Sealed Computation: Abstract Requirements for Mechanisms to Support Trustworthy Cloud Computing

In cloud computing, data processing is delegated to a remote party for efficiency and flexibility reasons. A practical user requirement usually is that the confidentiality and integrity of data processing needs to be protected. In the common scenarios of cloud computing today, this can only be achieved by assuming that the remote party does not in any form act maliciously. In this paper, we propose an approach that avoids having to trust a single entity. Our approach is based on two concepts: (1) the technical abstraction of sealed computation, i.e., a technical mechanism to confine the processing of data within a tamper-proof hardware container, and (2) the additional role of an auditing party that itself cannot add functionality to the system but is able to check whether the system (including the mechanism for sealed computation) works as expected. We discuss the abstract technical and procedural requirements of these concepts and explain how they can be applied in practice

Lightweight Roots of Trust for Modern Systems-on-Chip

The electronics industry is incredibly fast-moving and has greatly impacted our society. One of its evolutions is that smaller and smaller devices are increasingly distributed. The Internet of Things, where an ad-hoc network connects heterogenous devices, like a thermostat or a fridge, is the next evolution in this area. Although these evolutions result in innovative applications, they also give rise to dangerous security risks that are often ignored, and need to be addressed. For example, an attacker who has access to the remote update feature of a pacemaker could use it to install a malicious version of the firmware without the patient's consent, potentially killing them. Another example is that sensors found in a modern car's braking systems could have been modified to report false data. Finally, the Stuxnet attack on Iran's Natanz facility illustrates the potentially catastrophic repercussions of a complex cyber attack. Trusted computing technology guarantees that a device will behave in the expected manner for the intended purpose. The objective of this project is to design minimal trust architectures for modern Systems-on-Chip. Their design is very challenging for four reasons. First, new attack vectors emerge frequently and need to be protected against. Second, the architectures have to be designed for new digital platforms, like many-core Systems-on-Chip with Networks-on-Chip. Third, they have to be extremely lightweight: embedded devices often have real-time execution deadlines and need to be very energy-efficient. Finally, the designed mechanisms should also be flexible, so that they can be adapted to any processing environment. The first goal of this work is to develop new security architectures for embedded devices, both for single- and multi-core SoCs. The second goal is to improve the security of Networks-on-Chip in the context of many-core SoCs. More specifically, a trust mechanism for the InvasIC platform will be developed.status: publishe

Time-dependent transition probabilities and the assessment of seasonal effects on within-day variations in chewing behaviour of housed sheep

State transitions in the chewing behaviour of six half-breed (Ile de France X Texel) yearling female sheep (Ovis aries L.) were studied by using jaw movements recorded continuously over 5 days at the end of a number of experimental periods from 21 September 1992 to 4 April 1993. The sheep were housed in individual pens. Each of them received the same diet, that is, 250 g/day of concentrate mix (15.5% crude protein (CP), 36.5% neutral detergent fibre (NDF)) fed at 0900 h and natural grass hay (6.7% CP, 69.1% NDF) fed ad libitum at 0915 and 1600 h. Mineral salt blocks and water were continuously available. The main objective was to assess seasonal effects on within-day variations in the chewing behaviour of sheep, at small to large time scales within a day. We therefore focused on two experimental periods characterised by contrasting conditions of daylength and temperature(i.e., 'Period 1': 610 min daylight, mean temperature of 10.9 degrees C, and 'Period 4': 550 min daylight, mean temperature of 7.2 degrees C). In particular, differences between periods in the nycterohemeral pattern of chewing behaviour and the quality of forecasts of chewing states were tested. We submitted our data to a new method of analysis that we developed: the method of time-dependent transition probabilities, and compared the results to those obtained using other methods that were available in the literature. Overall, the sheep spent more time eating in Period 1 than in Period 4. Specifically, a secondary peak in eating activity, which was observed in the early afternoon in Period 1, was absent in Period 4. The nycterohemeral pattern of eating activity showed significant differences between periods, at the main rhythmic component of 24 h and at short components around 2 h. Such differences were not observed for ruminating and idling activities. The quality of forecasts of chewing states decreased from Periods 1 to 4, in terms of accuracy (based on R-2) and lead of reliable forecasts (i.e., forecast - observation < 0.1). The most (least) accurate forecasts were obtained for the ruminating (eating) state in both periods. We have attributed the differences that we found between periods to daylength instead of temperature because the sheep were mostly within the thermoneutral zone in our study. By comparison, using mean hourly times of eating activity, significant differences between periods were detected for the 24-h rhythmic component and the 4-h component, instead of the 2-h component, probably because of aliasing (i.e., when the sampling time interval used is longer than suited; the minute was found to be a suitable interval length in the calculation of time-dependent transition probabilities). Using the age-dependent model of Rook and Penning, minor differences between periods were detected. On that basis, the method of time-dependent transition probabilities may be brought forward as a complement of value to existing methods of behavioural data analysis. (C) 2000 Elsevier Science B.V. All rights reserved

Grating transition radiation: A source of quasimonochromatic radiation.

International audienceWe have observed transition radiation at optical wavelengths, emitted by 3-13-MeV electrons interacting with a diffraction grating. Near the direction of specular reflection we observed broadband radiation with the same properties as optical transition radiation from a flat surface. In addition, at large angles with respect to this direction and for low angles of incidence of the electrons on the grating surface, we observed the emission of quasimonochromatic radiation. This grating transition radiation may offer an alternative method for production of quasimonochromatic radiation in the far-infrared to mm wavelength range

Effect of the inclusion time of extruded linseed supplementation before slaughter on n-3 fatty acids enrichment of chicken meat.

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