ch 7 multimedia security arini, st, mt arinizul@gmail. com [email protected]
TRANSCRIPT
Ch 7Multimedia Security
Arini, ST, MTarinizul@gmail. [email protected]
Contents
MotivationGoalsWays
Authentication : Data Hiding (watermarking & Steganography), Digital Fingerprint /signature
Confidentiality : Encryption
Integrity : hash (Digital Fingerprint /signature)
Access Control :
Non repudiation : third partyDigital Rights Management (DRM).
I. MotivationThe recent growth of networked multimedia
systems has increased the need for the protection of digital media
Digital media • Audio
• Video
• Documents (including HTML documents) : email
• Images
• Graphic or Scene Models
• Programs (executable code)
I. MotivationElectronic/digital media Record conditions :
1. Very easy to make copies : ???
2. Very fast distribution
3. Easy archiving and retrieval
4. Copies are as good as original : ???
5. Easily modifiable : ???
6. Environmental Friendly
I. MotivationWithout such methods, placing images, audio
or video sequences on a public network puts them at risk of theft and alteration.
Techniques are needed to prevent the copying, forgery and unauthorized distribution of multimedia elementsThis is particularly important for the protection
and enforcement of intellectual property rights. • Copyright protection involves the authentication
of media ownership, and the identification of illegal copies of the (possibly media.
II. Goals Goals of Multimedia streams (Multimedia Security)
Secure communications
Secure delivery : • Copyright protection (originality)• Prevent forgery, illegal copying, illegal distribution
(Integrity)• Tamper proofing, • Access control • visual encryption
Secure Internet/Network :
III. Ways (Approaches)Cryptography Techniques :
Multimedia Authentication• Multimedia Signature & Watermark
Multimedia Confidentiality (Encryption)
Multimedia Identifications and Access Control
Multimedia Integrity
Multimedia Non-repudiationsImplemented into : Digital Right Management
Watermarking, steganography, digital signature, fingerprint
3.1. Cryptography Techniques 1. Authentication: providing assurance of the identity of the
multimedia data sender (assure the credibility of multimedia content) Primary tool: Digital signatures (data hiding : watermarking, steganography)
2. Confidentiality: protecting multimedia data from unauthorized disclosure (Secure content transmission privacy) Primary tool: Encryption (DES, AES, RSA, Diffie Hellman, ….., )
3. Integrity: providing assurance that multimedia data has not been altered in an unauthorized way (Assurance that data received is as sent) Primary tool: Hashing
4. Access Control Prevention of unauthorized use of a resource (Protect multimedia data from
illegal distribution and theft)
5. Non-repudiation: preventing a party from denying a previous action. (Protection against denial by the parties in a communication) Primary tool: Trusted third party service
3.1.1. Authentication
Authentication techniques : Passive Authentication
• Three Image tampering (Enhancing, Compositing, Copy/Move)
Active Authentication• Data Hiding :
– Watermarking (Embedding techniques, Application, Types (Visible&Invisible), Alliance Member
– Steganography
• Digital Signature/Digital Fingerprint
3.1.1.1. Passive AuthenticationNo requirement of knowledge of
original image.Does not rely of presence of watermark
or fingerprint.Identify media tampering methods.
Example : Three image tampering (enhancing, compositing & copy/move)
a. Three Image TamperingThere are three main categories of image
tampering:Enhancing
Compositing
Copy/Move
1. Enhancing
Changing the color of objects
Changing the weather conditions
Blurring out objects
2. Compositing
Combining two or Combining two or more images to create more images to create
a new imagea new image
Compositing / Re-sampling Detection
Original Image Tampered Image
Periodic pattern in FourierTransform of altered region
Fourier Transform of unaltered region
3. Copy-Move
Copying regions of the original image and pasting into other areas.
The yellow area has been copied and moved to conceal the truck.
Copy-Move Detection
Original Image Tampered Image
Original Image Tampered Image PCA Detection
3.1.1.2. Active AuthenticationAssess methods available for protecting media.Require knowledge original imageRely on :
Data Hiding : • Watermarking/Digital watermarking • Steganography
Digital Fingerprint/signature
Algorithm/key used to embed the watermark or fingerprint.
3.1.1.2. Active Authentication
3.1.1.2.1. Data Hiding Watermarking
Steganography
3.1.1.2.2. Digital Signature/Fingerprint
Extractionfunction
M(L)
Channel
Retrieved information
M(L)
Key
Original data
Information to embed
Embeddingfunction
^
3.1.1.2.1. Data Hiding
A. Watermarking/Digital Watermarking
Watermarking is a concept of embedding a special pattern into the Audio, video, image and text a given piece of information, such as the owner’s or
authorized consumer’s identity, is indissolubly tied to the data.
This information can later : • prove ownership,
• Identify a misappropriating person,
• Trace the marked document’s dissemination through the network,
• Or simply inform users about the rights-holder or the permitted use of the data
Allows users to embed some data into digital contents
When data is embedded, It is not written at header part but
embedded directly into digital media itself by changing media contents data
A. Watermarking/Digital Watermarking
OriginalInformation
WatermarkedInformation
a. Embedding TechniquesSpatial domain
Watermark embedded by directly modifying the pixel values.
Usually use spread spectrum approach. Original needed (Non Blind) Original not needed (Blind)
Frequency domain Original needed (Non Blind) Original not needed (Blind) Usually use Transform domain watermarking-
Watermark embedded in the transform domain e.g., DCT, DFT, wavelet by modifying the coefficients of global or block transform.
Spatial Domain
Spatial watermarking example
Original image Watermarked image
Spread Spectrum
Spread Spectrum
Frequency Domain
Watermarking signal to embed
Host signal
Frequency components
Embedding
Extraction
NvvvV ,...,, 10
NxxxX ,...,, 10
NfffF ,...,, 10
iii xff
iii ffx
Frequency Domain
DCT phase modulation (embed m bits)
Embedding algorithmRandomly select a group of low frequency
DCT coefficients using a key.
Generate a binary message as a watermark.
Set the phase of the selected coefficients in accordance with the embedded watermark.
Decoding algorithmUse the same key to select the coefficient.
Extract the sign of the selected coefficients and decode according to the embedding rule.
b. Application of WatermarkingRights management : copyright
Owner Identification
Proof of Ownership
Transaction Tracking and serialization productLinking, E-Commerce
Contents management Copy Control Access/copy control
Authentication&Integrity Content Authentication
MonitoringFiltering & Classification
b1. Copyright
Audio/Video MasterEmbed Copyright
and Content ID DWM
Content Owner
Provider Index Database Location
(Centralized or Distributed)
User’s PC
Rip SoftwareCompressed Audio/Video
File (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
b2. Serialization & Tracking Identifies content owners and rights while communicating copyright
information Awareness of watermarked content by consumer creates deterrent against
unauthorized copying and distribution Provides accurate identification of source of unauthorized content
discovered on the Internet and/or physical media
Protected for privacy
(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
DetectSerial
Number
b2. Connected Content/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-Commerce
Location based services
Multimedia access
Streaming audio Music Multimedia Bookmarking
b3. Filtering & Classification
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 audience
May be key element of identifying copyrighted content to support legitimate P2P distribution
Copyrighted
Non-CopyrightedContent Filter
Access Legitimate
Copy or License
c. Types of WatermarkVisible
A visible information which is overlaid on the primary media
Invisible The information which cannot be seen, but
which can be detected algorithmically
c1. Visible Watermark
Logo or seal of the organization which holds the rights to the primary media It allows the primary information to be
viewed,
But still marks it clearly as the property of the owning organization.
Overlay the watermark in a way which makes it difficult to remove, if the goal of indicating property rights is to be achieved.
Visible Watermark
c2. Invisible WatermarkEmbedding level is too small to noticeCan be retrieved by extraction softwareApplications: Authentication, Copyrighting
c2.1. Fragile WatermarksDesigned to detect every possible change in
pixel values .Variety of Techniques
Most cases, the watermark is embedded in the least significant bit (LSB) of the image.
Advantages: Pick up all image manipulations – malicious and
non-maliciousDisadvantages: Too sensitive
Break very easily under any modification of the host signal
Used for tamper detection or as a digital signature.
c2.2. Semi-Fragile WatermarksThey are robust, to a certain extent, and
are less sensitive to pixel modifications. Techniques:
Divide image into blocks and utilize bits from each block to calculate a spread spectrum noise like signal which is combined with DCT coefficients and inserted as a watermark.
• Review slide number : 27-28 Advantage: less sensitive than fragile
watermarks Used for data authentication. Disadvantage : brake very easily to other
attacks.
Example : Video
Raw video watermarkingDFT
DCTDWT : DWT-based Video Watermarking
Scheme with Scramble Watermark
Watermarking I-frame (Mpeg-1,2)Video object watermarking (Mpeg-4)
Example : Digital Cameras
Watermarking based on secret key, block ID and content. The image is divided into blocks and each
block watermarked using a frequency based spread spectrum technique incorporating the secret key, block ID and block content.
Image of photographers iris is combined with the camera ID, the hash of the original image and other details specific to the camera.
The previous techniques will only detect and localize areas of interest when authentication is carried out.
The watermark should be permanently intact to the host signal
Used for copyright protection. Advantage: Potential for original data to be
retrieved.Disadvantage: Removing the watermark result in destroying the
perceptual quality of the signal (lost information
c2.3. Robust /Self Embedding
d. Digital Watermarking Alliance
e. Limitations of digital watermarking
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.
f. Watermark attacksRobustness attacks:
Intended to remove the watermark. JPEG compression, filtering, cropping, histogram equalization additive noise etc.
Presentation Attacks: Rotation, scaling, translation, change aspect ratio,
line/frame dropping, affine transformation etc. Counterfeiting attacks:
Render the original image useless, generate fake original, dead lock problem.
Court of law attacks: Take advantage of legal issues.
Steganography is the science of hiding information in such a way that no one suspects the information exists both perceptually and statistically (the only the recipient knows of its existence)
Steganography is usually combined with cryptography. With cryptography the information is known to exist,
but it is encoded in such a way that only the intended recipient can read it.
The word Steganography is of Greek origin and means “covered, or hidden writing.”
Steganographic messages will generally appear as something else such as a picture or a text file.
Provide security
B. Steganography
What to hideTexts
Images
SoundHow to hide
embed text in text/images/sound files
embed image in text/image/sound files
embed sound in text/image/sound files
a. History of SteganographyDates back to 440 BC
Heredotus and wax tablets
Histiaeus and his tattooed slave
Later in the 1500’s Johannes Trithemius Steganographia
World War II Micro Dots
Doll Woman
Pueblo Incident in 1968 Sign Language Photos
b.How does it work now?
DataEncrypt
Encrypted Data
CarrierMedia
Steganogram
Application
Hiding in text, images, audio, videoHiding data in unused/reserved disk spaceHiding data in software and circuitryHiding in network packets in TCP headers
for example by utilizing the reserved bits
C. Example : LSBHidden messages can also be implemented
into audio files using the LSB method.Sounds and noises at the LSB level can not
typically be heard by the human ear.
Therefore when playing the original file it sounds just like a normal .wav or .mp3 file
However it can be decrypted to reveal another sound file or any file for that matter.
The File must be big enough to hold hidden message (avoid the information existence)
1. Image LSB
Least significant bit (LSB) encoding Replace the LSB of each pixel with the secret
message
Pixels may be chosen randomly according to a key
Comments: The simplest and most common
steganographic tech.
Premise = change to the least significant bit will be masked by noise commonly present in images.
The one’s bit of a byte is used to encode the hidden information.
Suppose we want to encode the letter A (ASCII 65 or binary 01000001) in the following 8 bytes of a carrier file.01011101 11010000 00011100 1010110011100111 10000111 01101011 11100011becomes01011100 11010001 00011100 1010110011100110 10000110 01101010 11100011
Typical .wav file uses 16 bit sampling.
2. Text LSB
Variations of LSBUse password as a seed for pseudo
random number generator.
Use only those bytes separated by the value of the next random number to hide data.
Advantages - More difficult to detect and decode.
Disadvantage – Limits the number of bytes that are available for holding the payload.
Cryptography usually used in conjunction with steganography Provides an extra layer of security.
Makes the existence of a hidden message more difficult to detect.
The LSB of a digital audio or video file tends to resemble noise.
The most significant bits tend to be grouped in blocks. For example, the ocean background has a large block of bits where r = 0110xxxx g = 1010xxxx b = 1110xxxx
Thus when encoding this data in the LSB there will be a repeating pattern: 0110xxxx1010xxxx1110xxxx.
Encryption randomizes this data so it looks like noise again.
c. Example : Popular Programs
S-Tools Image
Steghide .bmp .wav .au
MP3Stego .mp3
SnowText filesE-Mail
1. S-Tools One of the most reliable tools for steganography is
S-tools This program was created in 1994 by Andy Brown
There has been no updates since then because of its encryption algorithm, Nearly impossible to break
Includes programs that process GIF and BMP images, process audio files and will even hide information in the unused areas of the floppy diskettes
Why S-tools is so good for this!
4 different types of encryptions to choose from IDEA, DES, Triple DES, MDC
The password is entered and confirmed by the user and then is encrypted using the desired algorithm
To reveal any image one must know the password along with the encryption algorithm
This makes it extremely difficult to break even using a brute force attack.
3.1.1.2.2. Digital Fingerprint/signatures
Basic functionalityProcessesAsymmetric encryptionCertificationUser’s realisation
A. Basic Functionality
Digital Fingerprinting is an emerging technology to protect multimedia from unauthorized redistribution. It embeds a unique ID into each user's copy,
which can be extracted to help identify culprits when an unauthorized leak is found, that identifies the originator of a document.
It utilizes asymmetric encryption, where one key (private key) is used to create the signature code and a different but related key (public key) is used to verify it.
A. Basic Functionality
A powerful, cost-effective attack is the collusion attack from a group of users,
where the users combine their copies of the same content but with different fingerprints to generate a new version.
If designed improperly, the fingerprints can be attenuated or even removed by the collusion attack.
B. Processes
Message+
Signature
Message+
Signature
HashHash
DecryptSignature
With Sender’s Public Key
DecryptSignature
With Sender’s Public Key
SIGN hashWith Sender’s
Private key
SIGN hashWith Sender’s
Private key
Message+
signature
Message+
signature
COMPARECOMPARE
Calculated Hash
Calculated HashMessageMessage
Sender Receiver
HashHash
Signed Message
Sent thru’ Internet
if
OKSignatures
verified
Hash function : algorithm which creates a digital representation in the form of a hash result of a standard length which is usually much smaller than the message but substantially unique to it
Generally : Each individual generates his own key pair
• a pair of keys, namely a private key and a public key
[Public key known to everyone & Private key only to the owner]
Private Key – Used for making digital signature (ie. has to be saved, e.g. using a chip card with a PIN )
Public Key – Used to verify the digital signature Public key can be accessible for everyone,
• but its owner’s identity has to be identifiable without problems to guarantee authentication (certificate)
Not possible to generate the Private key by knowing someone’s Public key
B. Processes
RSA Key pair (including Algorithm identifier)
[2048 bit]
Private Key3082 010a 0282 0101 00b1 d311 e079 5543 0708 4ccb 0542 00e2 0d83 463d e493 bab6 06d3 0d59 bd3e c1ce 4367 018a 21a8 efbc ccd0 a2cc b055 9653 8466 0500 da44 4980 d854 0aa5 2586 94ed 6356 ff70 6ca3 a119 d278 be68 2a44 5e2f cfcc 185e 47bc 3ab1 463d 1ef0 b92c 345f 8c7c 4c08 299d 4055 eb3c 7d83 deb5 f0f7 8a83 0ea1 4cb4 3aa5 b35f 5a22 97ec 199b c105 68fd e6b7 a991 942c e478 4824 1a25 193a eb95 9c39 0a8a cf42 b2f0 1cd5 5ffb 6bed 6856 7b39 2c72 38b0 ee93 a9d3 7b77 3ceb 7103 a938 4a16 6c89 2aca da33 1379 c255 8ced 9cbb f2cb 5b10 f82e 6135 c629 4c2a d02a 63d1 6559 b4f8 cdf9 f400 84b6 5742 859d 32a8 f92a 54fb ff78 41bc bd71 28f4 bb90 bcff 9634 04e3 459e a146 2840 8102 0301 0001
Public Key3082 01e4 f267 0142 0f61 dd12 e089 5547 0f08 4ccb 0542 00e2 0d83 463d e493 bab6 0673 0d59 bf3e c1ce 4367 012a 11a8 efbc ccd0 a2cc b055 9653 8466 0500 da44 4980 d8b4 0aa5 2586 94ed 6356 ff70 6ca3 a119 d278 be68 2a44 5e2f cfcc 185e 47bc 3ab1 463d 1df0 b92c 345f 8c7c 4c08 299d 4055 eb3c 7d83 deb5 f0f7 8a83 0ea1 4cb4 3aa5 b35f 5a22 97ec 199b c105 68fd e6b7 a991 942c e478 4824 1a25 193a eb95 9c39 0a8a cf42 b250 1cd5 5ffb 6bed 6856 7b39 2c72 38b0 ee93 a9d3 7b77 3ceb 7103 a938 4a16 6c89 2aca da33 1379 c255 8ced 9cbb f2cb 5b10 f82e 6135 c629 4c2a d02a 63d1 6559 b4f8 cdf9 f400 84b6 5742 859d 32a8 f92a 54fb ff78 41bc bd71 28f4 bb90 bcff 9634 04de 45de af46 2240 8410 02f1 0001
B. ProcessesDigital signature creation (Sender Side) :
Generating message’s digest (hash result) and a given private key
• Result of the encryption: digital signature Sender send :
• Message with digital signature and certificate to receiver
Message HashFunction
HashResult
SigningFunction
PrivateKey
DigitalSignature
Message
To Verifier
Only Private KeyHolder Can Sign
create.vsd
B. ProcessesDigital signature verification (Receiver Side) :
Receiver wants to check• Integrity
– Generating hash result, compare it to the sender’s hash result and decrypting the message with the sender’s public key
• Authenticity– Can be checked by means of the certificate
HashFunction
HashResult
VerifyFunction
PublicKey
Anyone Can Verify
From Signer
DigitalSignature
Message
Valid Y/N?
sigver.vsd
C. Digital Signature Features
Signer Authentication : A signature should indicate who signed a document,
message or record, and should be difficult for another person to produce without authorization.
Message Authentication: The digital signature also identifies the signed
message, typically with far greater certainty and precision than paper signatures. Verifi ca tion reveals any tampering, since the comparison of the hash results
Affirmation Act : Signatures are legally binding
Efficiency : Allows for automation of modern Electronic Data
Interchange (EDI).
D. Advantages of Digital Signatures Data integrity
Digital signatures provide proof that the document or message has not been altered or tampered with.
Authentication of Identities Digital signatures make it easier to verify
the identity of senders and recipient. Concept of non-repudiation
This means that neither the sender nor the recipient can deny having sent or received the document.
Includes an automatic date and time stamp, which is critical in business transactions.
Increase the speed and accuracy of transactions
E. Disadvantages of Digital SignaturesTechnological Compatibility
Refers to standards and the ability of one digital signature system to "talk" to another. It is difficult to develop standards across a wide user base.
Security Concerns These efforts are perpetually hampered by
lost or borrowed passwords, theft and tampering, and vulnerable storage and backup facilities.
Legal Issues There is clear consensus that digital
signatures should be legally acceptable. However, many questions remain unanswered in the legal arena
F. Challenges
Institutional overhead The cost of establishing and utilizing
certification authorities, repositories, and other important services, as well as assuring quality in the performance of their functions.
Subscriber and relying Party CostsA digital signature will require
software, and will probably have to pay a certification authority some price to issue a certificate. Hardware to secure the subscriber’s private key also be advisable.
G. Digital Signatures Example : Text<Signed SigID=1>
Promissory Note
I, Mary Smith, promise to pay to the order of First Western Bank five thousand dollars and no cents ($5,000) on or before June 10, 1998, with
interest at the rate of fifteen per cent (15%) per annum.
Mary Smith, Maker
</Signed><Signature SigID=1 snID=smith082> 2AB3764578CC18946A29870F40198B240CD2302B2349802DE002342
B212990BA5330249C1D20774C1622D39</Signature>
Based on the concept of public key encryption.
Hashed version of image is encrypted using a private key.
Encrypted file provides a unique signature/fingerprint of the image which can be used to authenticate by decryption with public key.
Mainly used in transmission of images.
H. Example : For Image
I. Example : Digital Cameras
Epson Image Authentication System (IAS)The IAS software in the camera instantly
seals the captured images with an invisible digital fingerprint.
Verification of image is achieved by any PC with Image Authentication System software installed
3.1.2. ConfidentialityEncryption is a powerful tool for access
control and confidentiality protection
A. Encryption Algorithym
Data Encryption Standard (DES) The most widely used encryption scheme
DES is a block cipher – the plaintext is processed in 64-bit blocks
The key is 56-bits in length
Based on Feistel Cipher Structure Triple DES
Effective key length of 112/168 bits Advanced Encryption Standard (AES)
128-bit data, 128/192/256-bit keys
Stronger & faster than Triple-DES
Others
RSARC4RC6IDEAPGPPEMKerberos
B.Multimedia Encryption Approach Signal scrambling
Historical approach Not compatible with modern multimedia
compression Fast speed but low security
Total encryption with cryptographic ciphers Trivial solution High security but slow speed
Selective encryption Most popular approach today Limited in its range of application
Integrating encryption into entropy coding Complementary to selective encryption Very fast computation speed
Selective Encryption Select the most important coefficients and then
encrypt them with traditional ciphers such as DES
Advantages Lower complexity High security level provided by traditional cryptology Less error correction coding redundancy Compatible with existing software and hardware
modules
MediaCompression
System
Coefficient
Selection
CryptographicCipher
ErrorCorrection
Coding
DigitizedAudiovisual
data
Coefficients SelectedCoefficients
Non-selectedCoefficients
Transmission channel or storage media
3.1.3. IntegrityHashing process have discussed a little
bit at the confidentiality materials Hash algorithm :
3.1.4. Access Control See Encryption
3.1.5. Non repudiationThird party : search by yourself
3.2. Digital Rights Management A broad term used to describe a number of techniques
for restricting the free use and transfer of digital content. DRM is used in a number of media, but is most
commonly found in video and music files. They therefore reinterpret DRM to stand for Digital
Restrictions Management.
The identification and description of intellectual property, rights pertaining to works and to parties involved in their creation or administration (digital rights management)
The (technical) enforcement of usage restriction (digital management of rights).
3.2.1. A functional definition of DRM
Requirements Identification (unique identifier of the work)
Clear description (Metadata)
Usage rules
DRM tools Identify the work, the right holder
Describe the content
Allow use according to the rules
3.2.2. Requirement & Tools
3.2.3. DRM Technical Solution CONDITIONAL ACCESS (CA) SYSTEMS FOR SATELLITE, CABLE AND TERRESTRIAL TELEVISION NETWORKS DIGITAL RIGHTS MANAGEMENT (DRM) SYSTEMS FOR THE INTERNET COPY PROTECTION (CP) SYSTEMS FOR DIGITAL HOME NETWORKS
DVD PROTECTION
DIGITAL TAPE PROTECTION
DIGITAL INTERFACE PROTECTION IP MULTICAST SECURITY
SECURE MULTICAST APPLICATIONS
CORE PROBLEM AREA IN MULTICAST SECURITY
EVALUATION CRITERIA
CLASSIFICATION OF KEY MANAGEMENT SCHEMES
PERIODIC BATCH REKEYING WIRELESS NETWORKS AND MOBILE MEMBERS
TWO-TIER SERVER ARCHITECTURE
DESIGN CRITERIA
MOBILE MEMBER JOIN AND LEAVE
MOBILE MEMBER TRANSFER SECURITY OF WIRELESS LANS
WIRED EQUIVALENT PRIVACY (WEP)
WHAT’S WRONG WITH WEP?
IMPROVEMENTS ON WEP LEGAL SOLUTIONS
WORLD INTELLECTUAL PROPERTY ORGANIZATION (WIPO)
DIGITAL MILLENIUM COPYRIGHT ACT (DMCA) OF 1998
CONSUMER BROADBAND AND DIGITAL TELEVISION PROMOTION ACT (CBDTPA) OF 2002
CONSUMERS, SCHOOLS, AND LIBRARIES DIGITAL RIGHTS MANAGEMENT AWARENESS ACT OF 2003
3.2.3.1. Content Scrambling System (CSS)
One of the first and most widely contested DRM, used to encode DVD movie files. This system was developed by the DVD Consortium as
a tool to influence hardware manufacturers to produce only systems which didn't include certain features.
By releasing the encryption key for CSS only to hardware manufacturers who agreed not to include features such as digital-out, which would allow a movie to be copied easily, the DVD Consortium was essentially able to dictate hardware policy for the DVD industry.
Very quickly after the CSS DRM was implemented, its algorithm was broken.
3.2.3.2. DeCSS
Tools for making copies of CSS-encrypted movies and playing them on systems that otherwise would not be able to, such as some alternative operating systems.
The Digital Millennium Copyright Act in the United States makes it illegal to use systems such as DeCSS to bypass DRM limitations.
Similar acts have since been passed in many countries.
Many advocates in the computer science world see the DMCA as a major blow against creative freedom because of its overly harsh restrictions.
Game consoles (Nintendo, Sony Playstation, …)
Microsoft software (Genuine certificate verification)
Trial use of a software for a limited period of time
Online registration to activate the software
3.2.3.3. Software Example