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A Workbench for the BOWS Contest  [cached]
Andreas Westfeld
EURASIP Journal on Information Security , 2008, DOI: 10.1155/2007/64521
Abstract: The first break our watermarking system (BOWS) contest challenged researchers to remove the watermark from three given images. Participants could submit altered versions of the images to an online detector. For a successful attack, the watermark had to be unreadable to this detector with a quality above 30 ¢ € ‰dB peak signal-to-noise ratio. We implemented our experiments in R, a language for statistical computing. This paper presents the BOWS package, an extension for R, along with examples for using this experimental environment. The BOWS package provides an offline detector for several platforms. Furthermore, the particular watermarking algorithm used in the contest is analysed. We show how to find single coefficient attacks and derive high-quality images (62.6 ¢ € ‰dB PSNR) with full knowledge of the key.
A Workbench for the BOWS Contest  [cached]
Westfeld Andreas
EURASIP Journal on Information Security , 2007,
Abstract: The first break our watermarking system (BOWS) contest challenged researchers to remove the watermark from three given images. Participants could submit altered versions of the images to an online detector. For a successful attack, the watermark had to be unreadable to this detector with a quality above 30 dB peak signal-to-noise ratio. We implemented our experiments in R, a language for statistical computing. This paper presents the BOWS package, an extension for R, along with examples for using this experimental environment. The BOWS package provides an offline detector for several platforms. Furthermore, the particular watermarking algorithm used in the contest is analysed. We show how to find single coefficient attacks and derive high-quality images (62.6 dB PSNR) with full knowledge of the key.
Singular Monopoles from Cheshire Bows  [PDF]
Chris D. A. Blair,Sergey A. Cherkis
Mathematics , 2010, DOI: 10.1016/j.nuclphysb.2010.11.014
Abstract: Singular monopoles are nonabelian monopoles with prescribed Dirac-type singularities. All of them are delivered by the Nahm's construction. In practice, however, the effectiveness of the latter is limited to the cases of one or two singularities. We present an alternative construction of singular monopoles formulated in terms of Cheshire bows. To illustrate the advantages of our bow construction we obtain an explicit expression for one U(2) gauge group monopole with any given number of singularities of Dirac type.
Design and Analysis of the First BOWS Contest  [cached]
Piva A,Barni M
EURASIP Journal on Information Security , 2007,
Abstract: The break our watermarking system (BOWS) contest was launched in the framework of the activities carried out by the European Network of Excellence for Cryptology ECRYPT. The aim of the contest was to investigate how and when an image watermarking system can be broken while preserving the highest possible quality of the content, in the case the watermarking system is subject to a massive worldwide attack. The great number of participants and the echo that the contest has had in the watermarking community contributed to make BOWS a great success. From a scientific point of view, many insights into the problems attackers have to face with when operating in a practical scenario have been obtained, confirming the threat posed by the sensitivity attack, which turned out to be the most successful attack. At the same time, several interesting modifications of such an attack have been proposed to make it work in a real scenario under limited communication and time resources. This paper describes how the contest has been designed and analyzes the general progress of the attacks during the contest.
Design and Analysis of the First BOWS Contest  [cached]
A. Piva,M. Barni
EURASIP Journal on Information Security , 2007, DOI: 10.1155/2007/98684
Abstract: The break our watermarking system (BOWS) contest was launched in the framework of the activities carried out by the European Network of Excellence for Cryptology ECRYPT. The aim of the contest was to investigate how and when an image watermarking system can be broken while preserving the highest possible quality of the content, in the case the watermarking system is subject to a massive worldwide attack. The great number of participants and the echo that the contest has had in the watermarking community contributed to make BOWS a great success. From a scientific point of view, many insights into the problems attackers have to face with when operating in a practical scenario have been obtained, confirming the threat posed by the sensitivity attack, which turned out to be the most successful attack. At the same time, several interesting modifications of such an attack have been proposed to make it work in a real scenario under limited communication and time resources. This paper describes how the contest has been designed and analyzes the general progress of the attacks during the contest.
Breaking the BOWS Watermarking System: Key Guessing and Sensitivity Attacks  [cached]
Comesa?a Pedro,Pérez-González Fernando
EURASIP Journal on Information Security , 2007,
Abstract: From December 15, 2005 to June 15, 2006, the watermarking community was challenged to remove the watermark from 3 different 512×512 watermarked images while maximizing the peak signal-to-noise ratio (PSNR) measured by comparing the watermarked signals with their attacked counterparts. This challenge, which bore the inviting name of Break Our Watermarking System (BOWS), had as its main objective to enlarge the current knowledge on attacks to watermarking systems. In this paper, the main results obtained by the authors when attacking the BOWS system are presented and compared with strategies followed by other groups. Essentially, two different approaches have been followed: exhaustive search of the secret key and blind sensitivity attacks.
Breaking the BOWS Watermarking System: Key Guessing and Sensitivity Attacks  [cached]
Pedro Comesa?a,Fernando Pérez-González
EURASIP Journal on Information Security , 2007, DOI: 10.1155/2007/25308
Abstract: From December 15, 2005 to June 15, 2006, the watermarking community was challenged to remove the watermark from 3 different 512 —512 watermarked images while maximizing the peak signal-to-noise ratio (PSNR) measured by comparing the watermarked signals with their attacked counterparts. This challenge, which bore the inviting name of Break Our Watermarking System (BOWS), had as its main objective to enlarge the current knowledge on attacks to watermarking systems. In this paper, the main results obtained by the authors when attacking the BOWS system are presented and compared with strategies followed by other groups. Essentially, two different approaches have been followed: exhaustive search of the secret key and blind sensitivity attacks.
Rela es interpessoais à luz do psicodrama/The interpersonal relations in view of psychodrama
Marinalva Imaculada Cuzin
ETD : Educa??o Temática Digital , 2008,
Abstract: CUZIN, M. I. As rela es interpessoais à luz do psicodrama.389fl.2008. Tese (Doutorado em Educa o) – Faculdade de Educa o, Universidade Estadual de Campinas, Campinas. 2008.
Psychometric evaluation of the Forensic Inpatient Observation Scale (FIOS) in youngsters with a judicial measure  [cached]
van Nieuwenhuizen Chijs,Bongers Ilja L
Child and Adolescent Psychiatry and Mental Health , 2011, DOI: 10.1186/1753-2000-5-30
Abstract: Background In this article, the psychometric properties of the Forensic Inpatient Observation Scale (FIOS) were examined. This instrument was developed to observe behavioral functioning of forensic psychiatric patients. Up till now, it has only been used among adult forensic psychiatric patients and this is the first study in which the FIOS is used with youngsters. Methods Data were gathered of 133 patients. The FIOS was routinely used to assess the psychiatric condition of youngsters at fixed intervals with a three-month time period between each measurement. Ward staff working in close contact with the patient conducted the assessments. Of these 133 patients, an YSR/ASR questionnaire was available for 96 of them and a TRF for 110 of the 133 patients. For the descriptive, reliability and validity analyses, SPSS version 16.0 was used. Factor analyses were performed by means of Mplus Version 5.2. Results A series of confirmatory and exploratory factor analyses revealed a five-factor structure for the FIOS. The five-factor structure consisted of the following scales: self-care, social behavior, oppositional behavior, verbal skills and distress. The insight scale of the original factor structure could not be replicated in the youth sample. Cronbach's alpha's of the five scales ranged from .70 to .85. The self-care, verbal skills and oppositional behavior scales of the FIOS showed no relation with emotional and behavior problems reported by the patients themselves or their teachers. The distress scale of the FIOS did show a relation with the emotional problems reported by patients themselves and the social behavior scale with behavioral problems as reported by teachers. Conclusions The internal consistency of the FIOS was sufficient and the factor structure in the present sample of youngsters was in general comparable to the original factor structure in an adult sample. Its value lies in the focus on behavioral functioning of youngsters with judicial measures. What remains to be seen is whether this instrument is sensitive enough to register all aspects of behavioral changes, whether the interrater reliability is sufficient, and whether it has predictive validity to relapse and recidivism.
A eletrostática na corrente elétrica em fios
Leal Ferreira G. F.,Figueiredo Mariangela T. de
Revista Brasileira de Ensino de Física , 2003,
Abstract: O artigo refere-se à quest o 'Quem cria o campo elétrico que move as cargas na corrente elétrica em fios?'. Através de modelo simples, mostra-se que uma distribui o de cargas, variando linearmente ao longo do fio e depositada na sua superficie, cria campo uniforme no seu interior. O modelo utilizado é o de um cabo coaxial fechado em ambas as extremidades, com potenciais convenientemente escolhidos em suas parades. Com este estudo, torna-se possível ilustrar a importante liga o conceitual entre a Eletrostática e s Eletrodinamica, historicamente t o importante no desenvolvimento do Eletrogenetismo.
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