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Recent Developments on Multimedia and Secure

Networking Technologies

Chair Professor Chin-Chen ChangFeng Chia UniversityNational Chung Cheng University National Tsing Hua University

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Multimedia (Watermarking) Classifications:

Visible watermarking Invisible watermarking Robust watermarking Semi-fragile watermarking Fragile watermarking

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Multimedia (Watermarking) (Cont.) Visible watermarking

Easy to embed Clear to see watermark

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Multimedia (Watermarking) (Cont.) Invisible watermarking

Requirements: Good visual quality of watermarked image Robustness

Watermarking

Watermarked imageOriginal imageWatermark

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Multimedia (Image authentication) Requirements:

Detect the tampered area Try to restore the tampered area

Solutions: Hamming codes

Image Tampered image Detected image Restored image

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Multimedia (Steganography) Classification:

The target of modification Frequency domain (e.g. DCT, DWT, DFT) Spatial domain (e.g. pixel values) Compression domain (e.g. VQ, LAC, SOC)

Stego image restoration Irreversible data hiding Reversible data hiding

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Multimedia (Steganography) (Cont.) Irreversible data hiding

Requirements: High capacity Good visual quality of stego images

Solutions: Using Sudoku Using wet paper codes concept Using Hamming codes

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Multimedia (Steganography) (Cont.) Reversible

Requirements: Fully reconstructing cover image Good visual quality of stego image High capacity

Solutions: Data hiding in VQ indices Data hiding in LAC codes Data hiding in SOC codes …

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Multimedia (Secret sharing) Classification:

Meaningless shadows Meaningful shadows

Meaningless shadows Requirements:

Unexpected user can not see the secret image

Good visual quality of reconstructed secret image

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Multimedia (Secret sharing) (Cont.)

Shadow size: 256 256Image size: 512 512

Sharing

Reconstructing

PSNR=24 dB

(2,4)-threshold secretsharing scheme

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Multimedia (Secret sharing) (Cont.) Meaningful shadows

Requirements: Good visual quality of stego image Secret image extraction and reconstruction

Solutions: Applying steganography techniques Applying image authentication mechanisms

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Multimedia (Secret sharing) (Cont.)

Secret image

Stego-image

Stego-image

Hiding

Reconstructed secret image

Reconstructing

(n,2)-threshold secretsharing scheme

Stego-image

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Multimedia (Visual cryptography) Requirements:

Secret message delivery Unexpected user can not see the

message from an individual share Solutions:

Using shadow patterns Using meaningful shadow images Using Circle Shares

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Multimedia (Visual cryptography) (Cont.)

Shadow 1 Shadow 2

Secret

Staking

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Multimedia (Visual cryptography) (Cont.)

Shadow 1 Shadow 2

Secret

Staking

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Multimedia (Visual cryptography) (Cont.)

Share 1 Share 2

Secret 1 “VISUAL” Secret 2 “SECRET”

Staking Staking

Rotating 40o

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Multimedia (Threshold) Requirements:

Segment the objects on image Low computation cost

Original image Segmented image

Threshold value T=53

Histogram

Class 2Class 1

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Secure Networking Fast Computation Algorithms for Cryptography

Requirements: Large number computations Low computation cost

Solutions: Fast division algorithm using residue number system (RNS) Fast conversion algorithms in RNS using Aryabhata remainder theorem (ART) Fast RNS modular multiplication and exponentiation algorithms

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Secure Networking (Cont.) Secure Communication

Secure E-mail protocols Requirements

Reduce the computation cost of client devices Achieve perfect forward secrecy

Solutions: Using low cost functions (e.g. one-way hash

functions)

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Secure Networking (Cont.) Anonymity for Roaming Service

Requirements: Avoid possible attacks (e.g. replay attacks,

forgery attacks, known-key attacks) Achieve the property of anonymity

Solutions: Using low cost functions Using smart card Using nonce to replace timestamp

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Secure Networking (Cont.) Authentication in WLAN

Requirements: Prevent impersonation attacks Protect personal privacy

Solutions: Using mutual authentication Feasible computational complexity Using session keys

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Secure Networking (Cont.) Key Exchange

2. Service request1. Issue an IC card

Users

Authentication Center (AC)IC Card Issuing Center

Remote Server

3. Authentication and key exchange

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Secure Networking (Cont.) Requirements:

Freely choose identity and password Password modification Mutual authentication Common session key distribution Reduce computation cost

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Secure Networking (Cont.) E-commerce Application

Electronic check Payer’s identity appending E-checks generation Payer and payee verification

E-traveler’s check Unique identity for the e-traveler’s check E-traveler’s check can only be generated by check –issuing bank or an authorized organization