Fragile Authentication Research Articles

A Semi-Fragile, Inner-Outer Block-Based Watermarking Method Using Scrambling and Frequency Domain Algorithms

Image watermarking is most often used to prove that an image belongs to someone and to make sure that the image is the same as was originally produced. The type of watermarking used for the detection of originality and tampering is known as authentication-type watermarking. In this paper, a blind semi-fragile authentication watermarking method is introduced. Although the main concern in this paper is authenticating the image, watermarking for proving ownership is additionally implemented. The method considers the image as two main parts: an inner part and an outer part. The inner and outer parts are divided into non-overlapping blocks. The block size of the inner and outer part are different. The outer blocks have a greater area than the inner blocks so that their watermark-holding capacity is greater, providing enough robustness for semi-fragility. The method is semi-fragile and the watermarked image is authenticated despite the JPEG being compressed to 75% quality. The embedded watermark also survives innocent types of image operations, such as intensity adjustment, histogram equalization and gamma correction. Semi-fragile and selectively fragile authentication is valuable and in high demand specifically because it survives these innocent image operations while detecting ill-intentioned tampering. In this work, we embed a binary watermark into the inner and outer parts of images using a scrambling algorithm, discrete wavelet transform (DWT) and discrete cosine transform (DCT) in the blocks. The proposed methodology has high image quality after watermarking, with a PSNR value of 40.577, and high quality is also achieved after JPEG compression. The embedding process provides acceptable image quality after tamper attacks, including JPEG compression, Gaussian noise, average filtering, and scaling attacks with PSNR values greater than 29. Experimental results obtained show that the proposed semi-fragile watermarking algorithm is more robust, secure and resistant than other algorithms in the literature.

Image integrity authentication scheme based on fixed point theory.

Based on the fixed point theory, this paper proposes a new scheme for image integrity authentication, which is very different from digital signature and fragile watermarking. By the new scheme, the sender transforms an original image into a fixed point image (very close to the original one) of a well-chosen transform and sends the fixed point image (instead of the original one) to the receiver; using the same transform, the receiver checks the integrity of the received image by testing whether it is a fixed point image and locates the tampered areas if the image has been modified during the transmission. A realization of the new scheme is based on Gaussian convolution and deconvolution (GCD) transform, for which an existence theorem of fixed points is proved. The semifragility is analyzed via commutativity of transforms, and three commutativity theorems are found for the GCD transform. Three iterative algorithms are presented for finding a fixed point image with a few numbers of iterations, and for the whole procedure of image integrity authentication; a fragile authentication system and a semifragile one are separately built. Experiments show that both the systems have good performance in transparence, fragility, security, and tampering localization. In particular, the semifragile system can perfectly resist the rotation by a multiple of 90° flipping and brightness attacks.

A New Fragile Watermarking Based on Chaos

For existing airspace fragile authentication watermarking algorithm positioning accuracy and security issues, this paper presents a fully-fragile watermarking based on chaos for the integrity of the image content authentication and tamper localization. The algorithm uses the original image block, the calculation of each pixel in the image block high-bit gray value as the image feature watermark information. The chaotic sequence is encrypted and determines the position of the watermark bit is embedded watermark information, tampering with the positioning accuracy of an image block of 2 × 2 pixels. Experimental results show that the algorithm is simple, safe, with good practice.

A Grayscale Image Fragile Watermark Authentication System in Spatial-Domain

This study deals with devising and implementing a novel technique for image authentication and secured message transmission based on hiding large volume of data into gray scale images. A grayscale image fragile watermark authentication system in spatial-domain is proposed. First it preprocesses the watermark image and resizes it to a quarter of the size of the original image. Then, it generates a random key matrix K and 128bit message authentication code from the original image. It replaces the 128bit message authentication code for the former 128bit of K to obtain a new key matrix KH. Then, it calculates the embedded position P=KHi xor (b7,b6,b5.b4) i MOD 3. b7,b6,b5,b4 are the high 4 bits of the original images pixel. It embeds the watermark image according to P value to the lower 4 bits of the original images pixel. The system is made in experiment. The result shows the system has good imperceptibility.

Image authentication using generalised finite automata

An effective technique for combined fragile and semi-fragile image authentication is presented. The authentication signature is extracted from image representation in the automata domain, unlike most conventional methods that are based on frequency domain. In the automata domain, the image is represented in terms of its perceptual self-similarity and can therefore survive high JPEG compression ratios. This method is also capable of changing the degree of fragility by setting the value of the image self-similarity parameter α. Furthermore, the proposed technique features an extremely compact signature length while maintaining a rather simple implementation. Experimental results are presented to demonstrate the effectiveness of the proposed technique.

Toward secure public-key blockwise fragile authentication watermarking

The authors describe some weaknesses of public-key blockwise fragile authentication watermarkings and the means to make them secure. Wong's original algorithm as well as a number of its variant techniques are not secure against a mere block cut-and-paste or the well known birthday attack. To make them secure, some schemes have been proposed to make the signature of each block depend on the contents of its neighbouring blocks. The authors attempt to maximise the change localisation resolution using only one dependency per block with a scheme they call hash block chaining version 1 (HBC1). They then show that HBC1, as well as any neighbour content-dependent scheme, are susceptible to another forgery technique that they have named a transplantation attack. They also show a new kind of birthday attack that can be effectively mounted against HBC1. To thwart these attacks, they propose using a nondeterministic digital signature together with a signature-dependent scheme (HBC2). Finally, they discuss the advantages of using discrete logarithm signatures instead of RSA for watermarking.