Public keys quality

Dissertação de mestrado em Matemática e ComputaçãoThe RSA cryptosystem, invented by Ron Rivest, Adi Shamir and Len Adleman ([Rivest et al., 1978]) is the most commonly used cryptosystem for providing privacy and ensuring authenticity of digital data. RSA is usually used in contexts where security of digital data is priority. RSA is used worldwide by web servers and browsers to secure web traffic, to ensure privacy and authenticity of e-mail, to secure remote login sessions and to provide secure electronic creditcard payment systems. Given its importance in the protection of digital data, vulnerabilities of RSA have been analysed by many researchers. The researches made so far led to a number of fascinating attacks. Although the attacks helped to improve the security of this cryptosystem, showing that securely implementing RSA is a nontrivial task, none of them was devastating. This master thesis discusses the RSA cryptosystem and some of its vulnerabilities as well as the description of some attacks, both recent and old, together with the description of the underlying mathematical tools they use. Although many types of attacks exist, in this master thesis only a few examples were analysed. The ultimate attack, based in the batch-GCD algorithm, was implemented and tested in the RSA keys produced by a certificated Hardware Security Modules Luna SA and the results were commented. The random and pseudorandom numbers are fundamental to many cryptographic applications, including the RSA cryptosystems. In fact, the produced keys must be generated in a specific random way. The National Institute of Standards and Technology, responsible entity for specifying safety standards, provides a package named "A Statistical Test Suit for Random and Pseudorandom Number Generators for Cryptography Applications" which was used in this work to test the randomness of the Luna SA generated numbers. All the statistical tests were tested in different bit sizes number and the results commented. The main purpose of this thesis is to study the previous subjects and create an applications capable to test the Luna SA generated numbers randomness, a well as evaluate the security of the RSA. This work was developed in partnership with University of Minho and Multicert.O RSA, criado por Ron Rivest, Adi Shamir e Len Adleman ([Rivest et al., 1978]) é o sistema criptográfico mais utilizado para providenciar segurança e assegurar a autenticação de dados utilizados no mundo digital. O RSA é usualmente usado em contextos onde a segurança é a grande prioridade. Hoje em dia, este sistema criptográfico é utilizado mundialmente por servidores web e por browsers, por forma a assegurar um tráfego seguro através da Internet. É o sistema criptográfico mais utilizado na autenticação de e-mails, nos inícios de sessões remotos, na utilização de pagamentos através de cartões multibanco, garantindo segurança na utilização destes serviços. Dada a importância que este sistema assume na proteção da informação digital, as suas vulnerabilidades têm sido alvo de várias investigações. Estas investigações resultaram em vários ataques ao RSA. Embora nenhum destes ataques seja efetivamente eficaz, todos contribuíram para um aumento da segurança do RSA, uma vez que as implementações de referência deste algoritmo passaram a precaver-se contra os ataques descobertos. Esta tese de mestrado aborda o sistema criptográfico RSA, discutindo algumas das suas vulnerabilidades, assim como alguns ataques efetuados a este sistema, estudando todos os métodos matemáticos por estes usados. Embora existam diversos ataques, apenas alguns serão abordados nesta tese de mestrado. O último ataque, baseado no algoritmo batch-GCD foi implementado e foram feitos testes em chaves RSA produzidas por um Hardware Security Module Luna SA certificado e os resultados obtidos foram discutidos. Os números aleatórios e pseudoaleatórios são fundamentais a todas as aplicações criptográficas, incluindo, portanto, o sistema criptográfico RSA. De facto, as chaves produzidas deverão ser geradas com alguma aleatoriedade intrínseca ao sistema. O Instituto Nacional de Standards e Tecnologia, entidade responsável pela especificação dos standards de segurança, disponibiliza um pacote de testes estatísticos, denominado por "A Statistical Test Suit for Random and Pseudorandom Number Generators for Cryptography Applications". Estes testes estatísticos foram aplicados a números gerados pelo Luna SA e os resultados foram, também, comentados. O objetivo desta tese de mestrado é desenvolver capacidade de compreensão sobre os assuntos descritos anteriormente e criar uma aplicação capaz de testar a aleatoriedade dos números gerados pelo Luna SA, assim como avaliar a segurança do sistema criptográfico RSA. Este foi um trabalho desenvolvido em parceria com a Universidade do Minho e com a Multicert

Characterisation of exudates, growth and performance of brassica rapa lines under controlled environment conditions and the impact of soil microorganisms on the uptake of phosphate by the plant

O fósforo (P) é um nutriente de elevado interesse e procura pelas indústrias agrícolas e um fator limitante nos solos de produções agrícolas como por exemplo Brassica rapa. Porém a presença de P no solo não significa que se encontra disponível para absorção pelas plantas. Para a resolução deste problema, os profissionais recorrem à adição de P nos solos, acabando por levar a problemas de eutrofização, quando este é perdido no meio. As fosfatases excretadas pelas plantas e microrganismos participam numa das reações envolvidas na absorção de P pelas plantas. No caso da indústria agrícola, se não houver uma evolução nos procedimentos aplicados atualmente, com a demanda atual e/ou futura, a escassez de nutrientes nos solos pode tornar-se uma realidade afetando negativamente o sector agrícola. Uma das soluções para contrariar esta corrente é uso de rizobactérias promotoras do crescimento de plantas (PGPR), como Pseudomonas fluorescens, Pseudomonas putida e Flavobacterium johnsoniae. O objetivo deste trabalho laboratorial foi avaliar a excreção enzimática in vitro de ácido e alcalino fosfatases (AcP e AlP) por três diferentes PGPR (P. fluorescens, P. putida e F. johnsoniae) e pela B. rapa subsp. trilocularis line R-o-18 na presença e ausência de P e a diferentes pHs. Para a análise da atividade enzimática dos microrganismos e da planta recorreu-se ao uso da técnica de zimografia. O estudo da atividade enzimática foi realizado ao longo de 21 dias de crescimento da planta, em três solos diferentes, dois com P adicionado, como controlos (+) (John Innes no. 3 e solo arenoso) e um sem adição de P, como controlo (-) (solo de turfa e areia), e em Murashige and Skoog (MS) com P adicionado como controlo (+) e sem P adicionado como controlo (-). Os tempos foram avaliados aos 7, 14 e 21 dias. Os resultados mostraram-se significativamente diferentes aos diferentes pHs, e aos diferentes tempos de crescimento (p < 0.05). Contudo, os três solos com e sem adição de P a pH 6.5 e os meios de MS com e sem P adicionado a pHs 6.5 e 11 apresentam resultados não significativamente diferentes de atividade enzimática. A avaliação feita a B. rapa inoculada com as PGPR crescida nos dois diferentes meios MS, apresentam resultados estatisticamente similares entre si. Em conclusão, pela técnica da zimografia, a análise feita nos primeiros 21 dias de crescimento de B. rapa, a concentrações de P diferentes e com o uso PGPR não afetaram significativamente a secreção enzimática e consequentemente a sua atividade.Phosphorus (P) is a nutrient of high interest and demand for agricultural industries and is a limiting factor in the soils to produce plants such as Brassica rapa. However, the presence of P in the soil does not mean that it is available for absorption by plants. In order to solve this problem, the farmers add more phosphorus to the crops, which if lost from the field can lead to eutrophication problems. One of the reactions involved in the uptake of P by plants is related to the phosphatases excreted by plants and microorganism present in the environment. In the case of the agricultural industry, if there is no evolution in the current procedures used, current and future demands for food will trigger nutrient scarcity in soils, adversely affecting the agricultural sector. One of the solutions to counteract this chain is the use of plant growth promoting rhizobacteria (PGPR), such as Pseudomonas fluorescens, Pseudomonas putida and Flavobacterium johnsoniae. The objective of this work was to evaluate the in vitro enzymatic excretion of acid and alkaline phosphatases (AcP and AlP) by three different PGPRs (P. fluorescens, P. putida and F. johnsoniae) and by B. rapa subsp. trilocularis line R-o-18 in the presence and absence of P and at different pHs. For the analysis of the enzymatic activity of microorganisms and plant, zymography technique was used. The study of the enzymatic activity was performed during 21 days of plant growth in three different soils, two with P added, as (+) controls (John Innes no. 3 and sandy soil) and one without P added, as (-) control (peat and sand soil), and Murashige and Skoog (MS) mediums with P added as (+) control and without P added as (-) control. The times were evaluated at 7, 14 and 21 days. The results were significantly different at different pHs, and at different growth times (p <0.05). However, the three soils with and without addition of P at pH 6.5 and the MS medium with and without P added at pHs 6.5 and 11 presented results non-significantly different of enzymatic activity. The evaluation made to B. rapa inoculated with the PGPR grown in the two different MS mediums presents statistically similar results among themselves. In conclusion, the analysis made with zymography technique, in the first 21 days of growth of B. rapa, at different concentrations of P and with the use of PGPR did not significantly affect the enzymatic secretion and consequently its activity

Relation between functional ankle instability and physiotherapy in ballet dancers

Poster presented at the 2nd International Congress of CiiEM - Translational Research and Innovation in Human and Health Science. 11-13 June, 2017, Campus Egas Moniz, Monte de Caparica, Portugal.N/

Performance of PNAEQ participant’s results for HIV and HCV infection in the First EQA round 2019

The Portuguese National External Quality Assessment Program (PNAEQ) has been collaborating with Labquality since 2002. One of the first schemes distributed to PNAEQ participants was for HIV laboratory tests, followed by HCV laboratory tests scheme in 2003. A suitable scheme for Point of Care Testing (POCT) is available for HIV since 2012 and for HCV since 2018. Given the burden of HIV and HCV diseases, the Portuguese legislation allows, since 2018, that other locations than laboratories, such as pharmacies and Non-Governmental-Organizations (NGOs), perform tests for detect HIV and HCV infection. For this purpose, and in order to assure reliable results that leads to an early correct diagnostic and a timely treatment, leading to a decrease in the person-to-person transmission of HIV and HCV infection, a specific training to perform POCT for HIV and HCV is mandatory for these entities, as well as the participation in such EQA schemes, namely the PNAEQ-Labquality. The performance of PNAEQ participants for HIV and HCV tests in the First EQA round 2019 was considered in general good. For HIV POCT, the user that reported an undetermined result proceeded correctly requesting a second sample for confirmation. Regarding the two incorrect results reported by laboratories, it is necessary to review the internal validation procedure and revalidation of the laboratory test, and implement corrective and preventive actions. The training of participants that used POCT for the first time proved to be effective in acquiring skills to perform the tests properly. PNAEQ will continue to provide education and training in quality control and motivate all the participants to continuously evaluate the results from the internal quality control and the reports from the external quality assessment.N/

Magnetic proximity sensor based on magnetoelectric composites and printed coils

Magnetic sensors are mandatory in a broad range of applications nowadays, being the increasing interest on such sensors mainly driven by the growing demand of materials required by Industry 4.0 and the Internet of Things concept. Optimized power consumption, reliability, flexibility, versatility, lightweight and low-temperature fabrication are some of the technological requirements in which the scientific community is focusing efforts. Aiming to positively respond to those challenges, this work reports magnetic proximity sensors based on magnetoelectric (ME) polyvinylidene fluoride (PVDF)/Metglas composites and an excitation-printed coil. The proposed magnetic proximity sensor shows a maximum resonant ME coefficient (α) of 50.2 Vcm−1 Oe−1, an AC linear response (R2 = 0.997) and a maximum voltage output of 362 mV, which suggests suitability for proximity-sensing applications in the areas of aerospace, automotive, positioning, machine safety, recreation and advertising panels, among others.This research was funded by CT- Fundação para a Ciência e Tecnologia in the framework of the Strategic Funding UID/FIS/04650/2019 and under projects PTDC/EEI-SII/5582/2014, PTDC/BTM-MAT/28237/2017 and PTDC/EMD-EMD/28159/2017. A.C.L. and N.P. acknowledge also support from FCT (SFRH/BD/132624/2017 and SFRH/BD/131729/2017 grants respectively). P. Martins also thanks FCT for the contract under the Stimulus of Scientific Employment, Individual Support—2017 Call (CEECIND/03975/2017). Finally, the authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) and from the Basque Government Industry and Education Department under the ELKARTEK, HAZITEK and PIBA (PIBA-2018-06) programs, respectivel

Infeções sexualmente transmissíveis em jovens

As infeções sexualmente transmissíveis (IST) constituem um problema persistente de saúde pública. Os adolescentes e adultos jovens são os que apresentam as taxas de prevalência mais elevadas para algumas infeções sexualmente transmissíveis. As IST são transmitidas, principalmente, por contacto sexual sem o uso de preservativo.info:eu-repo/semantics/publishedVersio

Vantagens de Participação no Programa Nacional de Avaliação Externa da Qualidade (PNAEQ)

Introdução: O Programa Nacional de Avaliação Externa da Qualidade (PNAEQ) foi implementado no Instituto Nacional de Saúde Doutor Ricardo Jorge, Portugal, em 1978. A participação é voluntária, e permite monitorizar e implementar a melhoria da qualidade analítica, e de um modo independente, garantir a qualidade dos serviços prestados. Objetivo: Apresentação das vantagens que a participação nos programas de Avaliação Externa da Qualidade (AEQ) do PNAEQ, tem para os participantes.N/

Tunning pectinase activity under the effects of electric fields in the enhanced clarification of wine must

Introduction: Pectinolytic enzymes are of great importance for the clarification process of “Vinho Verde” wine must, contributing to the reduction of haze development. During the last decade, a growing body of knowledge has been established about the effects of electric fields on the activation of important food enzymes. However, the influence of electrical parameters on catalytic activity is enzyme-dependent and should be evaluated on a case-by-case basis. This work describes, for the first time, the effects of electric fields and electrical frequency on the activity of pectinase (PEC) in the accelerated clarification of “Vinho Verde” must. Method: Moderate electric fields (MEF) with intensities below 20 V/cm and at electrical frequencies ranging from 50 to 20 kHz were applied at temperatures between 15 and 35°C. Enzymatic activity was measured for 25 min, and the initial rate of reaction was determined by the coefficient of the linear plot of galacturonic acid (GAL) production as a function of time. Results: The results show that electrical frequency can increase enzymatic activity depending on temperature conditions; at 20°C and with electrical frequencies of 2 and 20 kHz, enzymatic activity increased by up to 40 and 20%, respectively, when compared with the control sample (without the application of MEF). Temperature dependence was evaluated through the Arrhenius equation, showing that energy of activation (Ea) can be reduced from 9.2 to 6.6 kJ/mol at sub-optimal temperatures for PEC activity when MEF is applied. Discussion: Electrical parameters, when combined with temperatures below 20°C, reduced pectin concentration in “Vinho Verde” wine must by up to 42% of its initial content. This emergent treatment can be integrated in relevant environmental conditions, presenting an opportunity to increase enzyme efficiency even in low-temperature conditions, which favors the winemaking process.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit, LABBELSAssociate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems, LA/P/0029/2020, and funded by BIOECONORTE (ref. NORTE-01-0145-FEDER-000070) with a funding body from the Norte Portugal Regional Coordination and Development Commission (CCDR-N), NORTE2020, Portugal 2020 and ESIF - European Structural and Investment Funds.info:eu-repo/semantics/publishedVersio

Investigating the role of symptom valorisation in tuberculosis patient delay in urban areas in Portugal

URBANTB group: Patrícia Soares (Representative of the consortium), Mário Carreira, Sofia Pereira, Catarina Alves, Filipe Alves, Ana Rodrigues, Ana Moreira, Márcia Cardoso, Sandra Mota, Ana Gomes, Liliana Ferreira, Marta Lopes, Isabel Correia, Juan Rachadell, Maria Gameiro, Ângela Dias, Manuel Pereira, Jorge Gonçalves, Maria Gonçalves, Adriana Taveira, Celene Neves, Lucinda Silva, Maria Mendes, Maria Teixeira, Maria Pereira, Milena Piedade, Antónia Teixeira & Carlos Carvalho.Background: Diagnosis delay contributes to increased tuberculosis (TB) transmission and morbimortality. TB incidence has been decreasing in Portugal, but median patient delay (PD) has risen. Symptom valorisation may determine PD by influencing help-seeking behaviour. We aimed to analyse the association between symptom valorisation and PD, while characterising individuals who disregarded their symptoms. Methods: A cross-sectional study was conducted among TB patients in Lisbon and Oporto in 2019 - 2021. Subjects who delayed seeking care because they did not value their symptoms or thought these would go away on their own were considered to have disregarded their symptoms. PD was categorised using a 21-day cut-off, and a 30-day cut-off for sensitivity analysis. We estimated the effect of symptom valorisation on PD through a directed acyclic graph. Then, a multivariable regression analysis characterised patients that disregarded their symptoms, adjusting for relevant variables. We fitted Poisson regression models to estimate crude and adjusted prevalence ratios (PR). Results: The study included 75 patients. Median PD was 25 days (IQR 11.5-63.5), and 56.0% of participants had PD exceeding 21 days. Symptom disregard was reported by 38.7% of patients. Patients who did not value their symptoms had higher prevalence of PD exceeding 21 days compared to those who valued their symptoms [PR 1.59 (95% CI 1.05-2.42)]. The sensitivity analysis showed consistent point estimates but wider confidence intervals [PR 1.39 (95% CI 0.77-2.55)]. Being a smoker was a risk factor for symptom disregard [PR 2.35 (95% CI 1.14-4.82)], while living in Oporto [PR 0.35 (95% CI 0.16-0.75)] and having higher household incomes [PR 0.39 (95% CI 0.17-0.94)] were protective factors. Conclusions: These findings emphasise the importance of symptom valorisation in timely TB diagnosis. Patients who did not value their symptoms had longer PD, indicating a need for interventions to improve symptom recognition. Our findings also corroborate the importance of the socioeconomic determinants of health, highlighting tobacco as a risk factor both for TB and for PD.This work was supported by the Fundação para a Ciência e Tecnologia (FCT, Portugal) [Grant: PTDC/SAU-PUB/31346/2017]. The present publication was funded by Fundação para a Ciência e Tecnologia (FCT, Portugal) national support through Comprehensive Health Research Centre (CHRC) [UIDP/04923/2020].info:eu-repo/semantics/publishedVersio