mp3 stegonography lukasz grzegorz maciak micheal alexis ponniah renu sharma
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MP3 Stegonography
Lukasz Grzegorz MaciakMicheal Alexis Ponniah
Renu Sharma
Project Goal
Implement a method to embed textual data into audio files using stegonography
Embed lyrics into mp3 files Extract lyrics from an mp3 Display the lyrics while the song is
playing
Why MP3 Files?
Open Standard (as opposed to proprietary WMA)
Very Popular Preferred by end users Easily Available
FEATURES OF MP3
Designed to store audio data It’s a compressed file format It’s lossy data format meaning that
original audio signal is not retained in its entirety.
Aims to preserve the sound quality while minimizing storage space.
BASICS OF MP3 ENCODING
Takes into account the properties of HAS(Human auditory system)
Discards any sounds with frequencies out of the audible scale.
Mp3 stores only a single copy of group of similar sounding notes.
MP3 Encoding
Fragmentation: The size of the frame depends on the audio resolution or bit rate.
Perceptual Optimization: Each frame is analyzed so that frequencies that are not audible are discarded.
Huffman Compression Appending Header meta-data
MP3 Encoding
MP3 File Structure
MP3 Frame Headers
MP3 Frame Headers
Position Purpose Length
A Frame sync 11
B MPEG audio version (MPEG-1, 2, etc.) 2
C MPEG layer (Layer I, II, III, etc.) 2
D Protection (if on, then checksum follows header) 1
E Bitrate index (lookup table used to specify bitrate for this MPEG version and layer) 4
F Sampling rate frequency (44.1kHz, etc., determined by lookup table) 2
G Padding bit (on or off, compensates for unfilled frames) 1
H Private bit (on or off, allows for application-specific triggers) 1
I Channel mode (stereo, joint stereo, dual channel, single channel) 2
J Mode extension (used only with joint stereo, to conjoin channel data) 2
K Copyright (on or off) 1
L Original (off if copy of original, on if original) 1
M Emphasis (respects emphasis bit in the original recording; now largely obsolete) 2
MP3 Frame Length
Embedding Text into MP3 Files
Non-Stegonographic methods
Encode time mp3 stegonography
Post encoding mp3 stegonography
Non Stegonographic Methods
ID3v2 Comment Frame Lyrics3 Specification (ID3 extension)
Flaws of Non-Stego Methods
Increase in File Size
Not applicable to this project
Encode Time Stegonography
Low Bit Encoding
Phase Coding
Spread Spectrum Coding
Echo Data Hiding
Flaws of Encode Time Stego
Difficult to implement
Tied to single implementation of mp3 encoder/decoder
Require access to source wav files
Post Encoding Stegonography
Unused Header Bit Stuffing
Padding Byte Stuffing
Why Post Encode Stego?
Easy to implement Do not require source WAV files Can be used with an of the shelf
encoder No sound quality degradation
Implementation Choices
Implemented in Java
Stegonographic Method: Padding Byte Stuffing
Stegonographic Module as stand alone application
Stegonographic Module: Design
Flow of Control
LZW Compression
StegIO - Writing calculate the length of the message in bytes prepend the length to the message put the message on a byte queue
while(there are still bytes to be written) {
Header = read 4 bytes from the file
if(Header is_valid && contains padding byte){
seek to the end of framepop the byte from the queuewrite the popped byte into file
} }
StegIO - Reading
length = integer > 4 counter = 0 while (counter < length) {
Header = read 4 bytes from the fileif(Header is_valid && contains padding byte){
if(counter == 4){ length = to_integer ( pop 4 bytes from queue)}seek to the end of frameread a byte from the filepush the read byte onto queue
} }
Stegonographic Module: Usage
To Embed text:
java –jar mp3stego.jar mp3_file.mp3 text_file.txt
To Extract text:
java –jar mp3stego.jar mp3_file.mp3
Stegonographic Module: Comments & Future Work
Padding Byte Stuffing – problematic
Data Corruption
Java and MP3
Java Sound API
Java Media Framework
MP3 Player Implementation
Used an open source java player called Java MP3 player.
http://www.codetoad.com/java_mp3_player.asp
Text & Music Synchronization
Line starts with time offset Followed pipe character “ | ” Followed by the lyric text Line ends with a new line (“ \n ”) File terminates in hash mark (“ # “)
Sample Lyrics File
19100|May the good Lord be with you21250|Down every road you roam28300|And may sunshine and happiness31150|surround you when you're far from home
…
207790|Forever Young217240|For, forever young227050|Forever Young
#
Future Work
Implementation using Unused Header Bit Stuffing
Automating Lyrics Markup and Synchronization
Demo and Questions
References Hacker, Scot, “MP3, The Definitive Guide”, 1st Edition, March 2000, O'Reilly Publishing. Noto, Mark, MP3Stego: Hiding Text in MP3 Files, September 2001, SANS Institute. Koichi Takagi, Shigeyuki Sakazawa, Yashuiro Takishima, “Light Weight MP3 Watermarking Method for
Mobile Terminals”, KDDI R&D Labs, MM'05 November 6-11, 2005 Singapore, ACM “Huffman Code”, Wikipedia, http://en.wikipedia.org/wiki/Huffman_code M. Nilsson, “ID3 tag version 2.4.0 - Main Structure”, November 2000,
http://www.id3.org/id3v2.4.0-structure.txt Predrag Supurovic, “MPEG Audio Frame Header”, 1998 DataVoyage, http://
www.dv.co.yu/mpgscript/mpeghdr.htm#MPEGTAG “The Private Life of MP3 Frames”, http://www.id3.org/mp3frame.html M. Nilsson, “ID3 tag version 2.3.0”, February 1999, http://www.id3.org/id3v2.3.0.html Strnad Peter, Gingold Peter, “Lyrics3 Tag v2.00”, Jun 1998, http://www.id3.org/lyrics3200.html Bender W., Gruhl D., Morimoto N., Lu A., “Techniques for data hiding”, 1996, IBM,
http://www.research.ibm.com/journal/sj/353/sectiona/bender.txt Petitcolas Fabien A. P., “mp3stego”, 1997–2005,
http://www.petitcolas.net/fabien/steganography/mp3stego/ Koso A., Turi A., and Obimbo C., “Embedding Digital Signatures in MP3s”, from proceedings 477
Internet and Multimedia Systems, and Applications, 2005 Cheng Cheok Yan, “Introduction On Text Compression Using Lempel, Ziv, Welch (LZW) method”,
http://www.geocities.com/yccheok/lzw/lzw.html “LZW”, Wikipedia, http://en.wikipedia.org/wiki/LZW “Information-and-Entropy”, MIT, Spring 2003, http://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-
and-Computer-Science/6-050JInformation-and-EntropySpring2003/ABF6E960-C29C-48BB-95AE-AF9F79D9E20B/0/chapter3new.pdf
Fraunhofer-Gesellschaft, http://www.iis.fraunhofer.de/amm/techinf/layer3/index.html
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