45,869 research outputs found
GeoNotes: A Location-based Information System for Public Spaces
The basic idea behind location-based information systems is to connect information pieces to positions in outdoor or indoor space. Through position technologies such as Global Positioning System (GPS), GSM positioning, Wireless LAN positioning o
DeSyRe: on-Demand System Reliability
The DeSyRe project builds on-demand adaptive and reliable Systems-on-Chips (SoCs). As fabrication technology scales down, chips are becoming less reliable, thereby incurring increased power and performance costs for fault tolerance. To make matters worse, power density is becoming a significant limiting factor in SoC design, in general. In the face of such changes in the technological landscape, current solutions for fault tolerance are expected to introduce excessive overheads in future systems. Moreover, attempting to design and manufacture a totally defect and fault-free system, would impact heavily, even prohibitively, the design, manufacturing, and testing costs, as well as the system performance and power consumption. In this context, DeSyRe delivers a new generation of systems that are reliable by design at well-balanced power, performance, and design costs. In our attempt to reduce the overheads of fault-tolerance, only a small fraction of the chip is built to be fault-free. This fault-free part is then employed to manage the remaining fault-prone resources of the SoC. The DeSyRe framework is applied to two medical systems with high safety requirements (measured using the IEC 61508 functional safety standard) and tight power and performance constraints
A watchdog processor to detect data and control flow errors
A watchdog processor for the MOTOROLA M68040 microprocessor is presented. Its main task is to protect from transient faults caused by SEUs the transmission of data between the processor and the system memory, and to ensure a correct instructions' flow, just monitoring the external bus, without modifying the internal architecture of the M68040. A description of the principal procedures is given, together with the method used for monitoring the instructions' flow
Interleaving Command Sequences: a Threat to Secure Smartcard Interoperability
The increasingly widespread use of smartcards for a variety of sensitive
applications, including digital signatures, creates the need to ensure and
possibly certify the secure interoperability of these devices. Standard
certification criteria, in particular the Common Criteria, define security
requirements but do not sufficiently address the problem of interoperability.
Here we consider the interoperability problem which arises when various
applications interact with different smartcards through a middleware. In such a
situation it is possible that a smartcard of type S receives commands that were
supposed to be executed on a different smartcard of type S'. Such "external
commands" can interleave with the commands that were supposed to be executed on
S. We experimentally demonstrate this problem with a Common Criteria certified
digital signature process on a commercially available smartcard. Importantly,
in some of these cases the digital signature processes terminate without
generating an error message or warning to the user.Comment: 6 pages; published in the 10th WSEAS International Conference on
Information Security and Privacy (ISP 2011
An Experimental Microarchitecture for a Superconducting Quantum Processor
Quantum computers promise to solve certain problems that are intractable for
classical computers, such as factoring large numbers and simulating quantum
systems. To date, research in quantum computer engineering has focused
primarily at opposite ends of the required system stack: devising high-level
programming languages and compilers to describe and optimize quantum
algorithms, and building reliable low-level quantum hardware. Relatively little
attention has been given to using the compiler output to fully control the
operations on experimental quantum processors. Bridging this gap, we propose
and build a prototype of a flexible control microarchitecture supporting
quantum-classical mixed code for a superconducting quantum processor. The
microarchitecture is based on three core elements: (i) a codeword-based event
control scheme, (ii) queue-based precise event timing control, and (iii) a
flexible multilevel instruction decoding mechanism for control. We design a set
of quantum microinstructions that allows flexible control of quantum operations
with precise timing. We demonstrate the microarchitecture and microinstruction
set by performing a standard gate-characterization experiment on a transmon
qubit.Comment: 13 pages including reference. 9 figure
- …