PALPAS - PAsswordLess PAssword Synchronization

Tools that synchronize passwords over several user devices typically store the encrypted passwords in a central online database. For encryption, a low-entropy, password-based key is used. Such a database may be subject to unauthorized access which can lead to the disclosure of all passwords by an offline brute-force attack. In this paper, we present PALPAS, a secure and user-friendly tool that synchronizes passwords between user devices without storing information about them centrally. The idea of PALPAS is to generate a password from a high entropy secret shared by all devices and a random salt value for each service. Only the salt values are stored on a server but not the secret. The salt enables the user devices to generate the same password but is statistically independent of the password. In order for PALPAS to generate passwords according to different password policies, we also present a mechanism that automatically retrieves and processes the password requirements of services. PALPAS users need to only memorize a single password and the setup of PALPAS on a further device demands only a one-time transfer of few static data.Comment: An extended abstract of this work appears in the proceedings of ARES 201

Head descent, moulding and other intrapartum clinical findings in the prediction of cephalopelvic disproportion

ABSTRACT Cephalopelvic disproportion (CPD) is a common and serious obstetric condition, especially in sub-Saharan Africa. Recognition relies on clinical observations, such as cervical dilatation, head descent, moulding, and size of fetus, all made in a trial of labour. No prospective studies have investigated intrapartum clinical observations and their predictive value for CPD. The objectives of this research were 1) to determine the association of intrapartum clinical findings, especially level of head and moulding, with the outcome of CPD, 2) to determine inter-observer agreement of these findings between clinicians, and 3) to compare intrapartum clinical palpation with symphysis-fundal height (SFH) measurement in the prediction of birth weight. A prospective cross-sectional comparative study was done in the Chris Hani Baragwanath labour ward, a large referral centre. The subjects were women at term, in the active phase of labour, with vertex presentations. The author, blinded to previous clinical or ultrasound findings, performed clinical assessments at the same time as the women’s attending clinicians. His observations were not divulged to the clinicians and he did not participate in obstetric management of the women. The primary outcome measures were CPD, defined as caesarean section for poor progress, and birth weight. Five hundred and eight women were examined, of whom 113 (22.2%) had CPD. Multivariate analysis identified short maternal stature, increased SFH, lesser cervical dilatation, long duration of labour, high degree of parieto-parietal moulding, and high degree of caput succedaneum as independent predictors for CPD. Fetal position and occipito-parietal moulding were not predictive, and level of head, by fifths and by station, was poorly predictive. Inter-observer agreement between the author and attending clinicians was moderate for cervical dilatation, engagement of the head in fifths, and caput succedaneum, and poor for engagement of the head by station. SFH measurement was a slightly better predictor of birth weight than clinical fetal weight estimation. The clinical observations that were shown to be predictive for CPD may be useful adjuncts in the management of a trial of labour. Inter-observer agreement of these findings is at best moderate. Measurement of SFH deserves more attention as an intrapartum predictor of birth weight

A quantum algorithm for computing the unit group of an arbitrary degree number field

Computing the group of units in a field of algebraic numbers is one of the central tasks of computational algebraic number theory. It is believed to be hard classically, which is of interest for cryptography. In the quantum setting, efficient algorithms were previously known for fields of constant degree. We give a quantum algorithm that is polynomial in the degree of the field and the logarithm of its discriminant. This is achieved by combining three new results. The first is a classical algorithm for computing a basis for certain ideal lattices with doubly exponentially large generators. The second shows that a Gaussian-weighted superposition of lattice points, with an appropriate encoding, can be used to provide a unique representation of a real-valued lattice. The third is an extension of the hidden subgroup problem to continuous groups and a quantum algorithm for solving the HSP over the group ℝ^n

MoPS: A Modular Protection Scheme for Long-Term Storage

Current trends in technology, such as cloud computing, allow outsourcing the storage, backup, and archiving of data. This provides efficiency and flexibility, but also poses new risks for data security. It in particular became crucial to develop protection schemes that ensure security even in the long-term, i.e. beyond the lifetime of keys, certificates, and cryptographic primitives. However, all current solutions fail to provide optimal performance for different application scenarios. Thus, in this work, we present MoPS, a modular protection scheme to ensure authenticity and integrity for data stored over long periods of time. MoPS does not come with any requirements regarding the storage architecture and can therefore be used together with existing archiving or storage systems. It supports a set of techniques which can be plugged together, combined, and migrated in order to create customized solutions that fulfill the requirements of different application scenarios in the best possible way. As a proof of concept we implemented MoPS and provide performance measurements. Furthermore, our implementation provides additional features, such as guidance for non-expert users and export functionalities for external verifiers.Comment: Original Publication (in the same form): ASIACCS 201

Density of Ideal Lattices

The security of many emph{efficient} cryptographic constructions, e.g.~collision-resistant hash functions, digital signatures, and identification schemes, has been proven assuming the hardness of emph{worst-case} computational problems in ideal lattices. These lattices correspond to ideals in the ring of integers of some fixed number field $K$. In this paper we show that the density of $n$-dimensional ideal lattices with determinant $le b$ among all lattices under the same bound is in $O(b^{1-n})$. So for lattices of dimension $> 1$ with bounded determinant, the subclass of ideal lattices is always vanishingly small

Vagus Nerve Stimulation and External Defibrillation during Resuscitation; a Letter to Editor

Dear Editor;External defibrillation in patients with implanted neuromodulatory devices is a crucial therapeutic challenge. We report a 63-year-old male patient with refractory epilepsy (RE) after recurrent ischaemic strokes in the middle cerebral artery and in the anterior cerebral artery territory 26 and 23 years ago. He received various therapeutic interventions to achieve seizure control with insufficient success. Therefore, vagus nerve stimulation (VNS) (model Pulse 102, Aspire SR, Cyberonics Inc, Houston, Texas) was applied via insertion of a pulse generator in the left upper chest in 2011. VNS stimulation settings were: output current 1.0 mA, pulse width 500 µs, frequency 30 Hz, 30s ON, 3.0 minute OFF.A reduction of seizure frequency was achieved. Last antiepileptic therapy consisted of levetiracetam 1500 mg td, valproate 1000 mg td, and eslicarbazepine 800 mg td.In 2016, he was admitted because of generalized seizure and aspiration pneumonia.  During hospital stay he suffered a cardiac arrest (CA) with pulseless ventricular tachycardia (VT) caused by fulminant pulmonary artery embolism. After successful resuscitation, the patient experienced return of spontaneous circulation (ROSC). During resuscitation, biphasic electric shocks were applied using 150 Joule and subsequently 360 Joule with patches placed approximately 10 cm parasternal and at the left chest below the VNS. After successful ROSC the VNS was checked again and no malfunction could be detected. Stimulation settings were not changed. Impedance was normal. Seizures were not observed during the remaining day. Unfortunately, the patient died within one day after successful resuscitation and ROSC because of therapy refractory circulatory insufficiency.VNS is an established therapeutic approach in treatment of TRE in children and adults to achieve reduction of seizure frequency with proven safety and efficacy. The safety of VNS in emergency situations like cardiac arrest due to VF with need of external defibrillation and application of large amounts of electrical energy is not clear. External defibrillation in VNS patients may potentially be harmful. The literature concerning external defibrillation during resuscitation or external cardioversion (EC) in patients with implanted electronic devices in neurological disorders is sparse. In patients with cardiac pacemakers external defibrillation may damage the cardiac device. EC applied to deep brain stimulation (DBS) patients may cause thalamotomy or DBS failure. Application of electroconvulsive therapy in psychiatric disorders seems to be safe. Two cases of electroconvulsive therapy (ECT) in VNS have been reported by Sharma et al. The first patient was a 66-year old female with major depression and the second one, a 57-year-old male with a history of bipolar disorder. Both had VNS for therapy refractory psychiatric illness. ECT was applied because of further worsening of the mental state without malfunction of the VNS device. To our knowledge, this is the first case of external defibrillation in a patient with VNS for TRE without alteration of the neurostimulator’s function. External defibrillation applied to VNS patients seem to be safe and effective. Several steps should be taken to minimize the electrical current flowing through the neurostimulator. First, position the patches as far away as possible from the VNS at least 10 cm each. Second, position the patches perpendicular to the VNS; use the lowest clinically appropriate output setting, and, finally, confirm that the VNS is functioning properly after defibrillation

LiDIA : a library for computational number theory

In this paper we describe LiDIA, a new library for computational number theory. Why do we work on a new library for computational number theory when such powerful tools as Pari [1], Kant [11], Simath [10] already exist? In fact, those systems are very useful for solving problems for which there exist efficient system routines. For example, using Pari or Kant it is possible to compute invariants of algebraic number fields and Simath can be used to find the rank of an elliptic curve over Q. However, building complicated and efficient software on top of existing systems has in our experience turned out to be very difficult. Therefore, the software of our research group is developed independently of other computer algebra systems

Some remarks concerning the complexity of computing class groups of quadratic fields

AbstractLet O be an order of any quadratic number field. In this paper we show that under the assumption of the generalized Riemann hypothesis the following decision problems are in NP ⊃ co-NP: 1.1. Is a given ideal A of O principal?2.2. Given ideals A1, … , Aκ of O, do their equivalence classes generate the class group of O?3.3. Given ideals A1, … , Aκ of O, is the class group of O the direct product of the cyclic subgroups generated by the equivalence classes of the A1

Finance 1978-79

IPEDS Finance annual report contains the following information: • Revenues by source (e.g., tuition and fees, government, private gifts) • Expenses by function (e.g., instruction, research, plant maintenance and operation) • Scholarships, physical plant assets and indebtedness • Assets, liabilities and net assets • Different formats are used based on the institution’s accounting standard