Perfectly secure steganography: hiding information in the quantum noise of a photograph

We show that the quantum nature of light can be used to hide a secret message within a photograph. Using this physical principle we achieve information-theoretic secure steganography, which had remained elusive until now. The protocol is such that the digital picture in which the secret message is embedded is perfectly undistinguishable from an ordinary photograph. This implies that, on a fundamental level, it is impossible to discriminate a private communication from an exchange of photographs.Comment: 5 pages, 3 figures + appendix : 5 pages, 6 figure

Long-Term Confidential Secret Sharing-Based Distributed Storage Systems

Secret sharing-based distributed storage systems can provide long-term protection of confidentiality and integrity of stored data. This is achieved by periodically refreshing the stored shares and by checking the validity of the generated shares through additional audit data. However, in most real-life environments (e.g. companies), this type of solution is not optimal for three main reasons. Firstly, the access rules of state of the art secret sharing-based distributed storage systems do not match the hierarchical organization in place in these environments. Secondly, data owners are not supported in selecting the most suitable storage servers while first setting up the system nor in maintaining it secure in the long term. Thirdly, state of the art approaches require computationally demanding and unpractical and expensive building blocks that do not scale well. In this thesis, we mitigate the above mentioned issues and contribute to the transition from theory to more practical secret sharing-based long-term secure distributed storage systems. Firstly, we show that distributed storage systems can be based on hierarchical secret sharing schemes by providing efficient and secure algorithms, whose access rules can be adapted to the hierarchical organization of a company and its future modifications. Secondly, we introduce a decision support system that helps data owners to set up and maintain a distributed storage system. More precisely, on the one hand, we support data owners in selecting the storage servers making up the distributed storage system. We do this by providing them with scores that reflect their actual performances, here used in a broad sense and not tied to a specific metric. These are the output of a novel performance scoring mechanism based on the behavioral model of rational agents as opposed to the classical good/bad model. On the other hand, we support data owners in choosing the right secret sharing scheme parameters given the performance figures of the storage servers and guide them in updating them accordingly with the updated performance figures so as to maintain the system secure in the long term. Thirdly, we introduce efficient and affordable distributed storage systems based on a trusted execution environment that correctly outsources the data and periodically computes valid shares. This way, less information-theoretically secure channels have to be established for confidentiality guarantees and more efficient primitives are used for the integrity safeguard of the data. We present a third-party privacy-preserving mechanism that protects the integrity of data by checking the validity of the shares

Hierarchical and dynamic threshold Paillier cryptosystem without trusted dealer

We propose the first hierarchical and dynamic threshold Paillier cryptosystem without trusted dealer and prove its security in the malicious adversary model. The new cryptosystem is fully distributed, i. e., public and private key generation is performed without a trusted dealer. The private key is shared with a hierarchical and dynamic secret sharing scheme over the integers. In such a scheme not only the amount of shareholders, but also their levels in the hierarchy decide whether or not they can reconstruct the secret and new shareholders can be added or removed without reconstruction of the secret

Performing Computations on Hierarchically Shared Secrets

Hierarchical secret sharing schemes distribute a message to a set of shareholders with different reconstruction capabilities. In distributed storage systems, this is an important property because it allows to grant more reconstruction capability to better performing storage servers and vice versa. In particular, Tassa\u27s conjunctive and disjunctive hierarchical secret sharing schemes are based on Birkhoff interpolation and perform equally well as Shamir\u27s threshold secret sharing scheme. Thus, they are promising candidates for distributed storage systems. A key requirement is the possibility to perform function evaluations over shared data. However, practical algorithms supporting this have not been provided yet with respect to hierarchical secret sharing schemes. Aiming at closing this gap, in this work, we show how additions and multiplications of shares can be practically computed using Tassa\u27s conjunctive and disjunctive hierarchical secret sharing schemes. Furthermore, we provide auditing procedures for operations on messages shared hierarchically, which allow to verify that functions on the shares have been performed correctly. We close this work with an evaluation of the correctness, security, and efficiency of the protocols we propose

INTERNACIONALIZAÇÃO DAS UNIVERSIDADES: ESTUDO SOBRE A PRODUÇÃO CIENTÍFICA

A temática internacionalização da educação está cada vez mais presente na realidade das instituições de ensino superior. Essa prática visa, além de promover a diversidade, possibilitar integrar seu corpo acadêmico à comunidade científica global, favorecendo, assim, a instalação de processos de inovação, competitividade e inserção internacional no país. Neste contexto, o estudo tem como objetivo compreender as características da produção científica internacional referente as temáticas internacionalização e universidade. Para isso, foi desenvolvida uma pesquisa bibliométrica, de natureza descritiva e abordagem quantitativa, utilizando como período de análise os anos de 1989 a 2018. Como principais resultados, destaca-se o crescimento do número de artigos publicados ao longo dos anos, apresentando maior quantidade no ano de 2017. China, Estados Unidos e Inglaterra, respectivamente, apresentam maior número de publicações. Ainda, identificou-se que research, students, development, globalization, science, markets, culture e intercultural experience são possíveis hot topics relacionados à internacionalização e universidade. Palavras-chave: Internacionalização. Universidades. Bibliometria.ABSTRACTThe internationalization theme of education is increasingly present in the reality of higher education institutions. This practice aims, besides promoting diversity, to make it possible to integrate its academic body with the global scientific community, thus favoring the installation of innovation, competitiveness and international insertion processes in the country. In this context, the study aims to understand the characteristics of international scientific production regarding the internationalization and university themes. For this, a descriptive bibliometric research and quantitative approach was developed, using as the analysis period the years 1989 to 2018. As main results, we highlight the growth in the number of articles published over the years, presenting a larger amount. in 2017. China, the United States and England, respectively, have the largest number of publications. Moreover, it was identified that research, students, development, globalization, science, markets, culture and intercultural experience are possible hot topics related to internationalization and university.Keywords: Internationalization. Universities. Bibliometrics

Knowledge of gestational alcohol drinking risks: results from a survey among Italian secondary school students

Introduction. Ethanol is the most widely used drug worldwide. Its consumption has been increasing, and it is reported even during childbearing. Prenatal exposure to ethanol can lead to irreversible damages of the fetus. Knowledge about this risk could prevent these damages. There is no information about knowledge of the Italian students on this issue. Methods. Therefore the aim of this study was to describe the awareness of the Italian students attending the last year of secondary school about risk of gestational alcohol drinking for the delivering mother and the fetus. An online multiple-choice anonymous survey for students was used and e-mailed to the all Italian secondary schools. Results. The respondents were 9.921 and the obtained results evidenced that that young females are more informed than males, and students in Northern and Central Italy are better informed than those in the South, especially on general aspects. The most of respondents knows that alcohol consumption during pregnancy can damage the fetus. However, many youngsters failed to translate this belief into the practice. Conclusions. In conclusion, interventions are needed to enhance knowledge and prevent these damages, and health professionals, with nurses in the first row are entitled to provide education on this topic

Impact of different chemotherapy regimens on intestinal mucosal injury assessed with bedside ultrasound: a study in 213 AML patients

IntroductionNeutropenic enterocolitis (NEC) is a life-threatening complication reported in patients with acute myeloid leukemia (AML) following chemotherapy (CHT). Intensive induction and consolidation CHT may damage intestinal mucosa leading to a NEC episode (NECe). NEC reported mortality may be up to 30-60%. Early US-guided bed-side diagnosis and prompt treatment may substantially improve the survival. An emerging worldwide concern is the intestinal colonization by multi-drug-resistant bacteria especially when patients are exposed to chemotherapy regimens potentially correlated to mucosal damage. MethodsIn our study we prospectively enrolled all AML patients admitted in our leukemia unit to receive intensive induction and consolidation chemotherapy and experiencing chemotherapy-induced-neutropenia (CHTN). Results and discussionOverall, we enrolled N=213 patients from 2007 to March 2023. We recorded N=465 CHTN, and N=42 NECe (9.0% incidence). The aim of our study was to assess which chemotherapy regimens are more associated with NEC. We found that ALM1310, followed by 7 + 3 (daunorubicin), 7 + 3 (idarubicin), 5 + 3 + 3 (cytarabine, etoposide, idarubicin), and AML1310 (consolidation) were associated with a statistically higher incidence of NEC. We did not detect NEC episodes in patients treated with CPX-351, 5 + 2 (cytarabine, idarubicine), and high-dose cytarabine. Thus, we found that cytarabine could determine mucosal damage when associated with an anthracycline but not if delivered either alone or as dual-drug liposomal encapsulation of daunorubicin/cytarabine. We also describe NEC mortality, symptoms at diagnosis, intestinal sites involvement, and prognostic significance of bowel wall thickening

Expansion cone for the 3-inch PMTs of the KM3NeT optical modules

[EN] Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45 degrees with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.This work is supported through the EU, FP6 Contract no. 011937, FP7 grant agreement no. 212252, and the Dutch Ministry of Education, Culture and Science.Adrián Martínez, S.; Ageron, M.; Aguilar, JA.; Aharonian, F.; Aiello, S.; Albert, A.; Alexandri, M.... (2013). Expansion cone for the 3-inch PMTs of the KM3NeT optical modules. Journal of Instrumentation. 8(3):1-19. https://doi.org/10.1088/1748-0221/8/03/T03006S1198

Dynamic and Verifiable Hierarchical Secret Sharing

In this work we provide a framework for dynamic secret sharing and present the first dynamic and verifiable hierarchical secret sharing scheme based on Birkhoff interpolation. Since the scheme is dynamic it allows, without reconstructing the message distributed, to add and remove shareholders, to renew shares, and to modify the conditions for accessing the message. Furthermore, each shareholder can verify its share received during these algorithms protecting itself against malicious dealers and shareholders. While these algorithms were already available for classical Lagrange interpolation based secret sharing, corresponding techniques for Birkhoff interpolation based schemes were missing. Note that Birkhoff interpolation is currently the only technique available that allows to construct hierarchical secret sharing schemes that are efficient and allow to provide shares of equal size for all shareholder in the hierarchy. Thus, our scheme is an important contribution to hierarchical secret sharing