On the hardness of the sum of K mins problem

The sum of k mins protocol was proposed by Hopper and Blum as a protocol for secure human identification. The goal of the protocol is to let an unaided human securely authenticate to a remote server. The main ingredient of the protocol is the sum of k mins problem. The difficulty of solving this problem determines the security of the protocol. In this paper, we show that the sum of k mins problem is NP-Complete and W[1]-Hard. This latter notion relates to fixed parameter intractability. We also discuss the use of the sum of k mins protocol in resource-constrained devices.

Does counting still count? Revisiting the security of counting based user authentication protocols against statistical attacks

At NDSS 2012, Yan et al. analyzed the security of several challenge-response type user authentication protocols against passive observers, and proposed a generic counting based statistical attack to recover the secret of some counting based protocols given a number of observed authentication sessions. Roughly speaking, the attack is based on the fact that secret (pass) objects appear in challenges with a different probability from non-secret (decoy) objects when the responses are taken into account. Although they mentioned that a protocol susceptible to this attack should minimize this difference, they did not give details as to how this can be achieved barring a few suggestions. In this paper, we attempt to fill this gap by generalizing the attack with a much more comprehensive theoretical analysis. Our treatment is more quantitative which enables us to describe a method to theoretically estimate a lower bound on the number of sessions a protocol can be safely used against the attack. Our results include 1) two proposed fixes to make counting protocols practically safe against the attack at the cost of usability, 2) the observation that the attack can be used on non-counting based protocols too as long as challenge generation is contrived, 3) and two main design principles for user authentication protocols which can be considered as extensions of the principles from Yan et al. This detailed theoretical treatment can be used as a guideline during the design of counting based protocols to determine their susceptibility to this attack. The Foxtail protocol, one of the protocols analyzed by Yan et al., is used as a representative to illustrate our theoretical and experimental results.

Cryptanalysis of the convex hull click human identification protocol

Recently a convex hull based human identification protocol was proposed by Sobrado and Birget, whose steps can be performed by humans without additional aid. The main part of the protocol involves the user mentally forming a convex hull of secret icons in a set of graphical icons and then clicking randomly within this convex hull. In this paper we show two efficient probabilistic attacks on this protocol which reveal the user’s secret after the observation of only a handful of authentication sessions. We show that while the first attack can be mitigated through appropriately chosen values of system parameters, the second attack succeeds with a non-negligible probability even with large system parameter values which cross the threshold of usability.

A new human identification protocol and Coppersmith's baby-step giant-step algorithm

We propose a new protocol providing cryptographically secure authentication to unaided humans against passive adversaries. We also propose a new generic passive attack on human identification protocols. The attack is an application of Coppersmith’s baby-step giant-step algorithm on human identification protcols. Under this attack, the achievable security of some of the best candidates for human identification protocols in the literature is further reduced. We show that our protocol preserves similar usability while achieves better security than these protocols. A comprehensive security analysis is provided which suggests parameters guaranteeing desired levels of security.

On the security of PAS (predicate-based authentication service)

Recently a new human authentication scheme called PAS (predicate-based authentication service) was proposed, which does not require the assistance of any supplementary device. The main security claim of PAS is to resist passive adversaries who can observe the whole authentication session between the human user and the remote server. In this paper we show that PAS is insecure against both brute force attack and a probabilistic attack. In particular, we show that its security against brute force attack was strongly overestimated. Furthermore, we introduce a probabilistic attack, which can break part of the password even with a very small number of observed authentication sessions. Although the proposed attack cannot completely break the password, it can downgrade the PAS system to a much weaker system similar to common OTP (one-time password) systems.

Longitudinal Assessment of Neuropathy in Diabetes using novel ophthalmic MARKers (LANDMark): Baseline findings

Purpose:Over the past decade, corneal nerve morphology and corneal sensation threshold have been explored as potential surrogate markers for the evaluation of diabetic neuropathy. We present the baseline findings of a Longitudinal Assessment of Neuropathy in Diabetes using novel ophthalmic Markers (LANDMark). Methods:The LANDMark Study is a 5-year, two-site, natural history (observational) study of individuals with Type 1 diabetes stratified into those with (T1W) and without (T1WO) neuropathy according to the Toronto criteria, and control subjects. All study participants undergo detailed annual assessment of neuropathy including corneal nerve parameters measured using corneal confocal microscopy and corneal sensitivity measured using non-contact corneal esthesiometry. Results:396 eligible individuals (208 in Brisbane and 188 in Manchester) were assessed: 76 T1W, 166 T1WO and 154 controls. Corneal sensation threshold (mbars) was significantly higher in T1W (1.0 ± 1.1) than T1WO (0.7 ± 0.7) and controls (0.6 ± 0.4) (P=0.002); post-hoc analysis (PHA) revealed no difference between T1WO and controls (Tukey HSD, P=0.502). Corneal nerve fiber length (mm/mm2) (CNFL) was lower in T1W (13.8 ± 6.4) than T1WO (19.1 ± 5.8) and controls (23.2 ± 6.3) (P<0.001); PHA revealed CNFL to be lower in T1W than T1WO, and lower in both of these groups than controls (P<0.001). Corneal nerve branch density (branches/mm2) (CNBD) was significantly lower in T1W (40 ± 32) than T1WO (62 ± 37) and controls (83 ± 46) (P<0.001); PHA showed CNBD was lower in T1W than T1WO, and lower in both groups than controls (P<0.001). Alcohol and cigarette consumption did not differ between groups, although age, BMI, BP, waist circumference, HbA1c, albumin-creatinine ratio, and cholesterol were slightly greater in T1W than T1WO (p<0.05). Some site differences were observed. Conclusions:The LANDMark baseline findings confirm that corneal sensitivity and corneal nerve morphometry can detect differences in neuropathy status in individuals with Type 1 diabetes and healthy controls. Corneal nerve morphology is significantly abnormal even in diabetic patients ‘without neuropathy’ compared to control participants. Results of the longitudinal trial will assess the capability of these tests for monitoring change in these parameters over time as potential surrogate markers for neuropathy.

Organisational culture, leadership behaviour and job satisfaction among primary health care professionals in Saudi Arabia : a mixed-methods study

The purpose of this study was to improve individual and organisational performance in primary health care (PHC) by identifying the relationship between organisational culture, leadership behaviour and job satisfaction. The study used a sequential explanatory mixed methods design, to investigate the relationships between organisational culture, leadership behaviour, and job satisfaction among 550 PHCC professionals in Saudi Arabia. From surveying the PHC professionals, the results highlighted the importance of human caring qualities, including praise and recognition, consideration, and support, with respect to their perceptions of job satisfaction, leadership behaviour, and organisational culture. As a consequence a management framework was proposed to address these issues.

Corneal confocal microscopy shown an improvement in small-fibre neuropathy in subjects with type 1 diabetes on continuous subcutaneous insulin infusion compared to multiple daily injection

Improved glycemic control is the only treatment that has been shown to be effective for diabetic peripheral neuropathy in patients with type 1 diabetes (1). Continuous subcutaneous insulin infusion (CSII) is superior to multiple daily insulin injection (MDI) for reducing HbA1c and hypoglycemic events (2). Here, we have compared the benefits of CSII compared withMDI for neuropathy over 24months....

Management accounting change in a subsidiary organisation

Parent–subsidiary relationships are commonplace nowadays, yet surprisingly there is a paucity of research analysing their dynamics over time. This paper presents a (longitudinal) case study, illuminating the dynamics implicated when a UK chemicals company imposed its systems and rules on a new subsidiary. Drawing on observations from a longitudinal case study (from 1993 to 2001), the study considers: (1) the extent to which a parent imposes its (management accounting) systems,rules and procedures on a subsidiary; (2) the role which (local) political, cultural and institutional factors in a subsidiary play in shaping the dynamics of such change implementation; (3) how new systems and practices become accepted and take root as values and beliefs and how they supplement earlier norms? The study provides insight for the questions above, and draws on institutional theories and a power mobilisation framework to assist in the interpretation of observations. We find that the operations of the subsidiary company are influenced by inter-related forces, both inside and outside the organisation encompassing issues of power, politics and culture. As such, existing institutions in a subsidiary organisation are influenced, sustained, and changed by the socio-economic context in which the subsidiary is located. Organisational practices designed to secure external legitimacy are not however always symbolic and decoupled from internal operations

The perspectives of older drivers on the impact of feedback on their driving behaviours : a qualitative study

Self-regulation is a coping strategy that allows older drivers to drive safely for longer. Self-regulation depends largely on the ability of drivers to evaluate their own driving. Therefore the success of self-regulation, in terms of driving safety, is influenced by the ability of older drivers to have insight into their declining driving performance. In addition, previous studies suggest that providing feedback to older adults regarding their driving skills may lead them to change their driving behaviour. However, little is currently known about the impact of feedback on older drivers’ self-awareness and their subsequent driving regulatory behaviour. This study explored the process of self-regulation and driving cessation among older drivers using the PAPM as a framework. It also investigated older adults’ perceptions and opinions about receiving feedback in regards to their driving abilities. Qualitative focus groups with 27 participants aged 70 years or more were conducted. Thematic analysis resulted in the development of five main themes; the meaning of driving, changes in driving pattern, feedback, the planning process, and solutions. The analysis also resulted in an initial model of driving self-regulation among older drivers that is informed by the current research and the Precaution Adoption Process Model as the theoretical framework. It identifies a number of social, personal, and environmental factors that can either facilitate or hinder people’s transition between stages of change. The findings from this study suggest that further elaboration of the PAPM is needed to take into account the role of insight and feedback on the process of self-regulation among older drivers.

The applicability of the Precaution Adoption Process Model for understanding self-regulatory driving behaviour among older drivers

1. Introduction The success of self-regulation, in terms of enhancing older drivers’ safety and maintaining their mobility, depends largely upon older drivers’ awareness of the declines in their driving abilities. Therefore, interventions targeted at increasing older drivers’ safety should aim to enhance their awareness of their physical, sensory and cognitive limitations. Moreover, previous research suggests that driving behaviour change may occur through stages and that interventions and feedback may be perceived differently at each stage. 2. Study aims To further understand the process of driving self-regulation among older adults by exploring their perceptions and experiences of self-regulation, using the PAPM as a framework. To investigate the possible impact of feedback on their driving on their decision making process. 3. Methodology Research tool: Qualitative focus groups (n=5 sessions) Recruitment: Posters, media, newspaper advertisement and emails Inclusion criteria: Aged 70 or more, English-speaking, current drivers Participants: Convenience sample of 27 men and women aged 74 to 90 in the Sunshine Coast and Brisbane city, Queensland, Australia. 4. Analysis Thematic analysis was conducted following the process outlined by Braun and Clarke (2006) to identify, analyse and report themes within the data. Four main themes were identified.

Foreign-currency and monetary geopolitics of United States and its effects on the future of the international system

The US dollar is still considered as the main strategic deposit among the currencies of different countries of the world and the policies of the World Bank and the International Financial Organizations have been and will always be influenced by the US economy. Despite the economic crises and commercial balance deficits in the United States, dollar has maintained its high position in and its domination over foreign exchanges and foreign-currency deposits of the countries. The novelty of the present research relies on its consideration of the political properties of the governments and the geopolitical effects of these countries on the position of their monetary and foreign-currency policies and consequently, on the international financial organizations such as the International Monetary Fund and the World Bank, which can determine the future of international economy and the political relations among countries. Our research proves that the political development of the United States and its geopolitical situation have been of the effective factors on dollar growth; and unless the competitors acquire such a relative advantage, they will not be able to seriously challenge the currency of dollar and the monetary policies of the United States, at least in a short time