Steganography
Khan, Mohammed Minhajuddin
What is Steganography?
Greek Words:
STEGANOS – “Covered”
GRAPHIE – “Writing”
Steganography is the art and science
of writing hidden messages in such a
Stegosaurus: a covered lizard
way that no one apart from the
(but not a type of cryptography)
intended recipient knows of the
existence of the message.
This can be achieve by concealing the
existence of information within
seemingly harmless carriers or cover
Carrier: text, image, video, audio, etc.
Steganography, Cryptography, and
Watermarking
There are two major branches of information hiding, Steganography
and Watermarking
Watermarking:
Communication in watermarking is the host signal, with the
embedded data providing copyright protection.
The existence of a watermark is often declared openly.
Any attempt to remove or invalidate the embedded content
renders the host useless.
Cryptography:
Doesn’t conceal the communication.
Scrambles the data to prevent eavesdroppers understanding
the content.
Cryptography involves various methods and implementations.
May be considered complementary and orthogonal (unrelated).
Once the presence of hidden information is revealed or even
suspected, the purpose of steganography is defeated.
History of Steganography
Steganography ancient origins can be traced back to 440 BC, from the Histories of Herodotus
Demeratus sent a warning about a forthcoming attack to Greece by writing it on a
wooden panel and covering it in wax.
Histiaeus, who shaved the head of his most trusted slave and tattooed a message on it.
After his hair had grown the message was hidden. The purpose was to instigate a revolt
against the Persians.
World War II
Invincible inks
Null ciphers (unencrypted messages):
Apparently neutral's protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects
pretext for embargo on by products, ejecting suets and vegetable oils.
Sent by a German Spy in WWII, by taking the second letter in each word the following
message emerges:
Pershing sails from NY June 1.
Microdot Technology
Shrinking messages down to the size of a dot became a popular method. Since the
microdot could be placed at the end of a sentence or above a j or an i.
Modern Steganography Techniques
Masking and Filtering: Is where information is hidden inside of a image
using digital watermarks that include information such as copyright,
ownership, or licenses. The purpose is different from traditional
steganography since it is adding an attribute to the cover image
thus extending the amount of information presented.
Algorithms and Transformations: This technique hides data in
mathematical functions that are often used in compression
algorithms. The idea of this method is to hide the secret message
in the data bits in the least significant coefficients.
Least Significant Bit Insertion: The most common and popular method
of modern day steganography is to make use of the LSB of a
picture’s pixel information. Thus the overall image distortion is
kept to a minimum while the message is spaced out over the pixels
in the images. This technique works best when the image file is
larger then the message file and if the image is grayscale.
Basics of Modern Steganography
fE: steganographic function "embedding"
fE-1: steganographic function "extracting"
cover: cover data in which emb will be hidden
emb: message to be hidden
key: parameter of fE
stego: cover data with the hidden message
Important Requirement for
Steganographic System
Security of the hidden communication
size of the payload
Robustness against malicious and
unintentional attacks
Steganography Tools
Detection of Steganographic
Content/Countermeasures
The detection of steganographically encoded
packages is called Steganalysis.
Visual Analysis tries to reveal the presence of
secret communication through inspection,
either with the naked eye or with the
assistance of a computer.
Statistical (Algorithmic) Analysis reveals
tiny alterations in an image's statistical behavior
caused by steganographic embedding.
The nominally universal methods developed to detect
embedded stego-data are generally less effective
than the steganalytic methods aimed at specific types
of embedding.
Steganography Sample Website
Here is the link for Sample Steganographic
tool Website:
http://mozaiq.org/
My Questions
1. Salutations, Mr. Robertson of CIS 5371.
The Florida Society of Math and
Cryptography is proud to present you with
an small exam for qualification into our
society. The key for passing is studying.
Cryptography is rigorous and only those
with patience in themselves pass. We have
an exam PO Box in Tallahassee. But please
submit by 12/12.
Answer
Salutations, Mr. Robertson of CIS 5371. The
Florida Society of Math and Cryptography
is proud to present you with an small
exam for qualification into our society.
The key for passing is studying.
Cryptography is rigorous and only those
with patience in themselves pass. We have
an exam PO Box in Tallahassee. But
please submit by 12/12.
The Cryptography exam key is in PO Box 1212.
My Questions
2. Name three methods by which
Modern day Steganography is
accomplished?
Answer:
Masking and Filtering
Algorithms and Transformations
Least Significant Bit Insertion