10 research outputs found
Uncertainty of a RMS Power Detector
No full textThe accuracy of a true-RMS detector board based on the Analog Devices LTC5596 is determined by measuring the input power and the output voltage. A number of samples of the output voltage is taken and the mean and standard deviation is shown. These measurements are done for single-tone excitation with a direct connection and over-the-air setup, and for multi-tone excitation with a direct connection. It has been demonstrated that the detector response worsens with over-the-air excitation, resulting in a doubling of the standard deviation in the output voltage compared to a direct connection. With multi-tone excitation, the standard deviation is fifteen times higher than with a direct connection. Additionally, with multi-tone excitation the mean output voltage is lower than with the same input power as single-tone. This discrepancy increases with the amount of tones.A Keysight Advanced Design System simulation is also presented for the three different measurement setups. With the use of a Monte Carlo simulation uncertainty bounds between the function generator and the power detector are made. Furthermore the noise of the power detector is simulated and sources of noise analyzed
„Ostatni Żydzi Polski” czy ostatnia lewica po polsku? Wokół książki Davida Kowalskiego „Polens letzte Juden. Herkunft und Dissidenz um 1968”
No full textIn his PhD thesis entitled Polens letzte Juden: Herkunft und Dissidenz um 1968 [Poland’s Last Jews: Descent and Dissidence around 1968], which was published in 2018, David Kowalski analyses “the relation between the milieu of descent” – in the sociological sense – and “oppositional activity”. The milieu in question refers to the students in post-war Poland who were part of the Club of the Seekers of Contradictions (Klub Poszukiwaczy Sprzeczności), among them Jan Tomasz Gross and Adam Michnik as its co-founders, the author’s parents, Irena Grudzińska Gross and others. Members of the club met at the beginning of the 1960s on a regular basis to discuss books and organize political debates. For the author, the category of milieu is key to understanding the question of why many students of Jewish origin were engaged in the protest movement of 1968 in Poland. The students’ political activity points to “the last revolt of Jewish hope in communism”, as stated in the conclusion of the book. Kowalski’s work is based on archival sources from the Central Archives of Modern Records in Warsaw (Archiwum Akt Nowych) and the archives of the Institute of National Remembrance in Warsaw (Instytut Pamięci Narodowej) as well as on twenty interviews with dissidents. The author also conducted interviews with his parents (23 December 2014). He spoke to all people involved once, except Jan Tomasz Gross, whom he interviewed twice, and Irena Grudzińska-Gross, whom he interviewed on three occasions (in June 2010, on 30 September 2012 and on 11 September 2014). To understand how the author has reached his conclusions, I examine his argument through an analytical framework that I have adopted from my dissertation advisor Ingrid Gilcher-Holtey, who specializes in 1968. This analytical method requires reconstruction of the author’s argumentation, followed by its deconstruction.W pracy doktorskiej pt. Polens letzte Juden. Herkunft und Dissidenz um 1968 [Ostatni Żydzi Polski. Pochodzenie i postawa dysydencka związane z rokiem 1968], która ukazała się w 2018 roku, jej autor David Kowalski analizuje „związek między środowiskiem pochodzenia” – w sensie socjologicznym – „i działalnością opozycyjną”. O jakie środowisko chodzi? O żyjących w powojennej Polsce studentów, którzy byli członkami i członkiniami Klubu Poszukiwaczy Sprzeczności, w tym Jana Tomasza Grossa i Adama Michnika jako współzałożycieli tego klubu, o rodziców autora książki, o Irenę Grudzińską-Gross oraz innych. Od początku lat sześćdziesiątych ubiegłego wieku członkowie Klubu spotykali się regularnie na dyskusjach i debatach politycznych. Kategoria „środowiska” jest dla Kowalskiego kluczem do odpowiedzi na pytanie, dlaczego w ruch protestu ‘68 roku w Polsce zaangażowało się wyjątkowo wielu studentów żydowskiego pochodzenia. W konkluzji książki czytamy, że polityczna aktywność studentów wskazuje na „ostatni zryw żydowskiej nadziei na komunizm”. Praca Kowalskiego opiera się na źródłach archiwalnych (zbiorach Instytutu Pamięci Narodowej i Archiwum Akt Nowych) oraz na dwudziestu rozmowach z dysydentami ‘68 roku. Autor przeprowadził też rozmowę ze swoimi rodzicami (23 grudnia 2014 roku). Z większością wymienionych rozmawiał raz, tylko z Janem Grossem dwa razy, a z Ireną Grudzińską-Gross – trzy razy (w czerwcu 2010 roku, 30 września 2012 roku i 11 września 2014 roku). Aby zrozumieć, jak autor doszedł do sformułowanych przez siebie konkluzji, przedstawię analizę jego tekstu przeprowadzoną za pomocą instrumentarium analitycznego, którego nauczyłam się od Ingrid Gilcher-Holtey, promotorki mojego doktoratu i badaczki roku 1968. Jak twierdzi Gilcher-Holtey, rekonstrukcja zdarzeń powinna poprzedzać ich dekonstrukcję – taką też perspektywę przyjmuję w tym artykule
Finding Bugs and Features Using Cryptographically-Informed Functional Testing
No full textIn 2018, Mouha et al. (IEEE Trans. Reliability, 2018) performed a postmortem investigation of the correctness of reference implementations submitted to the SHA3 competition run by NIST, finding previously unidentified bugs in a significant portion of them, including two of the five finalists. Their innovative approach allowed them to identify the presence of such bugs in a black-box manner, by searching for counterexamples of expected cryptographic properties of the implementations under test. In this work, we extend their approach to key encapsulation mechanisms (KEMs) and digital signature schemes (DSSs). We perform our tests on multiple versions of the LibOQS collection of post-quantum schemes to capture implementations at different points of the recent Post-Quantum Cryptography Standardization Process run by NIST. We identify multiple bugs, ranging from software bugs (segmentation faults, memory overflows) to cryptographic bugs, such as ciphertext malleability in KEMs claiming IND-CCA security. We also observe various features of KEMs and DSSs that do not contradict any security guarantees but could appear counter-intuitive. Finally, we compare this methodology with a traditional fuzzing campaign against LibOQS and SUPERCOP, observing that traditional fuzzing harnesses appear less effective in surfacing software and logical bugs
Finding Bugs and Features Using Cryptographically-Informed Functional Testing
No full textIn 2018, Mouha et al. (IEEE Trans. Reliability, 2018) performed a post-mortem investigation of the correctness of reference implementations submitted to the SHA3 competition run by NIST, finding previously unidentified bugs in a significant portion of them, including two of the five finalists. Their innovative approach allowed them to identify the presence of such bugs in a black-box manner, by searching for counterexamples of expected cryptographic properties of the implementations under test. In this work, we extend their approach to key encapsulation mechanisms (KEMs) and digital signature schemes (DSSs). We perform our tests on multiple versions of the LibOQS collection of post-quantum schemes to capture implementations at different points of the recent Post-Quantum Cryptography Standardization Process run by NIST. We identify multiple bugs, ranging from software bugs (segmentation faults, memory overflows) to cryptographic bugs, such as ciphertext malleability in KEMs claiming IND-CCA security. We also observe various features of KEMs and DSSs that do not contradict any security guarantees but could appear counter-intuitive. Finally, we compare this methodology with a traditional fuzzing campaign against LibOQS and SUPERCOP, observing that traditional fuzzing harnesses appear less effective in surfacing software and logical bugs
SPHGen: A Program Generator for Fast Polynomial Hash Functions
No full textUniversal hash functions are a widely-used, fundamental building block in constructing more complex cryptographic schemes. This makes achieving high efficiency, both at the design and implementation level, an utmost priority. Using simple polynomial hash functions over prime fields is a popular choice; Poly1305 is a particular instance of such an approach that is standardized and widely deployed. However, even for simple polynomial hash functions, there are significant challenges in designing fast implementations. Firstly, there is a large set of choices for algorithmic parameters such as finite field and limb sizes. Secondly, the complexity and diversity of modern vector instruction set architectures (ISAs) makes performance evaluation, and subsequent parameter selection difficult. In this paper we present SPHGen, a program generator for simple polynomial hash functions. SPHGen takes as input the field parameters and outputs highly optimized code for a given vector ISA. The generated code is automatically verified by means of symbolic execution, ensuring functional correctness. Accompanying SPHGen is an accurate model that predicts the runtime of each generated program. Using SPHGen, one can readily identify the Pareto front of Pareto-optimal hash function parameters w.r.t. the security-performance trade-offs, and, when using the model, even without running any code. SPHGen and the model can be retargeted to different vector ISAs and languages; we consider AVX2, AVX512, AVX512_IFMA, and Jasmin as examples. We generate Jasmin code to ensure memory safety and constant-time execution. We report benchmarks showing that SPHGen offers significant performance improvements over the best previous non-vectorized code. In addition, for large messages, our automatically generated code offers speedups of up to 37% compared to the highly-optimized implementation of Poly1305 in OpenSSL, which is hand-coded in assembly
SoK: Efficient Design and Implementation of Polynomial Hash Functions over Prime Fields
No full textPoly1305 is a widely-deployed polynomial hash function. The rationale behind its design was laid out in a series of papers by Bernstein, the last of which dates back to 2005. As computer architectures evolved, some of its design features became less relevant, but implementers found new ways of exploiting these features to boost its performance. However, would we still converge to this same design if we started afresh with today\u27s computer architectures and applications? To answer this question, we gather and systematize a body of knowledge concerning polynomial hash design and implementation that is spread across research papers, cryptographic libraries, and developers\u27 blogs. We develop a framework to automate the validation and benchmarking of the ideas that we collect. This approach leads us to five new candidate designs for polynomial hash functions. Using our framework, we generate and evaluate different implementations and optimization strategies for each candidate. We obtain substantial improvements over Poly1305 in terms of security and performance. Besides laying out the rationale behind our new designs, our paper serves as a reference for efficiently implementing polynomial hash functions, including Poly1305
The formation of a European identity through a transnational public sphere? The case of three Western European cultural journals, 1989-2006
No full textThis thesis analyses processes of discursive European identity formation in three cultural journals: Esprit, from France, the British New Left Review and the German Merkur during the time periods 1989-92, and, a decade later, during 2003-06.
The theoretical framework which the thesis brings to bear on this analysis is that of the European Public Sphere. This model builds on Jürgen Habermas’s original model of a “public sphere”, and alleges that a sphere of common debate about issues of European concern can lead to a more defined and integrated sense of a European identity which is widely perceived as vague and inchoate. The relevancy of the public sphere model and its connection to the larger debate about European identity, especially since 1989, are discussed in the first part of the thesis.
The second part provides a comparative analysis of the main European debates in the journals during the respective time periods. It outlines the mechanisms by which identity is expressed and assesses when, and to what extent, shared notions of European identity emerge. The analysis finds that identity formation does not occur through a developmental, gradual convergence of views as the European public sphere model envisages. Rather, it is brought about in much more haphazard back-and-forth movements. Moreover, shared notions of European identity between all the journals only arise in moments of perceived crises. Such crises are identified as the most salient factor which galvanizes expressions of a common, shared sense of European identity across national boundaries and ideological cleavages.
The thesis concludes that the model of the EPS is too dependent on a partial view of how identity formation occurs and should thus adopt a more nuanced understanding about the complex factors that are at play in these processes. For the principled attempt to circumscribe identity formation as the outcome of communicative processes alone is likely to be thwarted by external events
SoK: Efficient Design and Implementation of Polynomial Hash Functions over Prime Fields
No full textPoly1305 is a widely-deployed polynomial hash function. The rationale behind its design was laid out in a series of papers by Bernstein, the last of which dates back to 2005. As computer architectures evolved, some of its design features became less relevant, but implementers found new ways of exploiting these features to boost its performance. However, would we still converge to this same design if we started afresh with today’s computer architectures and applications? To answer this question, we gather and systematize a body of knowledge concerning polynomial hash design and implementation that is spread across research papers, cryptographic libraries, and developers’ blogs. We develop a framework to automate the validation and benchmarking of the ideas that we collect. This approach leads us to five new candidate designs for polynomial hash functions. Using our framework, we generate and evaluate different implementations and optimization strategies for each candidate. We obtain substantial improvements over Poly1305 in terms of security and performance. Besides laying out the rationale behind our new designs, our paper serves as a reference for efficiently implementing polynomial hash functions, including Poly1305
Supply chain management of blood products: a literature review.
No full textThis paper presents a review of the literature on inventory and supply chain management of blood products. First, we identify different perspectives on approaches to classifying the existing material. Each perspective is presented as a table in which the classification is displayed. The classification choices are exemplified through the citation of key references or by expounding the features of the perspective. The main contribution of this review is to facilitate the tracing of published work in relevant fields of interest, as well as identifying trends and indicating which areas should be subject to future research.OR in health services; Supply chain management; Inventory; Blood products; Literature review;
Classic McEliece: conservative code-based cryptography: Round 4 Submission
No full textRound 4 submission to the NIST call for postquantum cryptographic primitive
