Recent Developments on Multimedia and Secure Networking Technologies Chair Professor Chin-Chen Chang Feng Chia University National Chung Cheng University National Tsing Hua University

Multimedia (Watermarking) Classifications: Visible watermarking Invisible watermarking Robust watermarking Semi-fragile watermarking Fragile watermarking

Multimedia (Watermarking) (Cont.) Visible watermarking Easy to embed Clear to see watermark

Multimedia (Watermarking) (Cont.) Invisible watermarking Requirements: Good visual quality of watermarked image Robustness Watermarking Original image Watermarked image Watermark

Multimedia (Image authentication) Requirements: Detect the tampered area Try to restore the tampered area Solutions: Hamming codes Image Tampered image Detected image Restored image

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

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

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 …

Multimedia (Secret sharing) Classification: Meaningless shadows Meaningful shadows Requirements: Unexpected user can not see the secret image Good visual quality of reconstructed secret image

Multimedia (Secret sharing) (Cont.) Shadow size: 256  256 Image size: 512  512 Reconstructing (2,4)-threshold secret sharing scheme PSNR=24 dB

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

Multimedia (Secret sharing) (Cont.) Reconstructing Hiding Stego-image Reconstructed secret image Secret image Stego-image (2, n)-threshold secret sharing scheme Stego-image

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

Multimedia (Visual cryptography) (Cont.) Stacking Shadow 1 Shadow 2 Secret

Multimedia (Visual cryptography) (Cont.) Stacking Shadow 1 Shadow 2 Secret

Multimedia (Visual cryptography) (Cont.) Rotating 40o Stacking Stacking Share 1 Share 2 Secret 1 “VISUAL” Secret 2 “SECRET”

Multimedia (Threshold) Requirements: Segment the objects on image Low computation cost Threshold value T=41 Class 1 Class 2 Original image Segmented image Histogram

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

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)

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

Secure Networking (Cont.) Authentication in WLAN Requirements: Prevent impersonation attacks Protect personal privacy Solutions: Using mutual authentication Feasible computational complexity Using session keys

Secure Networking (Cont.) Key Exchange Remote Server IC Card Issuing Center Authentication Center (AC) 2. Service request 3. Authentication and key exchange 1. Issue an IC card Users

Secure Networking (Cont.) Requirements: Freely choose identity and password Password modification Mutual authentication Common session key distribution Reduce computation cost

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