Attacks on Digital Image Watermarks: An Experimental Study€¦ · Digital Image Watermarking •...
Transcript of Attacks on Digital Image Watermarks: An Experimental Study€¦ · Digital Image Watermarking •...
Attacks on Digital Image Watermarks: An Experimental Study
Authors: Yuru Liu, Xuan Wu, Xiaohan Tang | Institute for Software Research | Carnegie Mellon University
Digital Image Watermarking• Digital watermarking is the embedding of signal, secret
information into the digital carrier such as image, audio and video.
• Digital image watermarking is mainly used in data authentication, copyright protection, and owner identification, etc.
• There are three categories of Algorithms: spatial domain, spectral domain, and hybrid domain
Experimental Result
Experimental Design
• 25 original image files• 5 subject topics: scenery, portrait, objects/design,
plain text, poster• 4 formats: JPG, BMP, PNG, TIF• 100 test images in total
TestImages
• Least Significant bit (LSB)• Discrete Fourier Transformation Based (DFT)• Discrete Wavelet Transformation Based (DWT)
TargetWatermarkingAlgorithms
• 13 attack methods including typical geometric transformations, compression, adding noise and filtering.
• Parameters (intensity) of each method are tuned to satisfy the constraint that PSNR of all attacked images are above a threshold value (20 db)
AttackMethods
• For each (algorithm, attack method) pair, we inspect all the attacked watermarks with naked eye, and record the ratio of unrecognizable watermarks for comparison
Evaluation
Conclusion and Limitations
• Watermarked Images under different themes could havedivergent levels of resistance towards different attack methods.Usually a watermarked image that has high resistance towardsone type of typical attack methods presents high vulnerability toanother. With limited knowledge of watermarking algorithms thathave been applied to the images, employing a single attackmethod can therefore be quite useless. Thus, combiningmultiple attack methods together should be the first choice whentrying to remove an embedded watermark.
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Unrecognizable Watermark Ratio for LSB Algorithm
Average filtering
Brightness
Compression
Cropping
Gaussian Noise
Hue
Median Filtering
Pepper & Salt Noise
Poisson Noise
Rotation
Saturation
Speckle Noise
Translation
Attacks on Watermarks• No watermarking algorithm is completely robust.
Vulnerabilities vary from algorithm to algorithm.• Malicious attacks can lead to partial or even total
destruction of the embedded watermarks • Attacks can be classified as active attacks, passive
attacks, collusion attacks, and forgery attacks
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Unrecognizable Watermark Ratio for DFT Algorithm
Average filtering
Brightness
Compression
Cropping
Gaussian Noise
Hue
Median Filtering
Pepper & Salt Noise
Poisson Noise
Rotation
Saturation
Speckle Noise
Translation 0.12 0.78 0.1 0.54 0.26 0.8 0.39 0.34 0.37 0.45 0.88 0.41 0.890.0
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Unrecognizable Watermark Ratio for DWT Algorithm
Average filtering
Brightness
Compression
Cropping
Gaussian Noise
Hue
Median Filtering
Pepper & Salt Noise
Poisson Noise
Rotation
Saturation
Speckle Noise
Translation
Our goal• In this project, we conduct active attacks on image
watermarks from an adversary’s perspective. Given an watermarked image with no other information, we try to remove the watermark.
• Through a standardized experiment, we evaluate the effectiveness of various attack methods applied at different watermarking algorithms
Figure2.Flowchartofourexperiment
Figure1.DigitalWatermarkingSystem