steganography brief description

1. Made by :
Manika Arora

2. What is Steganography?
• Steganography is the art and science of writing hidden
messages in such a way that no one, apart from the
sender and intended recipient, suspects the existence of
the message, a form of security through obscurity.
• The word steganography is of Greek origin and means
"concealed writing" from the Greek
words steganos meaning "covered or protected",
and graphein meaning "writing".
• “Steganography means hiding one piece of data
within another”.

3. Typical Scenario

4. Example
Since everyone can read, encoding text
in neutral sentences is doubtfully effective
Since Everyone Can Read, Encoding Text
In Neutral Sentences Is Doubtfully Effective
‘Secret inside’

5. History Of Steganography
• Dates back to 400 BC when Histaeus sent a message, by
shaving the head of his most trusted slave, then tattooed a
message on the slave's scalp, to his friend Aristagorus, urging
revolt against the Persians.
• Demaratus tells Athens of Persia’s attack plans by writing the
secret message on a tablet, & covers it with wax.
• Chinese wrote messages on silk and encased them in balls of
wax. The wax ball, "la wan," could then be hidden in the
messenger.
• A more subtle method, nearly as old, is to use invisible
ink( lemon juice, milk, or urine, all of which turn dark when held
over a flame).
• Special “inks” were important steganographic tools even during
Second World War.

6. Modern steganography
• Hiding one message within another(“container”)
• Most containers are rich media
Images, audio, video are very redundant, can be tweaked without
affecting human eye/ear
US argued that Al_QAIDA implanted instructions within taped
interviews.
• Copyright notices embedded in digital art
Prove ownership(Watermarking)
Serial number embedded to prevent replication
Seek infringements on the web using spiders/crawlers
• Digital cameras EXIF(Exchangeable Image File Format) tags
Not secretive but hidden from the eye
Embed info such as camera type, date, shutter speed, focal length..
• Similarly, possible to embed messages in invisible part of html
pages

7. Physical techniques
• Physical Techniques Hidden messages within wax
tablets
a) Hidden messages on messenger's body
b) Hidden messages on paper written in secret inks
c) Messages written in Morse code on
knitting yarn and then knitted into a piece of
clothing worn by a courier
d) Messages written on envelopes in the area
covered by postage stamps.

8. Digital technique
• Digital Techniques
a) Concealing messages within the lowest bits
of noisy images or sound files.
b) Modifying the echo of a sound file (Echo
Steganography)
c) Including data in ignored sections of a file, such
as after the logical end of the carrier file.

9. Comparison Of Secret Communication
Techniques

10. Evolution
Cryptography
Steganography
Watermarking

11. Steganography V/s Cryptography

12. Steganography Terms
• Carrier or Cover File - A Original message or a file in
which hidden information will be stored inside of it .
• Stego-Medium - The medium in which the information is
hidden.
• Embedded or Payload - The information which is to be
hidden or concealed.
• Steganalysis - The process of detecting hidden
information inside a file.

13. Basic Steganography Model

14. Types of steganography
• Steganography In text/documents
• Steganography In images
• Steganography In audio
• Steganography in video

15. Text Steganography
• Text steganography can be applied in the digital makeup format
such as PDF, digital watermark or information hiding
• It is more difficult to realize the information hiding based on
text. The simplest method of information hiding is to select the
cover first, adopt given rules to add the phraseological or
spelling mistakes, or replace with synonymy words.
• E.g 1] Textto setups some sentence structure in advance, fills
in the empty location by arranged words,
and then the text doesn’t have phraseological mistakes, but
have some word changes or morphology mistakes.
2] TextHide hides the information in the manner of text
overwriting and words’ selection.

16. Examples of Text Steganography
• An example of a message containing cipher text by
German Spy in World War II:
“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. ”
• Taking the second letter in each word the following
message emerges:
Pershing sails from NY June 1.

17. Examples of Text Steganography
• Minor changes to shapes of characters

18. Examples of text Steganography

19. Image Steganography
• Using image files as hosts for steganographic messages
takes advantage of the limited capabilities of the human
visual system
• Some of the more common method for embedding
messages in image files can be categorized into two main
groups, image domain methods and transform domain
methods

20. Image And Transform Domain
• Image – also known as spatial – domain techniques
embed messages in the intensity of the pixels directly,
while for transform – also known as frequency – domain,
images are first transformed and then the message is
embedded in the image
• Image domain techniques encompass bit-wise methods
that apply bit insertion and noise manipulation and are
sometimes characterised as “simple systems”
• Steganography in the transform domain involves the
manipulation of algorithms and image transforms

21. Example of image Steganography
Fig:Image in hex editor

22. Audio Steganography
• Embedding secret messages into digital sound is
known as audio Steganography.
• Audio Steganography methods can embed
messages in WAV, AU, and even MP3 sound
files.
• The properties of the human auditory system
(HAS) are exploited in the process of audio
Steganography

23. Flowchart Of Audio Steganography

24. Example of LSB Method
• The message 'HEY' is
encoded in a 16-bit CD
quality sample using the LSB
method.
• Here the secret information is
‘HEY’ and the cover file is
audio file. HEY is to be
embedded inside the audio
file. First the secret
information ‘HEY’ and the
audio file are converted into
bit stream.
• The least significant column
of the audio file is replaced by
the bit stream of secret
information ‘HEY’. The
resulting file after embedding
secret information ‘HEY’ is
called Stego-file.

25. Steganalysis
• The art and science of steganalysis is intended to detect or estimate
hidden information based on observing some data transfer.
• In some cases, just being caught sending a message can bring
suspicion, or give information to the 3rd party
• Steganalysis techniques can be classified in a similar way as
cryptanalysis methods, largely based on how much prior information
is known.
Steganography-only attack: The steganography medium is the only
item available for analysis.
Known-carrier attack: The carrier and steganography media are
both available for analysis

26. Steganalysis
 Known-message attack: The hidden message is known.
Chosen-steganography attack: The steganography medium and
algorithm are both known.
Chosen-message attack: A known message and steganography
algorithm are used to create steganography media for future
analysis and comparison.
Known-steganography attack: The carrier and steganography
medium, as well as the steganography algorithm, are known
discipline with few articles appearing before the late 1990s.

27. Steganography Tools
1. Hide in Picture
2. TextHide
3. Snow
4. Camouflage
5. OpenPuff

28. Advantages
• Difficult to detect and Only receiver can detect.
• It can be done faster with large no. of software's.
Disadvantage
• The confidentiality of information is maintained by the
algorithms, and if the algorithms are known then this
technique is of no use.
• Password leakage may occur and it leads to the
unauthorized access of data.
• If this technique is gone in the wrong hands like hackers can
be very much dangerous for all.

29. Applications
• Confidential communication and secret data
storing
• Steganography provides us with:
• Potential capability to hide the existence of
confidential data
• Hardness of detecting the hidden (i.e.Strengthening
of the secrecy of the encrypted data)
• Protection of data alteration

30. Applications
• Usage in modern printers
• Access control system for digital
content distribution
• Alleged use by terrorists
• Alleged use by intelligence services

31. Who’s Using It?
• Good question… nobody knows for sure.
• The whole point to steganography is to disguise its use.
• However, anybody can use it to hide data or to protect
anonymity
• Likely users include:
a) Trade fraud
b) Industrial espionage
c) Organized crime
d) Narcotics traffickers
e) Child pornographers
f) Criminal gangs
g) Individuals concerned about perceived government “snooping”
h) Those who want to circumvent restrictive encryption export rules
i) Anyone who wants to communicate covertly and anonymously

32. Detection
• Can steganography be detected?
• Sometimes…many of the simpler steganographic
techniques produce some discernable change in the file
size, statistics, or both. For image files, these include:
• Color variations
• Loss of resolution or exaggerated noise
• Images larger in size than that to be expected
• Characteristic signatures, e.g., distortions or patterns
• However, detection often requires a priori knowledge of
what the image or file should look like

33. Detection Challenges
• Lack of tools and techniques to recover the
hidden data
• No commercial products exist for detection
• Custom tools are analyst-intensive
• Few methods beyond visual analysis of graphics
files have been explored
• Usually, no a priori knowledge of existence
• No access to stegokey
• Use of unknown applications

34. Need for Improved Detection
• Growing awareness of data hiding techniques and uses
• Availability and sophistication of shareware and freeware
data hiding software
• Concerns over use to hide serious crimes, e.g., drug
trafficking, pedophilia, terrorism
• Frees resources currently spent on investigating cases
with questionable/unknown payoff
• Legislative calls
• US Bill H.R. 850, Security and Freedom through Encryption (SAFE)
Act
• UK Revision of Interception of Communications Act 1985

35. Future Scope
• Steganography, though is still a fairly new idea. There are
constant advancements in the computer field, suggesting
advancements in the field of steganography as well. It is likely
that there will soon be more efficient and more advanced
techniques for Steganalysis. A hopeful advancement is the
improved sensitivity to small messages. Knowing how difficult it
is to detect the presence of a fairly large text file within an
image, imagine how difficult it is to detect even one or two
sentences embedded in an image! It is like finding a
microscopic needle in the ultimate haystack.
• What is scary is that such a small file of only one or two
sentences may be all that is needed to commence a terrorist
attack. In the future, it is hoped that the technique of
Steganalysis will advance such that it will become much easier
to detect even small messages within an image.

36. Conclusion
• Steganography & Steganalysis are still at an early stage of
research.
• Although in principle secure schemes exist, practical ones with
reasonable capacity are known.
• Notion for security & capacity for steganography needs to be
investigated.
• Since it obvious that no system of data hiding is totally
immune to attacks. However, steganography has its place in
security. It in no way can replace cryptography, but is
intended to supplement it. Its application in watermarking for
use in detection of unauthorized, illegally copied material is
continually being realized and developed.
• The growing number of communication protocols, services
and computing environments offers almost unlimited
opportunities for displaying a whole spectrum of
steganographic methods.