Multimedia Multimedia SecuritySecurity

Part I: Digital Part I: Digital WatermarkingWatermarking

Subrata AcharyaSubrata Acharya

CS 2310, Spring 2007CS 2310, Spring 2007

Digital Watermarking?Digital Watermarking? Allows users to embed some data into Allows users to embed some data into

digital contentsdigital contents

When data is embedded, it is not written When data is embedded, it is not written at header part but embedded directly into at header part but embedded directly into digital media itself by changing media digital media itself by changing media contents datacontents data

How It WorksHow It Works

Data HidingData Hiding

Types of WatermarkTypes of Watermark VisibleVisible

A visible A visible translucent image translucent image which is overlaid which is overlaid on the primary on the primary image image

InvisibleInvisible An overlaid image An overlaid image

which cannot be which cannot be seen, but which seen, but which can be detected can be detected algorithmically algorithmically

Visible WatermarkVisible Watermark Logo or seal of the organization which Logo or seal of the organization which

holds the rights to the primary image, it holds the rights to the primary image, it allows the primary image to be viewed, allows the primary image to be viewed, but still marks it clearly as the property of but still marks it clearly as the property of the owning organization.the owning organization.

Overlay the watermark in a way which Overlay the watermark in a way which makes it difficult to remove, if the goal of makes it difficult to remove, if the goal of indicating property rights is to be indicating property rights is to be achieved. achieved.

Visible WatermarkVisible Watermark

Invisible WatermarkInvisible Watermark

Embedding level is too small to noticeEmbedding level is too small to notice Can be retrieved by extraction Can be retrieved by extraction

softwaresoftware Applications:Applications:

AuthenticationAuthentication CopyrightingCopyrighting Etc…Etc…

Invisible WatermarkInvisible Watermark

Embedding TechniquesEmbedding Techniques

Spatial domainSpatial domain Original neededOriginal needed Original not neededOriginal not needed

Frequency domainFrequency domain Original neededOriginal needed Original not neededOriginal not needed

Spread domainSpread domain

Spatial DomainSpatial Domain

Frequency DomainFrequency Domain

Watermarking signal to embedWatermarking signal to embed

Host signalHost signal

Frequency componentsFrequency components

EmbeddingEmbedding

ExtractionExtraction

NvvvV ,...,, 10

NxxxX ,...,, 10

NfffF ,...,, 10

iii xff

iii ffx

Frequency DomainFrequency Domain

Spread SpectrumSpread Spectrum

Spread SpectrumSpread Spectrum

Applications of Applications of WatermarkingWatermarking

Rights managementRights management

Contents managementContents management

Access/copy controlAccess/copy control

AuthenticationAuthentication

Features of Features of WatermarkingWatermarking

Invisible/InaudibleInvisible/Inaudible Information is embedded without digital content Information is embedded without digital content

degradation, because of the level of embedding degradation, because of the level of embedding operation is too small for human to notice the change. operation is too small for human to notice the change.

InseparableInseparable The embedded information can survive after some The embedded information can survive after some

processing, compression and format transformation.processing, compression and format transformation. Unchanging data file sizeUnchanging data file size

Data size of the media is not changed before and after Data size of the media is not changed before and after embedding operation because information is embedded embedding operation because information is embedded directly into the media.directly into the media.

Technical Requirements for Technical Requirements for WatermarkingWatermarking

Invisibility

CapacityRobustness

Digital Watermarking Digital Watermarking AllianceAlliance

Represents applications and solutions for:Represents applications and solutions for:

Audio and Music ContentAudio and Music Content

Video, Movies and TV ContentVideo, Movies and TV Content

Digital ImageryDigital Imagery

Identity DocumentsIdentity Documents

Value DocumentsValue Documents

Digital Watermarking Digital Watermarking Alliance MembersAlliance Members

Digital Watermarking Digital Watermarking ExamplesExamples

Copyright CommunicationCopyright Communication Copy ProtectionCopy Protection MonitoringMonitoring Filtering/ClassificationFiltering/Classification Authentication/IntegrityAuthentication/Integrity

Product Serialization & TrackingProduct Serialization & Tracking Asset/Content ManagementAsset/Content Management Rights ManagementRights Management Remote TriggeringRemote Triggering Linking/E-CommerceLinking/E-Commerce

Potential Usage Models Potential Usage Models and Benefitsand Benefits

User Software Usage Models

Detect Copyright DWM

Detect Content ID

Copyright CommunicationP2P systems only distribute non-copyright content

Licensed ContentP2P systems can resell copyrighted content with license agreements with content owners

Enhanced ContentP2P systems provide or sell media content information and related items

Copyright Digital Copyright Digital Watermark ArchitectureWatermark Architecture

Audio/Video MasterEmbed Copyrightand Content ID DWM

Content Owner

Provider Index Database Location(Centralized or Distributed)

User’s PC

Rip SoftwareCompressed Audio/VideoFile (e.g. MP3 file)

User SoftwareDetect Copyright and Content ID DWM for Secure and Enhanced content

Rights & Info Database

Content ID linked to rights,

information and related content

Can be used to address P2P and social network content Identification needs as

well as providing identification of orphan works and access to

metadata/networked information

Filtering & ClassificationFiltering & Classification

Can support existing, established and/or new Classification Systems or content Can support existing, established and/or new Classification Systems or content identifiers such as MPAA film ratings, ISAN or ad identification codes, etc.identifiers such as MPAA film ratings, ISAN or ad identification codes, etc.

Filtering can occur at the whole content level and/or at a more granular level identifying Filtering can occur at the whole content level and/or at a more granular level identifying copyrighted, sensitive and/or questionable material for the given audiencecopyrighted, sensitive and/or questionable material for the given audience

May be key element of identifying copyrighted content to support legitimate P2P May be key element of identifying copyrighted content to support legitimate P2P distributiondistribution

Copyrighted

Non-Copyrighted

Content Filter

Access Legitimate Copy or License

Connected Connected Content/LinkingContent/Linking

Captured CD e-logo links to web and music downloads

DOWNLOAD Ring tones Buy tickets Reviews Tour dates Samples Band info

Promoting & Facilitating M-CommercePromoting & Facilitating M-Commerce

Location based servicesLocation based services

Multimedia accessMultimedia access

Streaming audioStreaming audio MusicMusic MultimediaMultimedia BookmarkingBookmarking

Digital Media Serialization Digital Media Serialization & Tracking& Tracking

Protected for privacy

Identifies content owners and rights while communicating copyright Identifies content owners and rights while communicating copyright informationinformation

Awareness of watermarked content by consumer creates deterrent against Awareness of watermarked content by consumer creates deterrent against unauthorized copying and distributionunauthorized copying and distribution

Provides accurate identification of source of unauthorized content Provides accurate identification of source of unauthorized content discovered on the Internet and/or physical mediadiscovered on the Internet and/or physical media

(1) At Point of Distribution

(2) At point of copying/re-distribution

Recordable Media

EmbedSerial # (2)

EmbedSerial # (1)

Content ID

Retail Content

Content Provider

Track and take proper action Detect

Serial Number

Multimedia Multimedia SecuritySecurity

Part II: EncryptionPart II: Encryption

Subrata AcharyaSubrata Acharya

CS 2310, Spring 2007CS 2310, Spring 2007

GoalsGoals Person authenticationPerson authentication

Assurance that the communicating entity is the one Assurance that the communicating entity is the one claimedclaimed

Access controlAccess control Prevention of unauthorized use of a resourcePrevention of unauthorized use of a resource

Data confidentialityData confidentiality Protection of data from unauthorized disclosureProtection of data from unauthorized disclosure

Data integrityData integrity Assurance that data received is as sentAssurance that data received is as sent

Non-repudiationNon-repudiation Protection against denial by the parties in a Protection against denial by the parties in a

communicationcommunication

Multimedia DataMultimedia Data

What separates multimedia data from What separates multimedia data from traditional alpha numeric data?traditional alpha numeric data? LargeLarge in file size in file size

May require May require real-timereal-time processing processing (especially for continuous media)(especially for continuous media)

Portable and Portable and mobilemobile applications applications

Multimedia Encryption Multimedia Encryption ApproachApproach

Signal scramblingSignal scrambling Historical approachHistorical approach Not compatible with modern multimedia compressionNot compatible with modern multimedia compression Fast speed but low securityFast speed but low security

Total encryption with cryptographic ciphersTotal encryption with cryptographic ciphers Trivial solutionTrivial solution High security but slow speedHigh security but slow speed

Selective encryptionSelective encryption Most popular approach todayMost popular approach today Limited in its range of applicationLimited in its range of application

Integrating encryption into entropy codingIntegrating encryption into entropy coding Complementary to selective encryptionComplementary to selective encryption Very fast computation speedVery fast computation speed

Selective EncryptionSelective Encryption Select the most important coefficients and then encrypt Select the most important coefficients and then encrypt

them with traditional ciphers such as DESthem with traditional ciphers such as DES

AdvantagesAdvantages Lower complexityLower complexity High security level provided by traditional cryptologyHigh security level provided by traditional cryptology Less error correction coding redundancyLess error correction coding redundancy Compatible with existing software and hardware modulesCompatible with existing software and hardware modules

MediaCompressi

onSystem

Coefficient

Selection

Cryptographic

Cipher

ErrorCorrection

Coding

DigitizedAudiovisu

aldata

Coefficients

SelectedCoefficient

s

Non-selected

Coefficients

Transmission channel or storage media

Example: Selective Example: Selective Encryption for G.723.1 Encryption for G.723.1

Speech CoderSpeech Coder ITU-T Recommendation G.723.1ITU-T Recommendation G.723.1

A popular low bit rate speech codecA popular low bit rate speech codec Based on the human voice generation modelBased on the human voice generation model

VocoderVocoder Decoder synthesizes speech using the modelDecoder synthesizes speech using the model

LSPDecode

r

PitchDecode

r

ExcitationDecoder

+ Synthesis

Filter

PitchPostfilte

r

LSPInterpolato

r

FormantPostfilter

Gain Scaling

Unit

LSP codebook indices

Lag of pitch predictorsGain vectors

Fixed codebook gainsand others

Vocal Cord

Excitation signal generation

Vocal Tract Linear filter

Randomized Huffman Randomized Huffman Table EncryptionTable Encryption

0

0

0 0

11

1

1 1

A

0 1

B CD E F G

0

1

0 1

10

1

1 0

A

0 1

B CD E F G

0 0

BADCAEFG

Huffman code #0

Huffman code #1

0000000

0

10011010

100011001010110111101111

110011001110110110111111

isomorphic tree!

Multimedia Encryption Multimedia Encryption with Randomized with Randomized

Entropy CoderEntropy Coder Select a good PRBGSelect a good PRBG Select Select an an rr-bit random seed -bit random seed s s (encryption key)(encryption key) Pseudo-random sequence output from PRBG(s) Pseudo-random sequence output from PRBG(s)

becomes the key hoping sequence (KHS)becomes the key hoping sequence (KHS)

Entropy

Coder

PRBGs KHS = 011000110 …

Input symbol

1110110001…

101

1110

ChallengesChallenges

Real timeReal time constraint constraint

Potential Potential costcost constraint constraint

Potential Potential bit ratebit rate increase increase

Rate variationRate variation challenge challenge

Dynamic networkDynamic network conditions conditions

TranscodingTranscoding challenge challenge

ConclusionConclusion

Multimedia security relevanceMultimedia security relevance

Tradeoff approach based on applicationTradeoff approach based on application

Goal is the design of an Goal is the design of an efficientefficient, , securesecure and and cost effectivecost effective technique for multimedia technique for multimedia

security using security using digital watermarkingdigital watermarking and and encryptionencryption

Thank you !!!Thank you !!!