1,478 research outputs found
Security of Eduroam Passwords
Tartu Ălikool on otsustanud, et Ăźlikooli traadita Ăźhenduse kasutajanimi ja parool peab Ăźhtima Ăźlikooli kontos kasutusel oleva kasutajanime ja parooliga. See tähendab, et juhul kui Ăźlikooli eduroam vĂľrgul leidub mĂľni nĂľrkus, on seda potentsiaalselt vĂľimalik ära kasutada kasutajate Ăźlikooli kontole ligipääsuks. Antud uurimistÜÜ on avastanud Ăźhe sellise nĂľrkuse, milles luuakse vĂľltsitud traadita Ăźhenduse pääsupunkt, et saada kätte kasutaja autentimiseks kasutatava protokolli kasutajapoolset vastust. Selle vastuse pĂľhjal on rĂźndajal vĂľimalik kätte saada kasutaja parooli räsi, mida on omakorda vĂľimalik kasutada Tartu Ălikooli Samba serveriga autentimiseks. Antud uurimistÜÜ sisaldab eduroami ning rĂźnnakus vaja minevate protokollide kirjeldusi ning ettepanekuid, kuidas Tartu Ălikooli eduroami turvalisemaks muuta.The University of Tartu has decided that the university's eduroam accounts will share the same user credentials as the rest of the university's services. This could potentially be abused by exploiting weaknesses in wireless security in order to gain access to a user's university account. The aim of this research was to uncover any such weaknesses. In the course of the research, an attack was discovered, which uses a spoofed access point to capture a handshake between the user and the authenticator, which can be used to retrieve a hash of the user's password. That hash is then used to authenticate to the university's Samba server. The thesis also provides the reader with details on how eduroam and the protocols used in the attack work, and discusses potential improvements to strengthen the security of Tartu University's eduroam
Post-Quantum Secure Time-Stamping
Krßptograafilisi ajatempliprotokolle kasutatakse tþestusena, et ßks dokument eksisteeris enne teist. Postkvantkrßptograafiliselt turvalised ajatempliprotokollid uurivad, kas neid tþestusi on vþimalik vþltsida kasutades kvantarvuteid. Tegu on suuresti uurimata alaga, kuna vþtmeta ajatempliprotokollides kasutatavates primitiivides pole seni leitud kvantarvutite kontekstis tþsiseid nþrkusi. Selles tÜÜs me defineerime, mis on post-kvant turvalised ajatempliprotokollid ning uurime kuidas klassikalised tulemused muutuvad uues raamistikus. Suur erinevus kvantvastaste puhul on see, et meil ei ole vþimalik saada suvalise kvantalgoritmi mitut erinevat käivitust. Tänapäeval teadaolevad tagasipÜÜramise vþtted vþimaldavad kvantalgoritmi tagasi pÜÜrata ainult väga kindlatel tingimustel. Me uurime nende vþtete kombineerimise vþimalikkust ßhe teoreemi tþestamiseks. Sellele teoreemile ei ole hetkel post-kvant standardmudelis ßhtegi tþestust. Me pakume tþestuseta ßhe tagasipÜÜramise konstruktsiooni, mille abil vþib osutuda teoreemi tþestamine vþimalikuks. Me lisaks pakume välja ka minimaalse lahendamata probleemi, mis on esimene samm teoreemi formaalse tþestamiseni.Cryptographic timestamps are used as proof that a certain document existed before another. Post-quantum secure time-stamping examines whether these proofs can be forged using a quantum computer. The field is very unexplored as the primitives used in keyless time-stamping have not shown any serious weakness towards quantum computers. Until now no effort had been made towards formally defining post-quantum secure time-stamping. In this work, we define the notion of post-quantum time-stamping and examine how contemporary classical results change in this new framework. A key difference in the post-quantum setting is that we cannot retrieve multiple separate executions of an arbitrary quantum adversary. Currently known rewinding techniques allow an adversary to be ran again only under very specific conditions. We examine the possibility of combining existing rewinding techniques to prove a theorem for which there is currently no proof in the standard post-quantum model. We conjecture a rewinding construction which could possibly prove the theorem and establish a minimal open problem for formally proving the theorem
Object detection for collision avoidance from lidar point clouds
This thesis advances deep learning models that are essential for collision avoidance of autonomous vehicles. The first contribution is an advanced multi-component loss function for 3D object detection algorithms where location of the object and dimensions of its bounding box are estimated simultaneously. The loss function penalises modelâs training process when the prediction does not match an expected ground truth. The proposed multi-component loss function enables to observe the progress of locating objects and place greater penalty on bounding box estimation when the object is well located and vice versa. This speeds up the training process as it helps the model to solve the easier task of locating the model first before solving the difficult problem of estimating its bounding box dimensions. Second, a novel sequential point cloud processing method for semantic segmentation is proposed. This uses a sequence of point clouds to generate a prediction. However, as point cloud processing is computationally expensive, processing sequences makes it even more computationally expensive. The proposed method alleviates this problem by fusing point cloud data in a latent feature space instead of processing all point clouds in the sequence each time a new prediction is made. As a result, the method takes advantage of sequential processing while keeping the computational overhead low. Finally, a practical unsupervised method to detect potential collisions in unlabelled point clouds is proposed. The method allows to test the performance and efficiency of different deep learning models on novel data without having to annotate the data first. It is based on the observation that most potential collision areas are defined by the closest object of interest (e.g., a car, a person). Also, the method provides a more realistic assessment of collision probability than widely used aggregate metrics
Keeping social distance in a classroom while interacting via a telepresence robot: a pilot study
IntroductionThe use of various telecommunication tools has grown significantly. However, many of these tools (e.g., computer-based teleconferencing) are problematic in relaying non-verbal human communication. Telepresence robots (TPRs) are seen as telecommunication tools that can support non-verbal communication.MethodsIn this paper, we examine the usability of TPRs, and communication distance related behavioral realism in communication situations between physically present persons and a TPR-mediated person. Twenty-four participants, who played out 36 communication situations with TPRs, were observed and interviewed.ResultsThe results indicate that TPR-mediated people, especially women, choose shorter than normal communication distances. The type of the robot did not influence the choice of communication distance. The participants perceived the use of TPRs positively as a feasible telecommunication method.DiscussionWhen introducing TPRs, situations with greater intrapersonal distances require more practice compared to scenarios where a physically present person communicates with a telepresent individual in the audience. In the latter situation, the robot-mediated person could be perceived as âbehaviorally realisticâ much faster than in vice versa communication situations
Genome-wide scan identifies CDH13 as a novel susceptibility locus contributing to blood pressure determination in two European populations
Hypertension is a complex disease that affects a large proportion of adult population. Although approximately half of the inter-individual variance in blood pressure (BP) level is heritable, identification of genes responsible for its regulation has remained challenging. Genome-wide association study (GWAS) is a novel approach to search for genetic variants contributing to complex diseases. We conducted GWAS for three BP traits [systolic and diastolic blood pressure (SBP and DBP); hypertension (HYP)] in the Kooperative Gesundheitsforschung in der Region Augsburg (KORA) S3 cohort (n = 1644) recruited from general population in Southern Germany. GWAS with 395 912 single nucleotide polymorphisms (SNPs) identified an association between BP traits and a common variant rs11646213 (T/A) upstream of the CDH13 gene at 16q23.3. The initial associations with HYP and DBP were confirmed in two other European population-based cohorts: KORA S4 (Germans) and HYPEST (Estonians). The associations between rs11646213 and three BP traits were replicated in combined analyses (dominant model: DBP, P = 5.55 Ă 10â5, effect â1.40 mmHg; SBP, P = 0.007, effect â1.56 mmHg; HYP, P = 5.30 Ă 10â8, OR = 0.67). Carriers of the minor allele A had a decreased risk of hypertension. A non-significant trend for association was also detected with severe family based hypertension in the BRIGHT sample (British). The novel susceptibility locus, CDH13, encodes for an adhesion glycoprotein T-cadherin, a regulator of vascular wall remodeling and angiogenesis. Its function is compatible with the BP biology and may improve the understanding of the pathogenesis of hypertension
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
X-ray emission from the Sombrero galaxy: discrete sources
We present a study of discrete X-ray sources in and around the
bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival
Chandra observations with a total exposure of ~200 ks. With a detection limit
of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30
kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler
et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS
observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray
binaries (LMXBs). We quantify the differential luminosity functions (LFs) for
both the detected GC and field LMXBs, whose power-low indices (~1.1 for the
GC-LF and ~1.6 for field-LF) are consistent with previous studies for
elliptical galaxies. With precise sky positions of the GCs without a detected
X-ray source, we further quantify, through a fluctuation analysis, the GC LF at
fainter luminosities down to 1E35 erg/s. The derived index rules out a
faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent
findings in several elliptical galaxies and the bulge of M31. On the other
hand, the 2-6 keV unresolved emission places a tight constraint on the field
LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101
sources in the halo of Sombrero. The presence of these sources cannot be
interpreted as galactic LMXBs whose spatial distribution empirically follows
the starlight. Their number is also higher than the expected number of cosmic
AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray
surveys. We suggest that either the cosmic X-ray background is unusually high
in the direction of Sombrero, or a distinct population of X-ray sources is
present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres
Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
The azimuthal anisotropy of charged particles in PbPb collisions at
nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS
detector at the LHC over an extended transverse momentum (pt) range up to
approximately 60 GeV. The data cover both the low-pt region associated with
hydrodynamic flow phenomena and the high-pt region where the anisotropies may
reflect the path-length dependence of parton energy loss in the created medium.
The anisotropy parameter (v2) of the particles is extracted by correlating
charged tracks with respect to the event-plane reconstructed by using the
energy deposited in forward-angle calorimeters. For the six bins of collision
centrality studied, spanning the range of 0-60% most-central events, the
observed v2 values are found to first increase with pt, reaching a maximum
around pt = 3 GeV, and then to gradually decrease to almost zero, with the
decline persisting up to at least pt = 40 GeV over the full centrality range
measured.Comment: Replaced with published version. Added journal reference and DO
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