Thái Chí MinhTrần Lương Khiêm
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Content
Introduction History Applications Requirements Techniques Attacks
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Content
Introduction History Applications Requirements Techniques Attacks
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Introduction
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Introduction
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Introduction
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Introduction
Relation between embedded message and cover work
Goal and assumption
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Content
Introduction History Applications Requirements Techniques Attacks
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History
Histiæus & the slave
Paper watermark, 1282
Banknote. 18th century
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History In 1954, Emil Hembrooke of the Muzak Corporation filed a patent for
watermarking” musical Works The first Information Hiding Workshop (IHW) ,which included digital
watermarking as one of its primary topics, was held in 1996
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Content
Introduction History Applications Requirements Techniques Attacks
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Applications
Broadcast monitoring Owner identification Proof of ownership Transaction tracking Content authentication Copy control
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Broadcast monitoring
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Owner identification
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Proof of ownership
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Transaction tracking
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Transaction tracking
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Content authentication
Digital signature is NOT enough
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Content authentication
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Copy control
Cryptography is NOT enough
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Copy control
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Content
Introduction History Applications Requirements Techniques Attacks
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Requirements
Perceptual Transparency Robustness Data payload With / Without originals Security
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Perceptual Transparency
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Robustness
Fragile Semi-fragile Robust
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Data payload
Data payload refers to the number of bits a watermark encodes within a unit of time or within a Work
Different applications may require very different data payloads
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With / Without originals
Non-blind watermarkingType I
Type II
Semi-blind watermarking
Blind watermarking
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Security
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The mutual dependencies among the elements
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Content
Introduction History Applications Requirements Techniques Attacks
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Techniques
LSB Spread spectrum Applying on Vietnamese documents
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Techniques
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Techniques
There are many techniques to do watermarking in digital things:Spatial domain watermarking: LSB, in text
data, …Transform domain watermarking: frequency-
based watermarking, wavelet based watermarking○ Embedding the watermark in the transform
domain from carrier object (using DCT, DFT, DWT, …)
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Techniques
LSB:Embedding:
○ Choosing some representation values (e.g pixels) of carrier object.
○ Embed the bits of message (watermark) to LSBs of representation valueMessage ‘A’: 100 0001Carrier object: RGB (2 bits)
100000 010101 101100
010001 100001 000100
101110 011010 111000
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Techniques
LSB:Embedding:
○ Choosing some representation values (e.g pixels) of carrier object.
○ Embed the bits of message (watermark) to LSBs of representation valueMessage ‘A’: 100 0001Carrier object: RGB (2 bits)
100001 010100 101100
010000 100001 000100
101111 011010 111000
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Techniques
LSB:Detector:
○ Retrieve the watermark by having the knowledge of the representation values (e.g pixels) used for embedding individuals bits
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Techniques
Spread spectrumUsing frequency domain transform to
convert the input image into another domain and embedding the watermark to this domain.
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Techniques
• Apply on Vietnamese documents
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Techniques
• Apply on Vietnamese documents
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Techniques
• Apply on Vietnamese documents○ Besides, we can use some methods:
Vertically shifting text lines Horrizontally shifting words
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Content
Introduction History Applications Requirements Techniques Attacks
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Attacks
From processing From attackers
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Attacks
The actions take effect on the watermark embedded in carrier objects.Affects:
○ Destroying the watermark or modifying the watermark with new wrong information.
○ Removing the watermark entirely.But: not degrading the quality of carrier
objects (image, audio, video)Relating to a requirements of watermarking:
Robustness
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Attacks Classification:
From proscessing carrier objects○ Common signal processing: digital-to-analog and
analog-to-digital conversion, or change image contrast, color, JPEG compression, …
○ Common geometric distortions: scaling, rotating, cropping, dithering …
From attacker○ Mosaic○ Collusion attacks: get the watermark or remove
watermarks entirely to get the original work.○ …
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Attacks
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AttacksMosaic attack
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Attacks How to protect watermarks from attacks
Understanding and applying new researchs in watermarking
Using StirMark Benchmark evaluation engine to evaluate your watermarking scheme○ “All vendors of digital watermarks have their
products benchmarked by Stirmark and as of August 2001, no watermark from any vendor survives the test, ie: the watermarks are all removed without degradation to image quality occurring. “
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