International Telecommunication Union MULTIMEDIA WATERMARKING IN ENHANCING DIGITAL

International Telecommunication Union MULTIMEDIA WATERMARKING IN ENHANCING DIGITAL SECURITY Dr. Aloknath De, Director, DSP, HSS ITU-T and ITU-D Workshop Bangalore (India), 30 -31 August 2001 Page -

Motivation for Digital Watermarking 1. Content creator being able to refute others’ claim for creation 2. Creator/owner being able to detect illegal distribution 3. Creator being able to identify illegal alteration and claiming to be genuine * Content creators and legitimate distributors looking for technologybased solutions for combating IPR infringement. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 2

Cryptography, Steganography & Watermarking o Cryptography solves message 15. 09. 2020 integrity issue in secure communication o Digital signatures with private keys enhances it further; solves nonrepudiation problem. o Traditional system does not associate cryptographic information permanently with content …. contd. ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 3

Cryptography, Steganography & Watermarking o For extended guarantee about digital content, additional information needs to embedded o Steganography---Powerful techniques used to hide one message inside another, without disclosing existence of hidden message. . contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 4

Cryptography, Steganography & Watermarking o Steganography conceals “meta- information about a message, such as its existence, duration, sender and receiver” o Watermarking---Fundamental concept of steganography transferred to digital world using modern cryptography concepts and DSPs. . . contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 5

Cryptography, Steganography & Watermarking o Watermark embeds information into digital data in a secret, inconspicuous way < Steganography hides a message within some other content, while digital watermarking focuses on preventing attackers from tampering with the watermark, without necessarily worrying on attackers’ knowledge about it 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 6

Properties of Watermark o Imperceptibility---Watermark not 15. 09. 2020 noticeable (audible/visible); degradation of original content quality minimal o Sufficient Redundancy---Highly redundant watermark can be embedded without being noticeable o Robustness---Robust against common distortions; resistant to manipulations and geometric distortions …. contd. ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 7

Properties of Watermark o Tamper-Resistance---Resistant to signal processing; signal must tolerate small, well-defined modifications without changing its semantics o Representation-Independence--Independent from representation in which media data is stored (otherwise, it could be removed from one form to another) …. contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 8

Properties of Watermark o Domain-Specific---Must be designed specifically for each domain (audio, video and so on) o Adaptability to Attack---Robust algorithm must adapt itself to expected attacks within specified domain o Fragility---Ownership label robust, but integrity label fragile …. contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 9

Properties of Watermark o Key Restrictions---Level of restriction (“restricted key” and “unrestricted key”) placed on ability to read a watermark o It must be reliable enough to withstand careful scrutiny in a court of law and earn public trust/acceptance o Economically implementable in electronic devices and could be validated 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 10

Limitations o Comes into play once offense is made; not a panacea for protecting copyrights on digital content o Provides evidence in front of legal system; method alone not enough protection against would-be attackers o Detecting secret watermarks a computationally complex operation; difficult to use web for thorough search 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 11

Limitations o Relies on properties of data that include a natural noise margin---Real -world data better than artificial data (ray-traced scenes) o Plain text and executable files (which has less redundancy) can be easily attacked---A difficult media 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 12

Watermarking Process o Two major steps involved • Location Selection---Where to embed watermark • Signal Processing---How to modify original data to embed watermark o Two major goals · Watermark Insertion---Cover object and secret key combined to make stego object …. contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 13

Watermarking Process · Watermark Extraction---Stego object and secret key combined to detect watermark o Enhancement of Security--- Encrypting watermark before embedding o Watermarking Types--Robust/fragile, visible/invisible 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 14

Watermarking Schemes o Simple LSB Hiding---All bits in one or more LSB planes of object replaced with watermark o Secret Key-Based Data Hiding--Secret key to choose some pseudorandom bits and replace them with watermark o Spread Spectrum Techniques---Uses entire spectrum of image to embed the watermark resulting in low interception probability …. contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 15

Watermarking Schemes o Perceptual Method---Exploits “perceptual masking” properties of human auditory system where alterations are less noticed < Design of complex, robust schemes that can withstand common contentaltering operations, such as filtering, re-quantization, dithering, scaling etc. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 16

Attacks on Watermarking o Robustness Attack • Uncorrelated Noise Addition • Collusion Attack---“averaging” effect • Inversion Attack o Presentation Attack · Chopping Attack---distributes original image’s watermark …. contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 17

Attacks on Watermarking o Interpretation Attack · Overmark with second watermark o Legal Attack · Attacker uses legal precedent, identity or reputation of content owner < No known watermarking system impervious to every known attack 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 18

Multimedia Applications o ‘Trustworthy Digital Camera’ for o o authenticity and proof-of-ownership Fragile watermark enhancing value of any copy of content Feature tagging to encode descriptive information Embedded captioning with metainformation about content Data hiding in text---Vatican library …. contd. 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 19

Multimedia Applications 1. Content-based watermarking for MP 3 compressed audio 2. Video stream acquired, processed and broadcast in TV production chain ---Frame-based watermark monitoring process 3. Reversible Visible Watermarking--Watermarked image as “teaser” 4. Worm (e. g. , Marc. Spider) searching internet for illegal copies 15. 09. 2020 ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 20

Concluding Remarks o Digital WM complementing o o o 15. 09. 2020 Steganography and Encryption Protection of proprietary digital content Technological challenges in content protection Legal issues in content distribution and authenticity Numerous watermark products in market Standardization effort in ITU and other bodies ITU-T and ITU-D Workshop - Bangalore (India), 30 -31 August 2001 21