HMOG: New Behavioral Biometric Features for Continuous Authentication of Smartphone Users

We introduce hand movement, orientation, and grasp (HMOG), a set of behavioral features to continuously authenticate smartphone users. HMOG features unobtrusively capture subtle micro-movement and orientation dynamics resulting from how a user grasps, holds, and taps on the smartphone. We evaluated authentication and biometric key generation (BKG) performance of HMOG features on data collected from 100 subjects typing on a virtual keyboard. Data were collected under two conditions: 1) sitting and 2) walking. We achieved authentication equal error rates (EERs) as low as 7.16% (walking) and 10.05% (sitting) when we combined HMOG, tap, and keystroke features. We performed experiments to investigate why HMOG features perform well during walking. Our results suggest that this is due to the ability of HMOG features to capture distinctive body movements caused by walking, in addition to the hand-movement dynamics from taps. With BKG, we achieved the EERs of 15.1% using HMOG combined with taps. In comparison, BKG using tap, key hold, and swipe features had EERs between 25.7% and 34.2%. We also analyzed the energy consumption of HMOG feature extraction and computation. Our analysis shows that HMOG features extracted at a 16-Hz sensor sampling rate incurred a minor overhead of 7.9% without sacrificing authentication accuracy. Two points distinguish our work from current literature: 1) we present the results of a comprehensive evaluation of three types of features (HMOG, keystroke, and tap) and their combinations under the same experimental conditions and 2) we analyze the features from three perspectives (authentication, BKG, and energy consumption on smartphones)

Can we successfully avoid persistent contrails by small altitude adjustments of flights in the real world?

This paper describes the first-ever operational contrail avoidance trial in the real world, which took place in the region of Maastricht Upper Area Control (including the northwest of Germany, the Benelux countries and part of the North Sea) in the year 2021. Contrail avoidance could be an efficient method for mitigating the climate impact of aviation. Applying a deliberate experiment design, air traffic was deviated every other day by changing the flight altitude by up to 2000 ft up or down if potential persistent contrails were predicted. Whether deviations were successful on average was checked using satellite images of high clouds and by application of a contrail detection algorithm, which makes use of the properties of contrails. Despite the fact that forecasting persistent contrails remains a challenge, the trial was successful at a significance level of 97.5 %, i.e., on average persistent contrails can be avoided for regular flights in the real world with a small intervention in the vertical flight path. The experiment is an important step towards a regular operational reduction of the aviation climate impact by means of air traffic management. Nevertheless, many open questions need to be solved prior to an operational implementation of contrail avoidance or climate optimised flight trajectories in legal ATM procedures

Can we successfully avoid persistent contrails by small altitude adjustments of flights in the real world?

This paper describes the first-ever operational contrail avoidance trial in the real world, which took place in the region of Maastricht Upper Area Control (including the northwest of Germany, the Benelux countries and part of the North Sea) in the year 2021. Contrail avoidance could be an efficient method for mitigating the climate impact of aviation. Applying a deliberate experiment design, air traffic was deviated every other day by changing the flight altitude by up to 2000 ft up or down if potential persistent contrails were predicted. Whether deviations were successful on average was checked using satellite images of high clouds and by application of a contrail detection algorithm, which makes use of the properties of contrails. Despite the fact that forecasting persistent contrails remains a challenge, the trial was successful at a significance level of 97.5 %, i.e., on average persistent contrails can be avoided for regular flights in the real world with a small intervention in the vertical flight path. The experiment is an important step towards a regular operational reduction of the aviation climate impact by means of air traffic management. Nevertheless, many open questions need to be solved prior to an operational implementation of contrail avoidance or climate optimised flight trajectories in legal ATM procedures

An efficient biometric-based continuous authentication scheme with HMM prehensile movements modeling

International audienceBiometric is an emerging technique for user authentication thanks to its efficiency compared to the traditional methods, such as passwords and access-cards. However, most existing biometric authentication systems require the cooperation of users and provide only a login time authentication. To address these drawbacks, we propose in this paper a new, efficient continuous authentication scheme based on the newly biometric trait that still under development: prehensile movements. In this work, we model the movements through Hidden Markov Model-Universal Background Model (HMM-UBM) with continuous observations based on Gaussian Mixture Model (GMM). Unlike the literature, the gravity signal is included. The results of the experiments conducted on a public database HMOG and on a proprietary database, collected under uncontrolled conditions, have shown that prehensile movements are very promising. This new biometric feature will allow users to be authenticated continuously, passively and in real time