Second Quarter
Implementation of Least
Significant Bit Image
Steganography and its
Steganalaysis
Goals
• To conceal either an image or a text message into a
"carrier" image with Least Significant Bit
Steganography
• To detect that an image has been compromised or
altered
• To extend the method to apply to various image formats
• To make the program usable with a Graphical User
Interface (GUI)
What is Steganography?
• Literally means "concealed writing" in Greek
• Opposite of cryptography, in which a message is made
unintelligible, but transmitted through public means
• Steganography is the concealment of the fact that
a message is even being transferred.
Historical Methods
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Shaving hair
Wax tablets
Jargon
Cardano grille
Invisible Inks
Thermo-activated inks
Micro dots
Enigma Machine
All of the above have been used for espionage and
for coordinating attacks on other bodies.
Current Method
• Hiding an entire text or image binary in either an image or
audio “carrier” using Least Significant Bit encoding
• Previously done as a Senior Technology Lab using the
same technique with .wav audio files in 2007.
• There is currently no established method for encoding
something with steganography because better encoding
methods translate to lower carrier image capacity.
• There is no established method for universally detecting
steganography because of the variety of methods.
Least Significant Bit Encoding
• Images on computers are made out of pixels
• Each pixel is represented by three bytes
• Each byte is composed of eight bits or 1s and 0s
10010101 00001101 11001001 10010110
00001111 11001011 10011111 00010000
10010100 00001101 11001000 10010110
00001110 11001011 10011111 00010001
• The second set of bytes represents the encoded
ASCII character “G” (01000111)
Program Design in JAVA
• Create a GUI
• Dropdown menu
• Input a suspected image
• Attempt to detect if it has
been compromised
• Place the two image next to
each other for visual
comparison.
Inputing the Image
•Read the binary of the image using Buffered Reader,
DataBufferByte, and Writable Raster into a three
dimensional array (datacube) with row, column, and
corresponding color value (depends on image format ).
•Alter every Least Significant Bit in each byte in order to
spell out the word. Each ASCII character's binary are
understood by DataBuffer ByteSave the altered image
because it is ready to be sent
•Saving should be done using a “lossless” image standard
because this form of steganography exploits the “noise”
of an image. Therefore, .PNG is a good start.
Steganalysis
• Detecting a message encoded using steganography is
only feasible if the original image is available or if the
exact encoding method is known.
• The program will still be able to detect if an image has
been compromised by converting the suspected image
into hexadecimal but the message may not be extracted.
• Each image format has a specific tag associated with it
at a specific part of the hexadecimal code (this won't
work if a proper LSB is done).
Image Hex Tags
Image Format Tag of Compromised Location Within the
File
Hex Code
.GIF
47 49 46 38
Beginning
.JPG
FF D9
End
.PNG
89 50 4E 47 0D 0A
1A 0A 00 00 00 0D
49 48 44 52
Beginning
Detection
• Read the suspected image's binary into a text file
• Convert the binary code into hexadecimal
• Find the supposed image format of the suspected image
• Test if its associated hexadecimal tag is legitimate
• OR
• Just attempt to reverse the process of Least Significant
Bit encoding. This method is always tried by commercial
software but hardly works if the LSB is done differently.
Possible Problems
•Steganography is an increasingly complex field because
of new algorithms
•There are many methods to inconspicuously hide an
image or text message with computer science, some are
less complex (microdots) and some use higher level
mathematical algorithms (stochastic modulation)
•The Least Significant Bit method is an established
method and will be probably be detected by commercial
Steganalysis software, but not the human eye
Testing
• Tests involve inserting a character into an image,
finding where the character is hidden, and verifying that it
is indeed the letter. Tests on file size versus message
length should be done. A visual comparison is required:
Testing Continued
•Binary comparison revealed that after 32 bytes there was
a variation when the letter “G” (01000111) was encoded:
Original: 01110011 11100001 01101100 00111000
01100010 0101000 00100010 00101010
•Altered: 00001110 11000011 00000000 00000000
00001110 11000011 00000001 11000111
•There was also testing on the rendering time of the
image. The rendering appeared to be a linear trend.
Learned Concepts
• How images of various formats are constructed (.PNG)
• How to manipulate binary code and understanding the
role of bits within bytes. Binary operations such as AND,
OR, and addition.
• Various methods of Steganography and Steganalysis and
which are the most effective
• How to determine a file's extension using JAVA
Future Plans
• Since encoding now works for the .PNG format, the
extraction still needs work (getting it to run properly).
• Detect the image format with JAVA as opposed to
manually inspecting the Hex code.
• Encode images into the program.
• Extend the program to work with other image formats
and improve the algorithms susceptibility to common
detection methods (using padding and random byte
locations).