F a c u l t y M e n t o r Cristina Videira Lopes School of Information & Computer Science

Steganography is one of the modern techniques for covert communication through the internet. In addition to providing confidentiality, it also enables the communication of large amounts of data without raising suspicion. This paper presents a novel technique for image steganography using Lehmer code that provides high capacity and better performance. Lehmer code is a way of encoding each possib...

In this note, we show that the encoding scheme discussed in [1] for quadrilateral meshes can be improved to 2.40 bits per vertex, using arithmetic coding. This is a considerable improvement over the current bound of 2.67 bits per vertex.

This paper shows three approaches for detecting steganograms with low change density. MP3Stego is a steganographic algorithm with a very low embedding rate. The attack presented here is a statistical analysis of block sizes. It is able to detect 0.001 % of steganographic payload in MP3 files. The second approach is the use of hash functions to combine sample categories for the chi-square attack...

This paper aims to find an effective and efficient information hiding method used for protecting secret information by embedding it in a cover media such as images. Finding the optimal set of the image pixel bits to be substituted by the secret message bits, such that the cover image is of high quality, is a complex process and there is an exponential number of feasible solutions. Two new ant-b...

The paper proposes breaks for the permutation methods adopted in the chaos-based image cryptosystems. By a careful examination on the most chaotic image cryptosystems we can find that the permutation process constitute the main step or, in some cases, the only step to create the confusion. It can be applied on the pixels or on the pixel bits. A recently proposed image encryption scheme based on...

We propose a new method of progressive transmission of continuous tone images using multi-level error diffusion method. Assuming that the pixels are ordered and the error is diffused to later pixels, multi-level error-diffused images are resolved into a multiple number of bit planes. In an image with 8 bits per pixel, the number of the bit planes that we construct is 9, and the 2-level, 3-level...

A comparative resource allocation analysis in terms of received bits-per-antenna spectral efficiency (SE) and energy (EE) downlink (DL) single-cell massive multiple-input multiple-output (mMIMO) non-orthogonal multiple access (NOMA) systems considering a BS equipped with many (M) antennas, while K devices operate single-antenna, the loading ρ=KM ranging 0<ρ≤2 is carried out under three differen...