oExamples in History
oReasons For Using Digital Images
oPopular Techniques That Use Images
oAdvancements in image steganography
oGreek for “covered writing”.
o“The art and science of writing hidden messages
in such a way that no one apart from the intended
recipient even knows that a message has been
oTattoos on shaved heads
oInvisible Inks - milk, fruit juice
oSteganography involves the hiding of the data while
Cryptography involves the encryption and decryption
oSteganalysis involves finding out whether there is
really a hidden message or not while Cryptanalysis
involves breaking of the encrypted into decrypted
oVery very strong when combined.
oA message sent in secret (steganography) in an
encrypted form (cryptography) is much more secure
than a "plain text" message sent by secret means or a
clearly sent encrypted message.
oToday, it often exists within digital formats.
oIt makes use of seemingly innocent cover files
such as text, audio, and image files.
oThe embedded message may be anything that can
be encoded in binary.
oIt is the most widely used medium being used today.
oTakes advantage of our limited visual perception of
oThis field is expected to continually grow as
computer graphics power also grows.
oMany programs are available to apply
oDigital images are made up of pixels.
o8-bit and 24-bit images are common.
oThe larger the image size, the more information you
can hide. However, larger images may require
compression to avoid detection.
oLeast Significant Bit Insertion
oMasking and Filtering
oReplaces least significant bits with the message
to be encoded.
oMost popular technique when dealing with
oSimple, but susceptible to lossy compression and
LSB - Example
A sample raster data for 3 pixels (9 bytes)
00100111 11101001 11001000
00100111 11001000 11101001
11001000 00100111 11101011
00100111 11101000 11001000
00100110 11001000 11101000
11001000 00100110 11101011
oBest to use a grayscale palette or one with gradual
changes in shades.
oOtherwise, it is best to use images with “noisy areas”
– areas with ample color variation.
LSB - Uses
oStoring passwords and/or other confidential
oCovert communication of sensitive data.
oSpeculated uses in terrorist activities.
oBeing widely used to hide and/or transfer illegal
MASKING & FILTERING
oMasks secret data over the original data by
changing the luminance of particular areas.
oDuring masking, it embed the message within
significant bits of the cover image.
oNot susceptible to lossy techniques because image
manipulation does not affect the secret message.
MASKING & FILTERING
oDigital Watermarking – provides identification
pertaining to the owner; i.e. license or copyright
o Fingerprinting – provides identification of the user;
used to identify and track illegal use of content.
Five classes of steganalysis:
o Chosen-stego and
oUse of steganography for malwares to embed it in
crafted HTML and JPEG files.
e.g. Duqu worm (2011)
oAccording to recent report(30th Jan, 2012), it will be
used in android applications to send premium rates
oSelecting multiplayers’ games to use as a covert
oUse of private chat rooms as a carrier.
oResearch are being done to practice steganography
using a key not by using a method.
Limitations due to these three properties which work
in opposition to each other:-
oCAPACITY of the cover object.
oUNDETECTABILITY of the stego-object.
oROBUSTNESS of the stego-object.
oStrength often depends on attackers not knowing
how data could be hidden.
oSteganography as a whole has existed in many forms
throughout much of history.
oLossless compression of images with a great deal of
color variation work best as a cover image to embed a
oSteganography can be used as beneficial tool for
oSteganography will work best if combined with
lbDEmNM for techniques of steganography
CERIAS Steganography by John Oritz youtube
for watermarking techniques.