Information System Security
AABFS-Jordan
Summer 2006
Watermarking
Presented To: Dr. Lo'ai Tawalbeh
Prepared By: Sami Qawasmeh
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Outline
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Information Hiding overview
Introduction: History , Definition, and Motivation
Watermarking Classification : Paper and Digital WM
Desired Properties of Watermark
Digital Watermarking Types
Watermarking Process – Embedding and Extraction.
Watermarking Techniques
Watermarking Attackers and Attacks
Limitations and Conclusions
Future Researches
References
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What is Information Hiding?
 Classical: Embedding information so that it
cannot be visually perceived
 Modern : Embedding information in digital data so
that it cannot be visually or audibly perceived
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Why Hide Information?
There are two major issues
 Because you want to protect it from malicious use
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protect intellectual property rights(IPR)
 Because you do not want any one to even know
about its existence
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Avoid observation by unintended recipients
“Security through obscurity”
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Information Hiding Main Disciplines
 Steganography- (covered writing) the process of
secretly embedding information into a data source
in such a way its very existence is concealed.
 Watermarking:
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Definitions
 Watermark : is a “secret message” that is
embedded into a “cover message”.
 Digital watermark: is a visible or perfectly invisible,
identification code that is permanently embedded
in the data and remains present within the data
after any decryption process.
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History
 The Italians where the 1st to use watermarks in the
manufacture of paper in the 1270's.
 A watermark was used in banknote production by the
Bank of England in 1697.
It is a good security feature because the watermark
cannot be photocopied or scanned effectively.
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Why Watermark? Motivation (1/2)
 The rapid revolution in digital multimedia and the ease of
generating identical and unauthorized digital data.
For example: USA Today, Jan. 2000: Estimated lost
revenue from digital audio piracy $8,5 billions
 Digital objects can be copied and distributed, transmitted,
manipulated anonymously with no way to identify the
criminals.
 Copyright protection of multimedia data

Copyright owners want to be compensated every time
their work is used.
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Why Watermark? Motivation (2/2)
 The need to limit the number of copies created whereas
the watermarks are modified by the hardware and at
some point would not create any more copies (i.e. DVD)
- the reading device must be able to modify the watermark
 Content protection – content stamped with a visible
watermark that is very difficult to remove so that it can
be publicly and freely distributed
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Watermarks Classification
1. Paper Watermark: Intended to be somewhat visible.
2. Digital Watermark: A digital signal or pattern imposed on
a digital document ( text, graphics, multimedia
presentations , …
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Paper Watermark
The technique of impressing into the paper a form,
image, or text.
“Cannot be photocopied or scanned effectively”
Purpose: To make forgery more difficult to record
the manufacturer’s trademark, Copyright
protection, logos, ect …
Used in :
Currency, Banknotes , Passports, …
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Paper watermark
Example
Some Digital Watermarking Types (1/2)
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Visible vs. Invisible:
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Visible such as a company logo stamped on an image or
Video.
 Invisible intended to be imperceptible to the human eye
or inaudible. the watermark can only be determined through
watermark extraction or detection by computers.
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Fragile vs. Robust :
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Fragile watermarks break down easily.
 Robust survive manipulations of content.
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Some Digital Watermarking Types (2/2)
●
Public vs. private – Private watermarking techniques
require that the original be used as a basis of
encryption whereas public does not
●
Public-key vs. secret-key – Secret-key
watermarking uses the same watermarking key to read
the content as the key that was inserted into the image;
public key uses different keys for watermarking the
image and reading the image
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Some Desired Properties of (DW) ( 1/3)
1. Robustness
2. Tamper Resistance
3.
Economically Implementable
4. Unambiguous
5. Capacity
6. Quality
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Desired Properties ( 2/3)
(1) Robustness: A watermark must be difficult or
impossible to remove, at least without visibly
degrading the original image. A watermark must
survive image modifications.
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Geometric distortions: rotation, scaling, translation, etc.
(2) Tamper Resistance: The watermark must resist any
type of attacks, what ever the intentions are: remove
or modify
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Desired Properties ( 3/3)
(3) Economically implementable: Time and
effort, cost.
(4) Unambiguous: The watermark, when
retrieved, should unambiguously identify the
owner.
(5) Capacity: The amount of information that can be
embedded
(6) Quality: (High Quality) - Quality not degraded
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Properties Tradeoff
Robustness
Quality
Capacity
Embedding and Extraction Complexity
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Important Definitions
 Cover : Audio-video, text in which data will be hidden
 Watermark: What is actually added to the cover
 Information: message to be added
 Watermarking key: Secret parameter needed for
embedding & detecting the watermark & extracting the
information
 Watermarking Function: Embedding & Extraction
algorithms.
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Watermarking Process
 Two major steps:
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Location Selection : Where to embed watermark
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Processing : How to modify original data to
embed watermark
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Watermarking Embedding &
Extraction
Cover Image
Cover + WM
Cover + WM
Embedding F : Watermarked Image = Function (Cover, Watermark, Key)
Extraction F : Watermark = Function (Watermarked Image, Key(
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Watermarking Techniques
 Text – Varying spaces after punctuation, spaces in
between lines of text, spaces at the end of
sentences, etc.
 Audio – Low bit coding, random.
 Images / Video – Least-significant bit, random
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Text Watermarking
Techniques: Varying spaces after punctuation, spaces in
between lines of text, spaces at the end of sentences,
etc.
Examples:
 Line Shift Coding : Shift every other line up or down
slightly in order to encode data
 Word Shift Coding: Shifts some words slightly left or
right in order to encode data
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Image Watermarking / LSB
LSB: Using the least significant bits of each pixel in
one image to hide the most significant bits of
another.
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Pixels may be chosen randomly according to a
key
Steps:
1.
2.
3.
Load up both the host image and the image you
need to hide.
Chose the number of bits you wish to hide the
secret image in.
Combine the pixels from both images
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LSB - Example
0
0
1
1
1
1
0
0
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1
0
0
0
0
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0
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1
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0
1
1
0
1
0
0
1
0
1
1
0
1
0
0
1
0
1
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0
1
0
0
1
0
1
0
1
0
0
0
0
1
0
0
0
1
1
1
1
0
0
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Audio Watermarking
 Low Bit Coding
 Echo Data Hiding
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Audio Watermarking
 Low Bit Coding
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Most digital audio is created by sampling the signal
and quantizing the sample with a 16-bit quantizer.
The rightmost bit, or low order bit, of each sample
can be changed from 0 to 1 or 1 to 0
This modification from one sample value to another
is not perceptible by most people and the audio
signal still sounds the same
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Audio Watermarking
 Echo Data Hiding
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Discrete copies of the original signal are
mixed in with the original signal creating
echoes of each sound.
By using two different time values between
an echo and the original sound, a binary 1 or
binary 0 can be encoded.
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Video Watermarking
 Video sequences consists of a series of consecutive
and equally time-spaced (Frames) still images
in general, very similar with image watermarking so,
image watermark method is applicable to video directly
Video watermark imposes real or near real-time
watermarking system
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Attackers Main Goal
Attackers seek to destroy watermark for the
purposes of use without having to pay royalties
to the originator of the content.
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Why do we need to study attacks?
Identify weakness
 Propose improvement – Security
 Attackers are knowledgeable, creative, have
lots of time, and are numerous
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Attacks on Watermarking
Two Sets of Attacks
 Unintentional
All image manipulations commonly used to
prepare images for print publication. For
example:
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Resizing, rotation, sharpening, contrast
modification, compression, ect.
 Intentional (Malicious)
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All the well-known intentional attacks include:
Disabling, altering, embedding new watermark, ect.
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Intentional Watermark Attacks (1/2)
 Active Attacks
– hacker tries to remove the watermark
or make it undetectable. Applying Geometric
transformation: rotation, scaling, translation, change
aspect ratio.
 Passive Attacks – hacker tries to determine whether
there is a watermark and identify it. However, no
damage or removal is done.
 Collusion Attacks – hacker uses several copies of one
piece of media, each with a different watermark, to
construct a copy with no watermark.
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Intentional Watermark Attacks (2/2)
 Forgery Attacks – Attacher tries to embed a valid watermark of
their own rather than remove one.
 Conspiracy Attacks : several conspirators, each of whom has
procured a copy of the same image (differing only in the
watermark which is unique to each copy).
 Presentation Attacks: Watermark detection failure. Geometric
transformation, rotation, scaling, translation, change aspect ratio,
etc.
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Limitations / Conclusions
 Rapidly growing field of digitized images, video and audio has
urged for the need of protection.
 Watermarking is a key process in the protection of copyright
ownership of electronic data (image, videos, audio, ...).
 Digital watermarking does not prevent copying or distribution.
 Digital watermarking alone is not a complete solution for
access/copy control or copyright protection.
 Digital watermarks cannot survive every possible attack.
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Challenges in Watermarking Research
 Watermark survival for all types of attacks –
intentional and unintentional.
 Embedding a Color image watermarking
 Multiple layers watermark that aim to protect
each other from being analyzed -The more
robust and reliable the implementation is, the
longer it will last.
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References
1.
M. Kutter, S. Voloshynovskiy and A. Herrigel, The watermark Copy Attack,
Security and Watermarking of Multimedia Contents, II, SPIE-3971: 371-280,
2000.
2.
S. Craver, N. Memon, B.-L. Yeo, and M. Yeung. Resolving rightful
ownerships with invisible watermarking techniques: Limitations, attacks
and implications. IEEE Trans. on Selected Areas of Communications,
16(4):573–586, 1998.
3.
I. Cox, J. Kilian, F. T. Leighton, and T. Shamoon. Secure spread spectrum
watermarking for multimedia. IEEE Trans. on Image Processing,
6(12):1673–1687, 1997.
4.
I. J. Cox and J.-P. Linnartz. Some general methods for tampering with
watermarks. IEEE Trans. on Selected Areas of Communications, 16(4):587–
593, 1998.
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References
http://www-nt.e-technik.uni-erlangen.de/~su/seminar
/ws99/slides/su.pdf
6. http://www.compris.com/TextHide
7. http://www.infosyssec.com/infosyssec/Steganography/
watermarkingAttack.htm
8. http://www.lnt.de/~hartung/ProcIEEEHartungKutter.pdf
9. http://www.watermarkingworld.org
10. http://wwwstu.hatii.arts.gla.ac.uk/Courses/digitisation
11. http://www.inria.fr/Watermarking
12. http://www.isg.rhul.ac.uk/msc/teaching/opt5/archive/20
02-03/slides/watermarking.pdf
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5.
Thanks for your kind attention
any Comments
???
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