Robust Image Watermarking Based on Psychovisual Threshold

Because of the facility of accessing and sharing digital images through the internet, digital images are often copied, edited and reused. Digital image watermarking is an approach to protect and manage digital images as intellectual property. The embedding of a natural watermark based on the properties of the human eye can be utilized to effectively hide a watermark image. This paper proposes a watermark embedding scheme based on the psychovisual threshold and edge entropy. The sensitivity of minor changes in DCT coefficients against JPEG quantization tables was investigated. A watermark embedding scheme was designed that offers good resistance against JPEG image compression. The proposed scheme was tested under different types of attacks. The experimental results indicated that the proposed scheme can achieve high imperceptibility and robustness against attacks. The watermark recovery process is also robust against attacks

Cryptanalysis and Secure Implementation of Modern Cryptographic Algorithms

Cryptanalytic attacks can be divided into two classes: pure mathematical attacks and Side Channel Attacks (SCAs). Pure mathematical attacks are traditional cryptanalytic techniques that rely on known or chosen input-output pairs of the cryptographic function and exploit the inner structure of the cipher to reveal the secret key information. On the other hand, in SCAs, it is assumed that attackers have some access to the cryptographic device and can gain some information from its physical implementation. Cold-boot attack is a SCA which exploits the data remanence property of Random Access Memory (RAM) to retrieve its content which remains readable shortly after its power has been removed. Fault analysis is another example of SCAs in which the attacker is assumed to be able to induce faults in the cryptographic device and observe the faulty output. Then, by careful inspection of faulty outputs, the attacker recovers the secret information, such as secret inner state or secret key. Scan-based Design-For-Test (DFT) is a widely deployed technique for testing hardware chips. Scan-based SCAs exploit the information obtained by analyzing the scanned data in order to retrieve secret information from cryptographic hardware devices that are designed with this testability feature. In the first part of this work, we investigate the use of an off-the-shelf SAT solver, CryptoMinSat, to improve the key recovery of the Advance Encryption Standard (AES-128) key schedules from its corresponding decayed memory images which can be obtained using cold-boot attacks. We also present a fault analysis on both NTRUEncrypt and NTRUSign cryptosystems. For this specific original instantiation of the NTRU encryption system with parameters $(N,p,q)$, our attack succeeds with probability $\approx 1-\frac{1}{p}$ and when the number of faulted coefficients is upper bounded by $t$, it requires $O((pN)^t)$ polynomial inversions in $\mathbb Z/p\mathbb Z[x]/(x^{N}-1)$. We also investigate several techniques to strengthen hardware implementations of NTRUEncrypt against this class of attacks. For NTRUSign with parameters ($N$, $q=p^l$, $\mathcal{B}$, \emph{standard}, $\mathcal{N}$), when the attacker is able to skip the norm-bound signature checking step, our attack needs one fault to succeed with probability $\approx 1-\frac{1}{p}$ and requires $O((qN)^t)$ steps when the number of faulted polynomial coefficients is upper bounded by $t$. The attack is also applicable to NTRUSign utilizing the \emph{transpose} NTRU lattice but it requires double the number of fault injections. Different countermeasures against the proposed attack are also investigated. Furthermore, we present a scan-based SCA on NTRUEncrypt hardware implementations that employ scan-based DFT techniques. Our attack determines the scan chain structure of the polynomial multiplication circuits used in the decryption algorithm which allows the cryptanalyst to efficiently retrieve the secret key. Several key agreement schemes based on matrices were recently proposed. For example, \'{A}lvarez \emph{et al.} proposed a scheme in which the secret key is obtained by multiplying powers of block upper triangular matrices whose elements are defined over $\mathbb{Z}_p$. Climent \emph{et al.} identified the elements of the endomorphisms ring $End(\mathbb{Z}_p \times \mathbb{Z}_{p^2})$ with elements in a set, $E_p$, of matrices of size $2\times 2$, whose elements in the first row belong to $\mathbb{Z}_{p}$ and the elements in the second row belong to $\mathbb{Z}_{p^2}$. Keith Salvin presented a key exchange protocol using matrices in the general linear group, $GL(r,\mathbb{Z}_n)$, where $n$ is the product of two distinct large primes. The system is fully specified in the US patent number 7346162 issued in 2008. In the second part of this work, we present mathematical cryptanalytic attacks against these three schemes and show that they can be easily broken for all practical choices of their security parameters

MOCAST 2021

The 10th International Conference on Modern Circuit and System Technologies on Electronics and Communications (MOCAST 2021) will take place in Thessaloniki, Greece, from July 5th to July 7th, 2021. The MOCAST technical program includes all aspects of circuit and system technologies, from modeling to design, verification, implementation, and application. This Special Issue presents extended versions of top-ranking papers in the conference. The topics of MOCAST include:Analog/RF and mixed signal circuits;Digital circuits and systems design;Nonlinear circuits and systems;Device and circuit modeling;High-performance embedded systems;Systems and applications;Sensors and systems;Machine learning and AI applications;Communication; Network systems;Power management;Imagers, MEMS, medical, and displays;Radiation front ends (nuclear and space application);Education in circuits, systems, and communications

BRDF Editor

Název: BRDF Editor Autor: Jan Waltl Katedra: Katedra softwaru a výuky informatiky Vedoucí práce: RNDr. Josef Pelikán, Katedra softwaru a výuky informatiky Abstrakt: Cílem této práce je vytvořit prostředí pro tvorbu a editaci materiálů v podobě bidirectional reflectance functions(BRDF) (obousměrné distribuční funkce odrazu světla). Výsledkem práce je grafická aplikace umožňující psaní těchto funkcí, náhled jejich chování ve formě 2D grafů a otestování v jednoduchých prostředích. Aby se toho dosáhlo, bude část programu využívat grafické karty skrze OpenCL. Tento přístup by měl umožnit interaktivní práci s funkcemi. Součástí je imple- mentace známých algoritmů sledování paprsků, které právě dokáží vykreslovat realisticky vypadající obrázky včetně nepřímého osvětlení. Tyto algoritmy budou používat metodu vzorkování dle důležitosti, včetně možnosti napsaní vlastního vzorkování pro dané BRDF. Klíčová slova: BRDF OpenCL photo-realistic rendering path tracing GPU iiiTitle: BRDF Editor Author: Jan Waltl Department: Department of Software and Computer Science Education Supervisor: RNDr. Josef Pelik'an, Department of Software and Computer Science Education Abstract: The goal of this thesis is to create a working environment for the development and testing of bidirectional reflectance functions (BRDFs). The result of our work is a graphical application that offers tools to write these BRDFs, see how they behave on dynamic 2D graphs and in simple scenes. To achieve this, we created a general framework for physically based rendering algorithms. With the help of accelerating in hardware, in particular graphics cards(GPUs), we use OpenCL API to boost performance and allow interactive work with the developed functions. As part of the work, we implemented the path tracing algorithm capable of rendering realistic-looking scenes with indirect lighting from area lights and an environment light. The used algorithm uses importance sampling to greatly improve convergence speed and allows writing these custom sampling strategies for the written BRDFs and seeing how they match the BRDF, thus testing their effectiveness. Keywords: BRDF OpenCL photo-realistic rendering path tracing GPU iiiKatedra softwaru a výuky informatikyDepartment of Software and Computer Science EducationFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Implementing RLWE-based Schemes Using an RSA Co-Processor

We repurpose existing RSA/ECC co-processors for (ideal) lattice-based cryptography by exploiting the availability of fast long integer multiplication. Such co-processors are deployed in smart cards in passports and identity cards, secured microcontrollers and hardware security modules (HSM). In particular, we demonstrate an implementation of a variant of the Module-LWE-based Kyber Key Encapsulation Mechanism (KEM) that is tailored for high performance on a commercially available smart card chip (SLE 78). To benefit from the RSA/ECC co-processor we use Kronecker substitution in combination with schoolbook and Karatsuba polynomial multiplication. Moreover, we speed-up symmetric operations in our Kyber variant using the AES co-processor to implement a PRNG and a SHA-256 co-processor to realise hash functions. This allows us to execute CCA-secure Kyber768 key generation in 79.6 ms, encapsulation in 102.4 ms and decapsulation in 132.7 ms

Image Quality Metrics for Stochastic Rasterization

We develop a simple perceptual image quality metric for images resulting from stochastic rasterization. The new metric is based on the frequency selectivity of cortical cells, using ideas derived from existing perceptual metrics and research of the human visual system. Masking is not taken into account in the metric, since it does not have a significant effect in this specific application. The new metric achieves high correlation with results from HDR-VDP2 while being conceptually simple and accurately reflecting smaller quality differences than the existing metrics. In addition to HDR-VDP2, measurement results are compared against MS-SSIM results. The new metric is applied to a set of images produced with different sampling schemes to provide quantitative information about the relative quality, strengths, and weaknesses of the different sampling schemes. Several purpose-built three-dimensional test scenes are used for this quality analysis in addition to a few widely used natural scenes. The star discrepancy of sampling patterns is found to be correlated to the average perceptual quality, even though discrepancy can not be recommended as the sole method for estimating perceptual quality. A hardware-friendly low-discrepancy sampling scheme achieves generally good results, but the quality difference to simpler per-pixel stratified sampling decreases as the sample count increases. A comprehensive mathematical model of rendering discrete frames from dynamic 3D scenes is provided as background to the quality analysis

Intelligent detectors

Die vorliegende Arbeit stellt eine Basis zur Entwicklung von On-Board Software für astronomische Satelliten dar. Sie dient als Anleitung und Nachschlagewerk und zeigt anhand der Projekte Herschel/PACS und SPICA/SAFARI, wie aus den Grundlagen weltraumtaugliche Flugsoftware entsteht. Dazu gehören das Verstehen des wissenschaftlichen Zwecks, also was soll wie gemessen werden und wofür ist das gut, sowie die Kenntnis der physikalischen Eigenschaften des Detektors, das Beherrschen der mathematischen Operationen zur Verarbeitung der Daten und natürlich auch die Berücksichtigung der Umstände, unter welchen der Detektor zum Einsatz kommt.This thesis contains the knowledge and a good deal of experience that are necessary for the development of such astronomical on-board software for satellites. The key elements in the development are the understanding of the scientific purpose, knowledge of the physical properties of the detector, the comprehension of the mathematical operations involved in data processing and the consideration of the technical and observational circumstances

Publications of the Jet Propulsion Laboratory, 1977

This bibliography cites 900 externally distributed technical reports released during calendar year 1977, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. Report topics cover 81 subject areas related in some way to the various NASA programs. The publications are indexed by: (1) author, (2) subject, and (3) publication type and number. A descriptive entry appears under the name of each author of each publication; an abstract is included with the entry for the primary (first-listed) author

Signal separation of musical instruments: simulation-based methods for musical signal decomposition and transcription

This thesis presents techniques for the modelling of musical signals, with particular regard to monophonic and polyphonic pitch estimation. Musical signals are modelled as a set of notes, each comprising of a set of harmonically-related sinusoids. An hierarchical model is presented that is very general and applicable to any signal that can be decomposed as the sum of basis functions. Parameter estimation is posed within a Bayesian framework, allowing for the incorporation of prior information about model parameters. The resulting posterior distribution is of variable dimension and so reversible jump MCMC simulation techniques are employed for the parameter estimation task. The extension of the model to time-varying signals with high posterior correlations between model parameters is described. The parameters and hyperparameters of several frames of data are estimated jointly to achieve a more robust detection. A general model for the description of time-varying homogeneous and heterogeneous multiple component signals is developed, and then applied to the analysis of musical signals. The importance of high level musical and perceptual psychological knowledge in the formulation of the model is highlighted, and attention is drawn to the limitation of pure signal processing techniques for dealing with musical signals. Gestalt psychological grouping principles motivate the hierarchical signal model, and component identifiability is considered in terms of perceptual streaming where each component establishes its own context. A major emphasis of this thesis is the practical application of MCMC techniques, which are generally deemed to be too slow for many applications. Through the design of efficient transition kernels highly optimised for harmonic models, and by careful choice of assumptions and approximations, implementations approaching the order of realtime are viable.Engineering and Physical Sciences Research Counci