CALEB WALTER 7/14/2013 Audio Stego – A Brief How To

What is Audio Steganography? Hiding Data inside Audio files (WAV, MP3, WMA, etc) Digital Audio differs from Analog Audio  Continuous Signal vs Discrete Signal  Sampled at a continuous rate (CD: 44Khz) Data is hidden by slightly changing the discrete signal to remain inaudible

Encoding Data in Audio Multiple Tools to encode audio into MP3 file and format  MP3Stego – Takes a.TXT file and.WAV File and Encodes and formats into a MP3 File  Coagula – Encodes an Image into an MP3 or.WAV File

Encoding with MP3Stego Create a sample.TXT file with your desired encoded message Save this Desired Message into the Same Folder as your.WAV

MP3Stego Encoding Cont. Find Desired.WAV File (I chose Classic Mr.T)  Make Sure it is in the same Directory as the Earlier.TXT File Load up MP3Stego GUI  Select “Encode TXT file in an MP3 File”

Encoding with MP3Stego Cont. Select your Desired Encoded Message in “Select Original TXT File” box Select your chosen WAV file to encode in “Select Original Sound File” box Type the desired name of your newly encoded MP3 in the “Output File” box

MP3Stego Encoding Cont. Press “Encode File!!!” Button to begin Encoding To enter a password to protect against random decoding, type desired Password into box  You will not see the text you type, so make sure you get it right!

Encoding with MP3Stego After Pressing Enter and confirming any desired passphrase, an Encoded MP3 File will be saved into the same directory as the.WAV and.TXT

Encoding with Coagula Create an Image with your preferred Image Creation/Modulation Software  I chose Paint  A Small Image without much empty space will work best

Encoding with Coagula Open up Coagula and go to File: Open Image Find your created image in the directory and press Open

Encoding with Coagula Either go to the Sound Drop down Menu and press “Render without Blue” or Press the button with Green and Red gears to render the image as sound Newly Encoded.WAV file will be saved as Coagula.wav in Coagula Directory

Decoding with MP3Stego Open Up MP3Stego and Select “Decode TXT File from an MP3 File” Select your Encoded MP3 File from before and in “Select MP3 to Decode:” box

Decoding with MP3Stego Enter in any established passphrase for your file within the Passphrase box Press Enter and a.TXT file bearing the name of the encoded MP3 file will appear in the directory

Decoding with Sonic Visualizer Open Up Sonic Visualizer and open the encoded.WAV File into the Visualizer  You will only see Audio Spectrum for now Go to Menu and press “Add Spectogram”  For this application any and all submenu options will have no effect

Future Methods for Audio Steganography Echo Hidden – Echo Inside Audio File, hiding data within the echo so that it is undeterminable to the human ear Song Filtering – Running multiple FIR filters over a song to encode data into it, without changing the sound or file size

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