this drawback steganography is used for sending data like image and audio and make hidden.
Steganography is intended to provide secrecy. [1] Steganography approach that makes use of Least Significant Bit (LSB)
algorithm for embedding the data into the bit map image (.bmp). This approach is to replace the data of lower bit in a
cover audio data by a secret data. Our system is designed by using 32-bit ARM controllers for designing predictive
model for image and audio steganography system. The proposed method will help to secure the content with in the image
and encryption of audio file with in the image will help to make the document much securer because even though if the
unauthorized person succeeds in being able to hack the image, the person will not able to read the message as well as
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2. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
155
acquire the information in the audio file. Secret data like image and audio is encrypted into cover data by developing the
application involved with LSB algorithm on ARM architecture device.
III. SELECTING AUDIO-VIDEO FILE
• Select any available .avi audio-video file, behind which user want to hide data.
• Separate audio and video from selected audio-video file using available s/w ‘Easy Audio-Video Separator’.
• Save audio file as .wav file, this is the original separated audio file.
IV. VIDEO STEGANOGRAPHY
• Select original video file. Read file using ‘VideoReader function’.
• Collect all frame’s structure in one variable using ‘mov’ function.
• Read the structure. Play video using ‘movie’ function.
• Accept one of the frame no from user, behind which an authentication image is to be hidden.
• Read the frame and store it in variable ‘a’.
• Select one of authentication image read that image and store it in variable ‘b’.
• To extract msb of frame, bitand frame with 240 using function ‘bitand’.
• To extract msb of authentication image, bitand image with 240 using function ‘bitand.
• Reverse the place of msb of authentication image to lsb by dividing each element by 16.
• Reshape the image bits into one row.
• This reshaped row vector of authentication image data is embedded on the frame matrix, by adding each row
vector bits to last 4 bits of frame bits.
• This forms a stego frame, overwriting this stego frame with original video file create stego-video file.
• Using ‘VideoWriter’ function new create stego-video file, in which authentication image is hidden.
• Close the file.
V. CREATING STEGO AUDIO FILE
• Combine stego audio and stego video file using ‘Cute audio video merger’.
• This forms the stego audio-video file at transmitter side which has hidden text and image in it.
VI. AUTHENTICATION (AT RECEIVER SIDE)
• After transmission the stego audio-video file obtained at receiver side.
• Read the stego audio-video file; store the data in one variable ‘a1’.
• Select the frame no. The frame no should be same at transmitter and receiver side, then only the authentication
process start else it gets terminated.
• To recover the authentication image from the selected frame bitand frame data with 15 using ‘bitand’ function.
• Authentication image data is available at Lsb of frame recovered. It is in row vector.
• Reshape the row vector data into matrix using ‘reshape’ function.
• Select the authentication image at receiver side. Compare recovered authenticated image with the selected
image.
• If both the images matched, then only user can recover the text behind audio else process is terminated.
VII. AUDIO RECOVERY
• Audio file is read using function ‘wavread’, sample data is store in ‘y’.
• Open this stego audio file in read mode using function ‘fopen’.
• Read wave file’s first 40 bytes of header using ‘fread’ function and store it in a variable ‘header’.
• Then read all its data after 40th
byte using same function and store it in ‘dta1’ variable.
• Close file using ‘fclose’ function.
• Recover the size of identity key from lsb of .wav file. Recover identity key from further lsb bits of .wav file.
• Accept identity key from user and compare entered identity key with recover identity key. If both the keys
matched then only user can recover the hidden text else processes will be aborted.
• As identity key is matched recover the size of message from further lsb bits of .wav file. Recover the message.
• Secrete text is recovered.

3. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
156
VIII. COMPUTER FORENSICS AND AUTHENTICATION
• Phase coding exploits the human audio system insensitivity to relative phase of different spectral components.
• The basic idea is to split the original audio file into blocks.
• Then embed the whole message data sequence into the phase spectrum of the first block.
• One drawback is low payload because only first block is used for secret message embedding.
• The secret message is not distributed over the entire file so it can be easily removed using cropping attack.
• The phase coding algorithm is explained in the following procedure:
• The original sound signal is segmented to extract the header.
• The rest portion is broken up into smaller segments.
• The size of this will be equal to the message to be encoded.
• A discrete Fourier transform is applied to each segment to create a matrix of phases.
• The secret message is inserted in the phase vector of the first signal segment as follows:
Oldphase+pi/2, for bit ‘0’.
New phase=old phase-pi/2, for bit ‘1’.
• A new phase matrix is created using new phase of first segment and original phase matrix.
• Using new phase matrix sound signal is reconstructed by applying inverse DFT.
• Then concatenating the sound segments with original header.
IX. ALGORITHM FOR HIDING DATA IN AUDIO
• Start and accept audio name along with full path from user to extract the audio using s/w ‘Easy video to audio
converter’. Extract the audio file in ‘.wav’ format and save this audio file in a specific folder.
• Accept this audio file in MATLAB using the function ‘uigetfile’.
• Read the file using ‘wavread’ function. Thisfunction returns the sampled audio data, no of bits per second and
sampling frequency.
• Open this file in ‘read’ mode using ‘fopen’ function,this function returns a file ID.
• First 40 bytes of a file make wav header,store the header in variable ‘header’.41st
byte to 43rd
byte represents
the length of wav data samples.Hence,copy the 16 bit
wav data samples starting from 44th
byte.
• Close the file only wav data samples are sufficient to hide the text.
X. TAKE THE TEXT MESSAGE
• Convert the message into binary and reshape the message in column vector using the function ‘reshape’.
• Convert the audio data into smaller segments whose lengths equal the size of the message to be encoded.
• Apply DFT to each segment to create a matrix of the phases.
• Old phase+ pi/2, for bit ‘0’.
• New phase = old phase- pi/2, for bit ‘1’.
• Create new phase using new phase of first segment and original phase matrix.
• Apply inverse DFT to reconstruct sound signal.
• Open a new audio file to ‘write’ mode.
• Copy the header of original wave file to a new file.
• Close the file.
• End.
XI. ALGORITHM FOR RECOVERING THE HIDDEN TEXT
• Start.
• Accept the stego-audio file in MATLAB using the function ‘uigetfile’.
• Read the file using ‘warhead’ function. This function returns the sampled audio data, no of bits per second and
sampling frequency.
• Open the file in ‘read’ mode using ‘fopen’ function, this function returns a file ID.
• Close the file, only wav data samples are sufficient or extracting the text.
• Extract the binary length, phase, extract binary text and convert it into decimal and characters respectively.
• End.

4. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
157
XII. ALGORITHM FOR TRANSMITTER SIDE
• Select the cover video and split into frames.
• Enter the pass-key and the cover frame from cover video will be selected as per the pass-key.
• Enter the secret message andconvert it into binary form.
• Hide secret message inside cover frame using 4LSB algorithm to get stego frame.
• Hide authenticationkey using same algorithm inside fixed frame.
• Replace original frames chosen for hiding secret message and authentication info by those stego frames.
• Recombine frames to form stego video and transfer it using any communication.
XIII. RECEIVER SIDE
Get the stego video and split it into frames.
• Take authentication key from user and cross check it with that in the stego video at specified frame.
Ifauthentication fails go to step 7 otherwise continue.
• Enter the pass-key when asked and pass-key selects stego frame along with adjacent frames.
• Using forensic check presence of any hidden data. If forensic check fails go to step 7 otherwise continue.
• Extract data from stego frame by the use of reverse 4LSB algorithm and store it in a file.
XIV. CONCLUSION
To provide high end security to the data to prevent form the attackers, a dynamic method can be used. Two
things are important to provide security to the data confidentiality and encryption. Use sign cryption technique to provide
high security to the data, by encrypting the data with digital signature. Because of this the attacker cannot do any kind of
modification to the data. Then embed the data in an audio video file using audio-video Steganography to confuse the
attacker. In this way we can provide highly strong security.
ACKNOWLEDGMENT
This research was supported by Sree Narayana Gurukulam College of Engineering, computer science and
Engineering, Kerala.
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