Transcript Steganography - University of Central Florida

An Enhanced Steganographic Method
for Data Hiding in
Microsoft Word Documents by a
Change Tracking Technique
Dan DeBlasio and Brad Mundt
University of Central Florida
[email protected], [email protected]
Steganography
What is Steg?
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The word steganography is of Greek origin
and means "covered, or hidden writing".
Modern implementation is embedding secret
information into something innocent
Pictures, audio, video
Picture Steg
Image of a tree.
By removing all but the last 2
bits of each color component, an
almost completely black image
results. Making the resulting
image 85 times brighter results
in the image to the right.
Image extracted from
tree image.
Our selection
A New Steganographic Method for Data Hiding in
Microsoft Word Documents by a Change Tracking
Technique by Tsung-Yuan Liu and Wen-Hsiang Tsai
A new steg method to hide information via MS Word
change tracking
Collaborative document with corrections
Deleted words are struck through and new words are
underlined
Overview
Transform a regular document to one with
misspellings or mistakes
Make changes, allow word to track them.
Using a Huffman tree on the original words in
the file, create a binary string of the embedded
message
Decode the binary string to get the secret
message
Original sentence
The quick brown fox jumped over the lazy dog.
Sentences with Misspellings
The quick borwn fox jumped oevr the lazy dag.
Sentence with changes tracked
The quick borwnbrown fox jumped oevrover the lazy dagdog.
Huffman Tree
Created from the
frequency of
misspellings
Word
teh
qwik
borwn
broun
jumpped
oevr
orver
dag
Huffman
11
101
10010
0011
000010
0001110
100010
01
How to Decode
The quick borwnbrown fox jumped oevrover the lazy dagdog.
Word
teh
qwik
borwn
broun
jumpped
oevr
orver
dag
Huffman
11
101
10010
0011
000010
0001110
100010
01
1001000 0111001
0x72 0x105
Hi
Our implementation
Recreated the method from scratch
Made improvements
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Modular code for easy improvements
Encryption, simple XOR pad with key in the
author field
Example next,
then a live demo
A Word document
Before steg encoding
Encoding in Progress
Encoding Complete
The Word document
After steg encoding
Decoding in Progress
Decoding complete
Live Demo
Statistical Results
Changes
Document 1 40.4
Document 2 43.2
Bits
93.8
99.8
b/change
2.321
2.310
Document 3 65.6 129.6 1.976
Document 4 124.4 224.8 1.968
Document 5 37.6 78
2.074
Words
%
changed
Sent.
Changes/Sent
475
551
8.5%
7.8%
29
31
1.393
1.394
641
1268
481
10.2% 51
9.8% 89
7.8% 27
1.286
1.398
1.392
Improvements
Due to the code being modular, improvements
will be easy
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More advanced or alternate encryption algorithms
Implement a Markov model instead of a Huffman tree
for statistical attacks
Use synonyms instead of misspellings or a
combination of both
That’s all for now folks!