129 research outputs found
A new system for securizing documents through their entire life cycle
No full textThe authenticity of a printed document is taken for granted upon the existence of a handwritten signature or some sort of stamp. The most widespread method used to ensure that a printed document is not tampered with is the mere visual inspection of the document to be verified and of a trusted copy. This is a highly inefficient process. Frauds involving paper documents are very easy to be realized and very difficult to be detected. Only in the digital world, thanks to the “digital signature” (i.e., the encrypted hash of the file to be signed), documents are fully protected from the threat of unauthorized alteration. Unfortunately, during their lifetime documents may be repeatedly
printed and scanned, and digital to paper conversions result in loosing the digital signature. Documents are unprotected from the first time they leave the digital world. The major contribution of this thesis is the definition, design and development of a new system for securizing documents through their entire life cycle. Another key contribution is the design of a novel high capacity barcode, denoted as HCC2D code, without which it would have been hard to embed all the information needed for verifying a document within the document itself: HCC2D codes achieve an effective data density of 3,972 bytes=inch2 with a success rate of 90%, while data densities of stateof-art barcodes are under 2; 000 bytes=inch2.
Our system reaches the following goals: to embed all the security information within the paper itself; to be applicable to any type of document; to identity the regions of the document that have been tampered with; to support identity verification of the user presenting the document; to verify the authenticity of the handwritten signature. To the best of our knowledge, there is no existing solution which is able to address all of those critical points simultaneously.
The experimental evaluation of our system gives interesting results. It gets a negligible probability of not detecting a fraudulent manipulation (under 1%) and of gener-ating a false alarm (under 1%). In particular, a malicious manipulation is detected in 99% of cases. As for face recognition and handwritten signature verification (HSV), we get good results, despite storage constraints due to 2D barcodes: precision and recall curves cross at around 90% for face recognition and at around 89% for HSV
Engineering color barcode algorithms for mobile applications
No full textThe wide availability of on-board cameras in mobile devices and the increasing demand for higher capacity have recently sparked many new color barcode designs. Unfortunately, color barcodes are much more prone to errors than black and white barcodes, due to the chromatic distortions introduced in the printing and scanning process. This is a severe limitation: the higher the expected error rate, the more redundancy is needed for error correction (in order to avoid failures in barcode reading), and thus the lower the actual capacity achieved. Motivated by this, we design, engineer and experiment algorithms for decoding color barcodes with high accuracy. Besides tackling the general trade-off between error correction and data density, we address challenges that are specific to mobile scenarios and that make the problem much more complicated in practice. In particular, correcting chromatic distortions for barcode pictures taken from phone cameras appears to be a great challenge, since pictures taken from phone cameras present a very large variation in light conditions. We propose a new barcode decoding algorithm based on graph drawing methods, which is able to run in few seconds even on low-end computer architectures and to achieve nonetheless high accuracy in the recognition phase. The main idea of our algorithm is to perform color classification using force-directed graph drawing methods: barcode elements which are very close in color will attract each other, while elements that are very far will repulse each other. © 2014 Springer International Publishing
Online handwritten signature verification for low-end devices
No full textHandwritten Signature Verification (HSV) systems are widely used to verify the authenticity of a user signature automatically. In offline systems, the handwritten signature (represented as an image) is taken from a scanned document, while in online systems, pen tablets are used to register the signature, characterized by several dynamics (e.g., its position, pressure and velocity). The main contribution of this work is to present a new online HSV system that is designed to run on low-end mobile devices. Towards this end, we report the results of an experimental evaluation of our system on different online handwritten signature datasets with low-end mobile devices
La práctica epistolar, pública y privada, de Giovanni Querini, embajador de la república de Venecia en España (1768-1773)
No full textAnálisis de la práctica epistolar de Giovanni Querini, embajador de la república de Venecia en España durante los años 1768 y 1772. A través del examen de los despachos oficiales enviados a su gobierno y de la correspondencia cruzada con su esposa Caterina Contarini, se describen las contingencias de los correos, la dualidad del discurso epistolar y la eficacia de las cartas privadas para la preservación de la intimidad matrimonial y la sociabilidad familiar desde la distanciaThis article analyses the letter writing of Giovanni Querini, ambas-sador of the Republic of Venice in Spain from 1768 to 1772. Through examination of the official letters sent by him to his government and though the correspondence he maintained with his wife Caterina Contarini, the author describes the contingencies of the post, the duality of these epistolary discourses and the effectiveness of private letters for preserving marital intimacy and family sociability from a distanc
La práctica epistolar, pública y privada, de Giovanni Querini, embajador de la república de Venecia en España (1768-1773)
No full textAnálisis de la práctica epistolar de Giovanni Querini, embajador de la república de Venecia en España durante los años 1768 y 1772. A través del examen de los despachos oficiales enviados a su gobierno y de la correspondencia cruzada con su esposa Caterina Contarini, se describen las contingencias de los correos, la dualidad del discurso epistolar y la eficacia de las cartas privadas para la preservación de la intimidad matrimonial y la sociabilidad familiar desde la distanciaThis article analyses the letter writing of Giovanni Querini, ambas-sador of the Republic of Venice in Spain from 1768 to 1772. Through examination of the official letters sent by him to his government and though the correspondence he maintained with his wife Caterina Contarini, the author describes the contingencies of the post, the duality of these epistolary discourses and the effectiveness of private letters for preserving marital intimacy and family sociability from a distanc
The Public and Private Epistolary Practice of Giovanni Querini, Ambassador of the Venetian Republic in Spain (1768-1773)
No full textThis article analyses the letter writing of Giovanni Querini, ambassador of the Republic of Venice in Spain from 1768 to 1772. Through examination of the official letters sent by him to his government and though the correspondence he maintained with his wife Caterina Contarini, the author describes the contingencies of the post, the duality of these epistolary discourses and the effectiveness of private letters for preserving marital intimacy and family sociability from a distance
Correction to: Can Cytokine Blocking Prevent Depression in COVID-19 Survivors? (Journal of Neuroimmune Pharmacology, (2021), 16, 1, (1-3), 10.1007/s11481-020-09966-z)
No full textThe original version of this article unfortunately contained a mistake. The author name “Mario Mazza” was incorrect
Corso del Rheno : parte settentrio et parte meridionale : dedicato all'illustrissimo et excellentissimo S. Girolamo Querini, procuratore di S. Marco in Venetia, 1690
No full textÉchelle(s) : 1:960 000Appartient à l’ensemble documentaire : BNUStras1Appartient à l’ensemble documentaire : BNUStr00
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