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Introduction to Multimedia Security Topics Covered in this Course
Multimedia Security
2
Digital Rights Management
Course Coverage
Digital Watermarking
MultimediaCryptography
DRM Standards
DRM Laws
Rights Languages
Steganography/ Steganalysis
Digital Forensics
Biometrics
Multimedia Security
Privacy-Preserving
Data Mining
3
Steganography
• Steganography=“Cover” + “Writing”– The art of hiding information in ways that prevent the detection of hidden
messages– Transmitting secret messages through innocuous cover carriers in such a
manner that the existence of the embedded message is undetectable• Examples
– Invisible inks, character arrangement, covert channels…
Examination
..oxx..
Cover Message
Heating
!!!
Genuine Message + Cover Message
Examination
..oxx..
Paper
..o xx..
Paper withMessages
Genuine Message
..o xx..
Normal Ink
!!!
Cover Message
Invisible Ink
Sender Supervised Channel
Receiver
4
Digital Steganography Schemes
• Various message carriers– Digital contents
• Texts, images, audio, video
– Storage devices• Unused space or hidden p
artition
– TCP/IP packets• Unused or reserved bits in
the headee
5
Steganalysis
• Hiding information within electronic media requires alternations of the media properties that may introduce some form of degradation or unusual characteristics
• Forms of attacks and analysis on hidden information– Detecting – Extracting– Disabling/destroying
• The attacking approaches vary depending upon the methods used to embed the information into the cover media– An arms race?
Alice Bob
Eve
6
Biometric Recognition
• Biometrics = “life”+”measure”• Automatic recognition of individuals based on
their physiological and/or behavior characteristics
face fingerprint iris
…
user input
7
Requirements of Biometrics
• A biological measurement qualifies to be a biometric if it satisfies– Universality– Distinctiveness– Permanence – Collectability
• A practical biometric system must satisfy– Performance– Acceptability– Circumvention
8
A Biometric System
9
Applications of Biometrics
• Secure access to– Buildings– Computer systems– Laptops– Cell phones– ATMs
• “who he is” instead if “what he possesses” and “what he remembers”
ID Card
Password
10
Content Tampering
• Image tampering– Object removing– Composition– Morphing– Re-touching– Enhancing– Computer graphics– Painting
11
Watermarking-Based Forensics
• Watermarking-based schemes– Fragile watermarking
• Watermarks will be undetectable when the content is changed in any way
– Semi-fragile watermarking• Watermark will survive only
legitimate distortion
– Watermarks enabling distortion localization or restoration
• A major drawback– Watermarks must be embedded
either at the time of recording or afterwards by a person authorized to do so Example: A Secure Digital Camera
12
Statistical Techniques for Detecting Traces
• Assumption – Digital forgeries, though visually imperceptible,
alter some underlying statistical properties of natural images
• Techniques– Re-sampled images
• Correlations between neighboring pixels
– Color Filter Array (CFA) interpolated images• Correlations are destroyed when the image is tampered
– Double compressions– Duplicated regions– Inconsistent noise patterns
13
References
• Neil F. Johnson and Sushil Jajodia , “Steganalysis: The Investigation of Hidden Information,” IEEE Information Technology Conference, New York, USA, September 1998
• Anil K. Jain, Arun Ross and Salil Prabhakar, “An Introduction to Biometric Recognition”, IEEE Transactions on Circuits and Systems for Video Technology, Special Issue on Image- and Video-Based Biometrics, Vol. 14, No. 1, January 2004
• Paul Blythe and Jessica Fridrich, “Secure Digital Camera,” Digital Forensic Research Workshop, 2004
• Alin C. Popescu, Statistic Tools for Digital Image Forensics, PhD Dissertation, December 2004