31-07-2014, 11:30 AM
An Integrity Verification System for Images using Hashing and Watermarking
An Integrity.pptx (Size: 310.99 KB / Downloads: 11)
Problem Definition
Integrity Verification is verifying the originality of an object
Conventional methods for integrity verification based on watermarking are not robust against even simple attacks
Integrity verification is done in a more secure and robust way by hashing in cryptography.
Hash function
Hash function is a computationally efficient one-way function mapping an object of arbitrary size, to binary string of some fixed length called hash value.
Cryptographic hash functions
Perceptual hash functions
Image watermarking
Watermarking is the process that embeds data called a watermark, into a multimedia object such that watermark can be detected or extracted later for some useful purpose.
Invisible, semi-fragile, blind watermarking is used here for Integrity Verification
Improvements for Reducing BER
For overcoming the problem of low robustness of the watermarking method against JPEG compression, RS coding, BCH coding and spread spectrum coding of hash are tried.
Spreading the hash by 16 was observed to give excellent robustness against JPEG compression up to quality level 60, and is used for forming the system.
Conclusion
FJLT based hashing and DCT based watermarking together forms a Robust Integrity Verification System for both gray level and color Images
This method gives BER very close to zero for JPEG compression up to quality level 60 and by keeping a threshold at 0.1, the system will be able to detect all malicious manipulations.