Information System SecurityAABFS-JordanSummer 2006

Watermarking

Presented To: Dr. Lo'ai Tawalbeh Prepared By: Sami Qawasmeh

OutlineInformation Hiding overviewIntroduction: History , Definition, and MotivationWatermarking Classification : Paper and Digital WMDesired Properties of WatermarkDigital Watermarking TypesWatermarking Process Embedding and Extraction.Watermarking TechniquesWatermarking Attackers and AttacksLimitations and ConclusionsFuture Researches References

What is Information Hiding?Classical: Embedding information so that it cannot be visually perceivedModern : Embedding information in digital data so that it cannot be visually or audibly perceived

Why Hide Information?There are two major issues

Because you want to protect it from malicious useprotect intellectual property rights(IPR)

Because you do not want any one to even know about its existenceAvoid observation by unintended recipients Security through obscurity

Information Hiding Main DisciplinesSteganography- (covered writing) the process of secretly embedding information into a data source in such a way its very existence is concealed. Watermarking:

DefinitionsWatermark : is a secret message that is embedded into a cover message.

Digital watermark: is a visible or perfectly invisible, identification code that is permanently embedded in the data and remains present within the data after any decryption process.

HistoryThe Italians where the 1st to use watermarks in the manufacture of paper in the 1270's.

A watermark was used in banknote production by the Bank of England in 1697.

It is a good security feature because the watermark cannot be photocopied or scanned effectively.

Why Watermark? Motivation (1/2)The rapid revolution in digital multimedia and the ease of generating identical and unauthorized digital data. For example: USA Today, Jan. 2000: Estimated lost revenue from digital audio piracy $8,5 billions

Digital objects can be copied and distributed, transmitted, manipulated anonymously with no way to identify the criminals.

Copyright protection of multimedia data Copyright owners want to be compensated every time their work is used.

Why Watermark? Motivation (2/2)The need to limit the number of copies created whereas the watermarks are modified by the hardware and at some point would not create any more copies (i.e. DVD) - the reading device must be able to modify the watermark

Content protection content stamped with a visible watermark that is very difficult to remove so that it can be publicly and freely distributed

Watermarks Classification Paper Watermark: Intended to be somewhat visible.

Digital Watermark: A digital signal or pattern imposed on a digital document ( text, graphics, multimedia presentations ,

Paper Watermark The technique of impressing into the paper a form, image, or text.

Cannot be photocopied or scanned effectively

Purpose: To make forgery more difficult to record the manufacturers trademark, Copyright protection, logos, ect

Used in : Currency, Banknotes , Passports,

Paper watermarkExample

Some Digital Watermarking Types (1/2)Visible vs. Invisible:Visible such as a company logo stamped on an image or Video.Invisible intended to be imperceptible to the human eye or inaudible. the watermark can only be determined through watermark extraction or detection by computers.

Fragile vs. Robust :Fragile watermarks break down easily.Robust survive manipulations of content.

Some Digital Watermarking Types (2/2) Public vs. private Private watermarking techniques require that the original be used as a basis of encryption whereas public does not Public-key vs. secret-key Secret-key watermarking uses the same watermarking key to read the content as the key that was inserted into the image; public key uses different keys for watermarking the image and reading the image

Some Desired Properties of (DW) ( 1/3) RobustnessTamper Resistance Economically ImplementableUnambiguous CapacityQuality

Desired Properties ( 2/3)(1) Robustness: A watermark must be difficult or impossible to remove, at least without visibly degrading the original image. A watermark must survive image modifications. Geometric distortions: rotation, scaling, translation, etc.

(2) Tamper Resistance: The watermark must resist any type of attacks, what ever the intentions are: remove or modify

Desired Properties ( 3/3)(3) Economically implementable: Time and effort, cost.(4) Unambiguous: The watermark, when retrieved, should unambiguously identify the owner.(5) Capacity: The amount of information that can be embedded(6) Quality: (High Quality) - Quality not degraded

Properties TradeoffRobustnessCapacityQualityEmbedding and Extraction Complexity

Important DefinitionsCover : Audio-video, text in which data will be hiddenWatermark: What is actually added to the coverInformation: message to be added Watermarking key: Secret parameter needed for embedding & detecting the watermark & extracting the informationWatermarking Function: Embedding & Extraction algorithms.

Watermarking ProcessTwo major steps:

Location Selection : Where to embed watermark Processing : How to modify original data to embed watermark

Watermarking Embedding & Extraction Cover ImageCover + WMEmbedding F : Watermarked Image = Function (Cover, Watermark, Key)Extraction F : Watermark = Function (Watermarked Image, Key( Cover + WM

Watermarking TechniquesText Varying spaces after punctuation, spaces in between lines of text, spaces at the end of sentences, etc. Audio Low bit coding, random.

Images / Video Least-significant bit, random

Text Watermarking Techniques: Varying spaces after punctuation, spaces in between lines of text, spaces at the end of sentences, etc.Examples:Line Shift Coding : Shift every other line up or down slightly in order to encode data Word Shift Coding: Shifts some words slightly left or right in order to encode data

Image Watermarking / LSBLSB: Using the least significant bits of each pixel in one image to hide the most significant bits of another.Pixels may be chosen randomly according to a key Steps: Load up both the host image and the image you need to hide. Chose the number of bits you wish to hide the secret image in. Combine the pixels from both images

LSB - Example0 0 1 1 1 1 0 00 1 0 0 0 0 1 01 0 1 1 1 1 0 11 0 1 0 0 0 0 11 0 1 0 0 0 0 11 0 1 1 1 1 0 10 1 0 0 0 0 1 00 0 1 1 1 1 0 0

Audio WatermarkingLow Bit CodingEcho Data Hiding

Audio WatermarkingLow Bit CodingMost digital audio is created by sampling the signal and quantizing the sample with a 16-bit quantizer. The rightmost bit, or low order bit, of each sample can be changed from 0 to 1 or 1 to 0 This modification from one sample value to another is not perceptible by most people and the audio signal still sounds the same

Audio WatermarkingEcho Data HidingDiscrete copies of the original signal are mixed in with the original signal creating echoes of each sound. By using two different time values between an echo and the original sound, a binary 1 or binary 0 can be encoded.

Video WatermarkingVideo sequences consists of a series of consecutive and equally time-spaced (Frames) still images in general, very similar with image watermarking so, image watermark method is applicable to video directly

Video watermark imposes real or near real-time watermarking system

Attackers Main Goal Attackers seek to destroy watermark for the purposes of use without having to pay royalties to the originator of the content.

Why do we need to study attacks? Identify weakness Propose improvement Security Attackers are knowledgeable, creative, have lots of time, and are numerous

Attacks on Watermarking Two Sets of AttacksUnintentional All image manipulations commonly used to prepare images for print publication. For example:Resizing, rotation, sharpening, contrast modification, compression, ect.Intentional (Malicious)All the well-known intentional attacks include: Disabling, altering, embedding new watermark, ect.

Intentional Watermark Attacks (1/2)Active Attacks hacker tries to remove the watermark or make it undetectable. Applying Geometric transformation: rotation, scaling, translation, change aspect ratio.

Passive Attacks hacker tries to determine whether there is a watermark and identify it. However, no damage or removal is done.

Collusion Attacks hacker uses several copies of one piece of media, each with a different watermark, to construct a copy with no watermark.

Intentional Watermark Attacks (2/2)Forgery Attacks Attacher tries to embed a valid watermark of their own rather than remove one.Conspiracy Attacks : several conspirators, each of whom has procured a copy of the same image (differing only in the watermark which is unique to each copy). Presentation Attacks: Watermark detection failure. Geometric transformation, rotation, scaling, translation, change aspect ratio, etc.

Limitations / ConclusionsRapidly growing field of digitized images, video and audio has urged for the need of protection.Watermarking is a key process in the protection of copyright ownership of electronic data (image, videos, audio, ...). Digital watermarking does not prevent copying or distribution.Digital watermarking alone is not a complete solution for access/copy control or copyright protection.Digital watermarks cannot survive every possible attack.

Challenges in Watermarking ResearchWatermark survival for all types of attacks intentional and unintentional.Embedding a Color image watermarkingMultiple layers watermark that aim to protect each other from being analyzed -The more robust and reliable the implementation is, the longer it will last.

ReferencesM. Kutter, S. Voloshynovskiy and A. Herrigel, The watermark Copy Attack, Security and Watermarking of Multimedia Contents, II, SPIE-3971: 371-280, 2000.S. Craver, N. Memon, B.-L. Yeo, and M. Yeung. Resolving rightful ownerships with invisible watermarking techniques: Limitations, attacks and implications. IEEE Trans. on Selected Areas of Communications, 16(4):573586, 1998.I. Cox, J. Kilian, F. T. Leighton, and T. Shamoon. Secure spread spectrum watermarking for multimedia. IEEE Trans. on Image Processing, 6(12):16731687, 1997.I. J. Cox and J.-P. Linnartz. Some general methods for tampering with watermarks. IEEE Trans. on Selected Areas of Communications, 16(4):587593, 1998.

Referenceshttp://www-nt.e-technik.uni-erlangen.de/~su/seminar /ws99/slides/su.pdfhttp://www.compris.com/TextHide http://www.infosyssec.com/infosyssec/Steganography/watermarkingAttack.htmhttp://www.lnt.de/~hartung/ProcIEEEHartungKutter.pdfhttp://www.watermarkingworld.org http://wwwstu.hatii.arts.gla.ac.uk/Courses/digitisationhttp://www.inria.fr/Watermarkinghttp://www.isg.rhul.ac.uk/msc/teaching/opt5/archive/2002-03/slides/watermarking.pdf

Thanks for your kind attention

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