1,103 research outputs found
GOTCHA Password Hackers!
We introduce GOTCHAs (Generating panOptic Turing Tests to Tell Computers and
Humans Apart) as a way of preventing automated offline dictionary attacks
against user selected passwords. A GOTCHA is a randomized puzzle generation
protocol, which involves interaction between a computer and a human.
Informally, a GOTCHA should satisfy two key properties: (1) The puzzles are
easy for the human to solve. (2) The puzzles are hard for a computer to solve
even if it has the random bits used by the computer to generate the final
puzzle --- unlike a CAPTCHA. Our main theorem demonstrates that GOTCHAs can be
used to mitigate the threat of offline dictionary attacks against passwords by
ensuring that a password cracker must receive constant feedback from a human
being while mounting an attack. Finally, we provide a candidate construction of
GOTCHAs based on Inkblot images. Our construction relies on the usability
assumption that users can recognize the phrases that they originally used to
describe each Inkblot image --- a much weaker usability assumption than
previous password systems based on Inkblots which required users to recall
their phrase exactly. We conduct a user study to evaluate the usability of our
GOTCHA construction. We also generate a GOTCHA challenge where we encourage
artificial intelligence and security researchers to try to crack several
passwords protected with our scheme.Comment: 2013 ACM Workshop on Artificial Intelligence and Security (AISec
Presenting in Virtual Worlds: Towards an Architecture for a 3D Presenter explaining 2D-Presented Information
Entertainment, education and training are changing because of multi-party interaction technology. In the past we have seen the introduction of embodied agents and robots that take the role of a museum guide, a news presenter, a teacher, a receptionist, or someone who is trying to sell you insurances, houses or tickets. In all these cases the embodied agent needs to explain and describe. In this paper we contribute the design of a 3D virtual presenter that uses different output channels to present and explain. Speech and animation (posture, pointing and involuntary movements) are among these channels. The behavior is scripted and synchronized with the display of a 2D presentation with associated text and regions that can be pointed at (sheets, drawings, and paintings). In this paper the emphasis is on the interaction between 3D presenter and the 2D presentation
Johnny\u27s in the Basement/Mixing up His Medicine: Therapeutic Jurisprudence and Clinical Teaching
Clinical legal education is both more exhilarating and more stressful than traditional legal education. It forces students to confront their pre-existing assumptions about the practice of law and the representation of clients (frequently, indigent and marginalized individuals), and it similarly forces them to integrate new doctrine, theory, and practice in a very different way than regular law classes demand.
Therapeutic jurisprudence considers the role of the law as a therapeutic agent, and examines all aspects of the legal system in an effort to determine whether it is operating therapeutically or anti-therapeutically, and suggests that legal decision-makers consider the potential impact that legal judgments may have on individuals\u27 well-being.
Therapeutic jurisprudence has several applications to clinical teaching: It (1) improves the teaching of skills, (2) gives clinical teachers a better understanding of the dynamics of clinical relationships, (3) investigates ethical concerns and the effect on lawyering roles, and (4) invigorates the way teachers and students question accepted legal practice
Prediction of Fungal Proteins Secreted through Non-Classical Pathways
The Microbotryum genus of smut fungi is known to parasitize flowering plants by colonizing the plant host and ultimately replacing pollen with fungal spores, which continues the transmission process with the help of pollinators to disperse spores A hallmark of this genus of fungi is host specialization wherein one fungal species is only capable of infecting one species of plant host However, there are rare generalists that flout this pattern and one of those generalists, Microbotryum intermedium is the subject of this analysis.
The life cycle of Microbotryum intermedium begins when a pollinator transmits spores to an uninfected flower Meiosis and conjugation take place, and are followed by systemic infection of the plant by the fungu
Achieving the Heisenberg limit with Dicke states in noisy quantum metrology
Going beyond the standard quantum limit in noisy quantum metrology is an
important and challenging task. Here we show how Dicke states can be used to
surpass the standard quantum limit and achieve the Heisenberg limit in open
quantum systems. The system we study has qubits symmetrically coupled to a
resonator and our objective is to estimate the coupling between the qubits and
the resonator. The time-dependent quantum Fisher information with respect to
the coupling is studied for this open quantum system where the same decay rates
are assumed on all qubits. We show that when the system is initialized to a
Dicke state with an optimal excitation number one can go beyond the standard
quantum limit and achieve the Heisenberg limit even for finite values of the
decays on the qubit and the resonator, particularly when the qubits and
resonator are strongly coupled. We compare our results against the highly
entangled GHZ state and a completely separable state and show that the GHZ
state performs quite poorly whereas under certain noise conditions the
separable state is able to go beyond the standard quantum limit due to
subsequent interactions with a resonator.Comment: 11 pages, 7 Figures, typos corrected and references adde
Testing Autonomous Robot Control Software Using Procedural Content Generation
We present a novel approach for reducing manual effort when testing autonomous robot control algorithms. We use procedural content generation, as developed for the film and video game industries, to create a diverse range of test situations. We execute these in the Player/Stage robot simulator and automatically rate them for their safety significance using an event-based scoring system. Situations exhibiting dangerous behaviour will score highly, and are thus flagged for the attention of a safety engineer. This process removes the time-consuming tasks of hand-crafting and monitoring situations while testing an autonomous robot control algorithm. We present a case study of the proposed approach – we generated 500 randomised situations, and our prototype tool simulated and rated them. We have analysed the three highest rated situations in depth, and this analysis revealed weaknesses in the smoothed nearness-diagram control algorithm
Composite Polarons in Ferromagnetic Narrow-band Metallic Manganese Oxides
A new mechanism is proposed to explain the colossal magnetoresistance and
related phenomena. Moving electrons accompanied by Jahn-Teller phonon and
spin-wave clouds may form composite polarons in ferromagnetic narrow-band
manganites. The ground-state and finite-temperature properties of such
composite polarons are studied in the present paper. By using a variational
method, it is shown that the energy of the system at zero temperature decreases
with the formation of composite polaron; the energy spectrum and effective mass
of the composite polaron at finite temperature is found to be strongly
renormalized by the temperature and the magnetic field. It is suggested that
the composite polaron contribute significantly to the transport and the
thermodynamic properties in ferromagnetic narrow-band metallic manganese
oxides.Comment: Latex, no figur
An output-sensitive algorithm for the minimization of 2-dimensional String Covers
String covers are a powerful tool for analyzing the quasi-periodicity of
1-dimensional data and find applications in automata theory, computational
biology, coding and the analysis of transactional data. A \emph{cover} of a
string is a string for which every letter of lies within some
occurrence of . String covers have been generalized in many ways, leading to
\emph{k-covers}, \emph{-covers}, \emph{approximate covers} and were
studied in different contexts such as \emph{indeterminate strings}.
In this paper we generalize string covers to the context of 2-dimensional
data, such as images. We show how they can be used for the extraction of
textures from images and identification of primitive cells in lattice data.
This has interesting applications in image compression, procedural terrain
generation and crystallography
- …