Introduction to Multimedia Security Topics Covered in this Course. Multimedia Security

Transcription

1 Introduction to Multimedia Security Topics Covered in this Course Multimedia Security

2 Course Coverage Multimedia Security Digital Rights Management Steganography/ Steganalysis DRM Standards Rights Languages Digital Forensics DRM Laws Digital Watermarking Multimedia Cryptography Biometrics Privacy-Preserving Data Mining 2

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..o xx.. Sender Cover Message Genuine Message!!! Supervised Channel..o xx.. Cover Message Receiver..o xx..!!! Genuine Message + Cover Message Paper Normal Ink Invisible Ink Paper with Messages Examination Heating Examination 3

4 Digital Steganography Schemes Various message carriers Digital contents Texts, images, audio, video Storage devices Unused space or hidden partition TCP/IP packets Unused or reserved bits in the header 4

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 Alice Eve The attacking approaches vary depending upon the methods used to embed the information into the cover media An arms race? Bob 5

6 Biometric Recognition Biometrics = life + measure Automatic recognition of individuals based on their physiological and/or behavior characteristics face fingerprint iris user input 6

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 7

8 A Biometric System 8

9 Applications of Biometrics Secure access to Buildings Computer systems Laptops Cell phones ATMs ID Card Password who he is instead of what he possesses and what he remembers 9

10 Content Tampering Image tampering Object removing Composition Morphing Re-touching Enhancing Computer graphics Painting 10

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 11

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 12

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