PAWAN KR. VERMA(0900410055)
• What is Steganography ?
• Steganography – History
• Watermarking and Cryptography
• Steganography vs. Cryptography
• Steganography vs. Watermarking
• Steganography – Carrier Files
• Modern Steganography Techniques
• Basics of Modern Steganography
• Important Requirement for Steganographic System
• Uses for Steganography
• Steganography – Tools
• Detection of Steganographic Content/Countermeasures
• Existing Steganographic Techniques
• Existing Attacks
What is Steganography ?
Steganography is of Greek origin and means “concealed
• from the Greek word steganos meaning “covered”
• and the Greek word graphie meaning “writing”
Steganography is the process of hiding of a secret
message within an ordinary message and extracting it
at its destination.
Steganography is a technique of hiding information in
The art of detecting Steganography is referred to as
Steganography - History
• Both Axis and Allied spies during World War II used
such measures as invisible inks using milk, fruit juice
or urine which darken when heated.
• It’s also a very good Anti-forensics mechanism to
mitigate the effectiveness of a forensics investigation
• In ancient Greece they used to select messenger &
shave their head, they would then write a message on
their head, once the message had been return the hair
was allowed to grow back after the hair grew back the
messenger was sent to deliver the message, the
recipient would shave off the messengers hair to
seethe secret message
Watermarking and Cryptography
There are two major branches of information hiding, Cryptography and
• 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.
• Doesn’t conceal the communication.
• Scrambles the data to prevent eavesdroppers understanding the
• Cryptography involves various methods and implementations.
• May be considered complementary and orthogonal (unrelated).
Steganography vs. Cryptography
Steganography and cryptography are closely related.
Cryptography scrambles messages so it can’t be understood.
Steganography on the other hand, hide the message so there is
no knowledge of the existence of the message. With
cryptography, comparison is made between portions of the
plaintext and portions of the cipher text. In steganography,
comparisons may be made between the cover-media, the stego-
media, and possible portions of the message. The end result in
cryptography is the cipher text, while the end result in
steganography is the stego-media. The message in
steganography may or may not be encrypted. If it is encrypted,
then a cryptanalysis technique is applied to extract the
Steganography vs. Watermarking
Digital watermarking can be a form of steganography, in which data
is hidden in the message without the end user's knowledge.It is a
technique which allows an individual to add hidden copyright notices
or other verification messages to digital audio, video, or image signals
and documents. Such a message is a group of bits describing
information pertaining to the signal or to the author of the signal
(name, place, etc.) The technique takes its name from watermarking
of paper or money as a security measure.
Modern Steganography Techniques
1. Masking and Filtering: Is where information is hidden
inside of a image using digital watermarks that include
information such as copyright, ownership, or licenses.
2. Algorithms and Transformations: This technique hides
data in mathematical functions that are often used in
3. 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.
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
1. Security of the hidden communication
2. Size of the payload
3. Robustness against malicious and unintentional attacks
Detection of Steganographic
The detection of steganographically encoded packages is
• Visual Analysis tries to reveal the presence of
secret communication through inspection, either
with the naked eye or with the assistance of a
• 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.
DIFFERENT KINDS OF STEGANOGRAPHY
The four main categories of file formats that can be used for
Text steganography: Hiding information in text is the most
important method of steganography. The method was to hide a
secret message in every nth letter of every word of a text message.
After booming of Internet and different type of digital file formats
it has decreased in importance. Text stenography using digital
files is not used very often because the text files have a very small
amount of redundant data.
Text steganography can be classified in three basic Categories:-
• Statistical generation and linguistic method.
Image steganography: Images are used as the popular cover
objects for steganography. A message is embedded in a digital
image through an embedding algorithm, using the secret key. The
resulting stego image is send to the receiver. On the other side, it
is processed by the extraction algorithm using the same key.
During the transmission of stego image unauthenticated persons
can only notice the transmission of an image but can’t guess the
existence of the hidden message.
Audio steganography: Audio stenography is masking,
which exploits the properties of the human ear to hide
information unnoticeably. An audible, sound can be inaudible
in the presene of another louder audible sound .This property
allows to select the channel in which to hide information.
Protocol steganography: The term protocol
steganography is to embedding information
within network protocols such as TCP/IP. We
hide information in the header of a TCP/IP
packet in some fields that can be either
optional or are never used.
The steganographic algorithms can broadly be
classified into two categories :-
1. Spatial Domain Techniques
2. Transform Domain Techniques
Spatial Domain:- These techniques use the pixel gray
levels and their color values directly for encoding the
Transform Domain:- These techniques try to encode
message bits in the transform domain coefficients of the
The steganalytic attacks developed till date can be
classified into visual and statistical attacks.
The statistical attacks can further be classified as :-
• Targeted Attacks: These attacks are designed keeping a
particular steganographic algorithm in mind.
Sample Pair Analysis
HCF-COM based Attack
• Blind Attacks: The blind approach to steganalysis is
similar to the pattern classification problem.
Wavelet Moment Analysis
Calibration Based Attacks
Farid’s Wavelet Based Attack
1. The approach proposed in this work aims at hampering the
steganalysis ability to effectively estimating the statistics for
2. It was found that the calibration step is indeed able to estimate
image model. To counter this a generalized framework has been
proposed which disturbs this model estimation of the attack.
3. It is based on embedding data such that stego population remains
statistically closer to the cover population and the difference between
these two cannot be observed in the statistics drawn from the two
populations and if any how attacker may be able to know the
embedding algorithm but in that case he will not be able to know the
right pattern of the message because we will embed the message in
the form of cipher text.
4. Like this our security will remain consistent. Like this proposed
algo will be successful in breaking calibration based blind attacks.
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