Multimedia & Its Security

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Multimedia & its Security

By

Muhammad Akram

L1S09MSTS0009

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What is Multimedia

Multimedia is a computer-based interactive communications process that incorporates text, graphics, sound, animation, and

video

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Focus on

• Authentication of Digital image

• Protecting Audio Video Contents

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MotivationSeeing is believing … or is it?

UCP new Campus at Gilgit

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Easy to be deceived

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Categories of Image Tampering

• There are three main categories of image tampering:

• Enhancing

• Compositing

• Copy/Move

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Enhancing

• Changing the color of objects

• Changing the weather conditions

• Blurring shadow out objects

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Compositing

Combining two or Combining two or more images to more images to create a new imagecreate a new image

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Copy-Move

Copying regions of the original image and pasting into other areas.

The yellow area has been copied and moved to cover up the truck.

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What can be done to protect digital images?

•Watermarking• Fragile watermarks• Semi-fragile watermarks• Self-embedding watermarks• Digital cameras with watermarking

capabilities

•Digital Fingerprinting/Signatures• Digital cameras with fingerprinting

capabilities

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Digital Watermarking

• The basic concept of digital watermarking an image is that a low level signal is placed directly into the image data.

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Fragile Watermarks

• Fragile watermarks are designed to detect every possible change in pixel values .

• Variety of Techniques but in most cases, the watermark is embedded in the least significant bit (LSB) of the image.

• Advantages: Pick up all image manipulations – malicious and non-malicious

• Disadvantages: Too sensitive

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Semi-Fragile Watermarks• They 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.

– Divide image into blocks, construct watermark in DCT domain from pseudo-random zero-mean unit variance Gaussian numbers, take the inverse DCT and insert into the image.

• Advantage: less sensitive than fragile watermarks

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Self-Embedding

• Self-embedding allows tamper detection and recovery of missing information.

• General concept is that the image is embedded in itself in an encrypted form.

• Advantage: Potential for original data to be retrieved.

• Disadvantage: Tampering with the image can remove blocks of the original image making retrieval of content impossible

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Digital Fingerprints/Signatures

• 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.

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Protecting AV contents

• Audio Video streaming • Techniques to protect Audio Video contents

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Audio Video Streaming

• Audio video streaming is a multimedia which is continuous received by end user.

Media and broadcasting over the internet is called live streaming.

• Application of AV streaming

IPTV , WebTV, Web Radio, Video conferencing, Tele medicine

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Security requirements for AV contents Transport layer

• Access control and authentication:

Implemented on the access network to prevent unauthorized access and utilization of resources.

In network access, the subscriber/subscriber terminal should be identified and authenticated.

• Authenticity of network entities:

The network should have the ability to verify the identity to establish the trust relationship among the network entities.

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• Protection of data integrity and availability: The carrier network should guarantee the integrity,

availability of data stored or delivered in the network.• Accountability of data packets:Prevention of all bad behaviours is required. • Multicast security protection: Either IP multicast or application layer multicast required

the availability of the key (such as the multicast source, key nodes running multicast protocols etc), verification of identities of the multicast source, the control of the multicast group members, etc.

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Security requirements for IPTV Content level

• The security requirements for IPTV content concern with three entities: content provider, service provider and end consumer. For different purpose, the technologies of DRM can be used by content provider or service provider, separately or together

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Security requirements for content provider

• Copyrights protection for contents: IPTV content provider should use digital watermark technologies to protect the copyrights of contents they owned or sold.

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Security requirements for service provider

• Copyrights protection for contents:

DRM technology to prevent the under way programs being spied, copied, and redistributed illegally.

• Protection for legality of contents:

Contents broadcast via any network must be compliant with law/regulatory requirements issued by national or local authorities, e.g. Acts about content rating or children’s protection.

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Techniques to protect AV contents

• Encryption

• CAS (conditional Access system)

• DRM digital right management

• Watermarking

Future Research continue

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