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Authenticated broadcast with a partially compromised public-key infrastructure

February 1, 2014
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Journal Article
Author:
S. Dov Gordon
…
Published in:
Info. and Comput., Vol. 234, February 2014, pp. 17-25.
Topic:
cryptography
R&D area:
R&D group:

Summary

Given a public-key infrastructure (PKI) and digital signatures, it is possible to construct broadcast protocols tolerating any number of corrupted parties. Existing protocols, however, do not distinguish between corrupted parties who do not follow the protocol, and honest parties whose secret (signing) keys have been compromised but continue to behave honestly. We explore conditions under which it is possible to construct broadcast protocols that still provide the usual guarantees (i.e., validity/agreement) to the latter. Consider a network of n parties, where an adversary has compromised the secret keys of up to tc honest parties, where an adversary has compromised the secret keys of up to tc honest parties and, in addition, fully controls the behavior of up to ta other parties. We show that for any fixed tc>0 and any fixed ta, there exists an efficient protocol for broadcast if and only if 2 ta + min (ta, tc) < n. (When tc = 0, standard results imply feasibility for all ta < n.) We also show that if tc, ta are not fixed, but are only guaranteed to satisfy the above bound, then broadcast is impossible to achieve except for a few specific values of n; for these "exceptional" values of n, we demonstrate broadcast protocols. Taken together, our results give a complete characterization of this problem.
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Summary

Given a public-key infrastructure (PKI) and digital signatures, it is possible to construct broadcast protocols tolerating any number of corrupted parties. Existing protocols, however, do not distinguish between corrupted parties who do not follow the protocol, and honest parties whose secret (signing) keys have been compromised but continue to behave...

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Authenticated broadcast with a partially compromised public-key infrastructure

Initial assessment of wind forecasts for Airport Acceptance Rate (AAR) and Ground Delay Program (GDP) planning

January 29, 2014
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Project Report
Author:
Richard A. DeLaura
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Published in:
MIT Lincoln Laboratory Report ATC-414
Topic:
weather
R&D area:
R&D group:

Summary

The planning and execution of the Airport Acceptance Rate (AAR) for major metroplex airports is a complex and critical function of traffic managers in the National Airspace System (NAS). Despite the importance of AAR planning, traffic managers currently have no widely available decision support to provide guidance for runway selection and the determination of a sustainable AAR. The AAR Decision Support Capability (AARDSC), currently under development as part of the Collaborative Air Traffic Management Technology Work Package 4 (CATMT WP4), will provide such guidance. This report provides an initial analysis of the impacts of surface winds and winds aloft on the key factors associated with the AAR (the selection of runway configuration and aircraft ground speed and spacing on final approach) and the capabilities of currently available weather forecasts to accurately predict those impacts. The report was limited in scope by the schedule and available resources, and is intended as a foundation for a comprehensive forecast assessment in follow-on work. Surface wind forecasts from the Terminal Aerodome Forecast (TAF) and numerical prediction models (the High Resolution Rapid Refresh [HRRR], Rapid Refresh [RAP] and Rapid Update Cycle [RUC], collectively described as "MODEL") were compared to observed winds gathered from METAR reports as Newark International Airport (EWR). TAF and METAR were compared for 639 days of operations from 2011-2013. MODEL forecasts and METAR were compared for 21 days of operation, 16 of which had Traffic Management Initiatives (TMI) in place to mitigate adverse weather impacts. Winds aloft were translated into several wind impact metrics. The impacts of winds aloft forecast errors were evaluated by comparing impact metrics calculated from MODEL forecasts with those calculated from analysis fields for the 21 case days. Forecasts were evaluated at horizons of 2, 4, 6, and 8 hours.
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Summary

The planning and execution of the Airport Acceptance Rate (AAR) for major metroplex airports is a complex and critical function of traffic managers in the National Airspace System (NAS). Despite the importance of AAR planning, traffic managers currently have no widely available decision support to provide guidance for runway selection...

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Initial assessment of wind forecasts for Airport Acceptance Rate (AAR) and Ground Delay Program (GDP) planning

Adaptive RF canceller for transmit-receive isolation improvement

January 19, 2014
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Conference Paper
Author:
Kenneth E. Kolodziej
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Published in:
2014 IEEE Radio and Wireless Symposium (RWS), 19-23 January 2014.
Topic:
antennas
R&D area:
R&D group:

Summary

For effective operation, Simultaneous Transmit and Receive (STAR) systems require high isolation between the transmitted signals and the receiver input, the absence of which can lead to the saturation of a receiver's front end. This paper presents an adaptive RF canceller used to improve isolation. The canceller is configured as an RD tapped delay line with four taps, each with independent amplitude and phase weights that are tuned by a Dithered Linear Search algorithm. This canceller produces 30 dB of signal cancellation over a 20 MHz bandwidth centered at 2.45 GHz in an isolated environment. When combined with a high-isolation antenna, an overall STAR system isolation of 90 dB is achieved, while also maintaining omnidirectional transmit and receive antenna patterns.
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Summary

For effective operation, Simultaneous Transmit and Receive (STAR) systems require high isolation between the transmitted signals and the receiver input, the absence of which can lead to the saturation of a receiver's front end. This paper presents an adaptive RF canceller used to improve isolation. The canceller is configured as...

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Adaptive RF canceller for transmit-receive isolation improvement

Insensitivity of the rate of ion motional heating to trap-electrode material over a large temperature range

January 16, 2014
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Journal Article
Author:
John Chiaverini
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Published in:
Phys. Rev. A, At. Mol. Opt. Phys., Vol. 89, No. 1, 2014, 012318.
Topic:
advanced materials
R&D area:
R&D group:

Summary

We present measurements of trapped-ion motional-state heating rates in niobium and gold surface-electrode ion traps over a range of trap-electrode temperatures from approximately 4 K to room temperature (295 K) in a single apparatus. Using the sideband-ratio technique after resolved-sideband cooling of single ions to the motional ground state, we find low-temperature heating rates more than two orders of magnitude below the room-temperature values and approximately equal to the lowest measured heating rates in similarly sized cryogenic traps. We find similar behavior in the two very different electrode materials, suggesting that the anomalous heating process is dominated by non-material-specific surface contaminants. Through precise control of the temperature of cryopumping surfaces, we also identify conditions under which elastic collisions with the background gas can lead to an apparent steady heating rate, despite rare collisions.
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Summary

We present measurements of trapped-ion motional-state heating rates in niobium and gold surface-electrode ion traps over a range of trap-electrode temperatures from approximately 4 K to room temperature (295 K) in a single apparatus. Using the sideband-ratio technique after resolved-sideband cooling of single ions to the motional ground state, we...

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Insensitivity of the rate of ion motional heating to trap-electrode material over a large temperature range

A frequency selective atom interferometer magnetometer

January 13, 2014
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Journal Article
Author:
Danielle A. Braje
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Published in:
J. Mod. Opt., Vol. 61, No. 1, 2014, pp. 61-71.
Topic:
optics
R&D area:
R&D group:

Summary

In this article, we discuss the magnetic-field frequency selectivity of a time-domain interferometer based on the number and timing of intermediate pi pulses. We theoretically show that by adjusting the number of pi pulses and the pi-pulse timing, we can control the frequency selectivity of the interferometer to time varying and DC magnetic fields. We present experimental data demonstrating increased coherence time due to bandwidth filtering with the inclusion of a pi pulse between the initial and final pi/2 pulses, which mitigates sensitivity to low frequency magnetic fields.
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Summary

In this article, we discuss the magnetic-field frequency selectivity of a time-domain interferometer based on the number and timing of intermediate pi pulses. We theoretically show that by adjusting the number of pi pulses and the pi-pulse timing, we can control the frequency selectivity of the interferometer to time varying...

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A frequency selective atom interferometer magnetometer

Characterizing phonetic transformations and acoustic differences across English dialects

January 1, 2014
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Journal Article
Author:
Nancy Chen
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Published in:
IEEE Trans. Audio, Speech, and Lang. Process., Vol. 22, No. 1, January 2014, pp. 110-24.
Topic:
language recognition
R&D area:
R&D group:

Summary

In this work, we propose a framework that automatically discovers dialect-specific phonetic rules. These rules characterize when certain phonetic or acoustic transformations occur across dialects. To explicitly characterize these dialect-specific rules, we adapt the conventional hidden Markov model to handle insertion and deletion transformations. The proposed framework is able to convert pronunciation of one dialect to another using learned rules, recognize dialects using learned rules, retrieve dialect-specific regions, and refine linguistic rules. Potential applications of our proposed framework include computer-assisted language learning, sociolinguistics, and diagnosis tools for phonological disorders.
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Summary

In this work, we propose a framework that automatically discovers dialect-specific phonetic rules. These rules characterize when certain phonetic or acoustic transformations occur across dialects. To explicitly characterize these dialect-specific rules, we adapt the conventional hidden Markov model to handle insertion and deletion transformations. The proposed framework is able to...

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Characterizing phonetic transformations and acoustic differences across English dialects

Transactional array reconciliation tomography for precision indoor location

January 1, 2014
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Journal Article
Author:
Vincent T. Amendolare
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Published in:
IEEE T. Aero. Elec. Sys. Vol. 50, No. 1 January 2014, pp. 17-32.
Topic:
antennas
R&D area:
R&D group:

Summary

A novel system is described for precision indoor location and tracking of personnel inside a building using RF signals exchanged with reference units deployed outside the building without benefit of infrastructure or site survey. Localization in high multipath without multilateration by fusion of unidirectional signals using singular array reconciliation tomography is reviewed. The bidirectional signal fusion approach is introduced with transactional array reconciliation tomography. Underlying theory is developed, and performance evaluated with simulated and experimental data.
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Summary

A novel system is described for precision indoor location and tracking of personnel inside a building using RF signals exchanged with reference units deployed outside the building without benefit of infrastructure or site survey. Localization in high multipath without multilateration by fusion of unidirectional signals using singular array reconciliation tomography...

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Transactional array reconciliation tomography for precision indoor location

Content + context networks for user classification in Twitter

December 9, 2013
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Conference Paper
Author:
William M. Campbell
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Published in:
Frontiers of Network Analysis, NIPS Workshop, 9 December 2013.
Topic:
human language technology
R&D area:
R&D group:

Summary

Twitter is a massive platform for open communication between diverse groups of people. While traditional media segregates the world's population on lines of language, age, physical location, social status, and many other characteristics, Twitter cuts through these divides. The result is an extremely diverse social network. In this work, we combine features of this network structure with content analytics on the tweets in order to create a content + context network, capturing the relations not only between people, but also between people and content and between content and content. This rich structure allows deep analysis into many aspects of communication over Twitter. We focus on predicting user classifications by using relational probability trees with features from content + context networks. Experiments demonstrate that these features are salient and complementary for user classification.
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Summary

Twitter is a massive platform for open communication between diverse groups of people. While traditional media segregates the world's population on lines of language, age, physical location, social status, and many other characteristics, Twitter cuts through these divides. The result is an extremely diverse social network. In this work, we...

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Content + context networks for user classification in Twitter

Optimizing media access strategy for competing cognitive radio networks

December 9, 2013
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Conference Paper
Author:
Youngjune L. Gwon
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Published in:
GLOBECOM 2013: 2013 IEEE Global Communications Conf., 9-13 December 2013.
Topic:
communications
R&D area:
R&D group:

Summary

This paper describes an adaptation of cognitive radio technology for tactical wireless networking. We introduce Competing Cognitive Radio Network (CCRN) featuring both communicator and jamming cognitive radio nodes that strategize in taking actions on an open spectrum under the presence of adversarial threats. We present the problem in the Multi-armed Bandit (MAB) framework and develop the optimal media access strategy consisting of mixed communicator and jammer actions in a Bayesian setting for Thompson sampling based on extreme value theory. Empirical results are promising that the proposed strategy seems to outperform Lai & Robbins and UCB, some of the most important MAB algorithms known to date.
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Summary

This paper describes an adaptation of cognitive radio technology for tactical wireless networking. We introduce Competing Cognitive Radio Network (CCRN) featuring both communicator and jamming cognitive radio nodes that strategize in taking actions on an open spectrum under the presence of adversarial threats. We present the problem in the Multi-armed...

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Optimizing media access strategy for competing cognitive radio networks

Quantum information processing using quasiclassical electromagnetic interactions between qubits and electrical resonators

December 6, 2013
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Journal Article
Author:
Andrew J. Kerman
Published in:
New J. Phys., Vol. 15, 2013, 123011.
Topic:
quantum
R&D area:
R&D group:

Summary

Electrical resonators are widely used in quantum information processing, by engineering an electromagnetic interaction with qubits based on real or virtual exchange of microwave photons. This interaction relies on strong coupling between the qubits' transition dipole moments and the vacuum fluctuations of the resonator in the same manner as cavity quantum electrodynamics (QED), and has consequently come to be called 'circuit QED' (cQED). Great strides in the control of quantum information have already been made experimentally using this idea. However, the central role played by photon exchange induced by quantum fluctuations in cQED does result in some characteristic limitations. In this paper, we discuss an alternative method for coupling qubits electromagnetically via a resonator, in which no photons are exchanged, and where the resonator need not have strong quantum fluctuations. Instead, the interaction can be viewed in terms of classical, effective 'forces' exerted by the qubits on the resonator, and the resulting resonator dynamics used to produce qubit entanglement are purely classical nature. We show how this type of interaction is similar to that encountered in the manipulation of atomic ion qubits, and we exploit this analogy to construct two-qubit entangling operations that are largely insensitive to thermal or other noise in the resonator, and to its quality factor. These operations are also extensisble to larger numbers of qubits, allowing interactions to be selectively generated among any desired subset of those coupled to a single resonator. Our proposal is potentially applicable to a variety of physical qubit modalities, including superconducting and semiconducting solid-state qubits, trapped molecular ions, and possibly even electron spins in solids.
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Summary

Electrical resonators are widely used in quantum information processing, by engineering an electromagnetic interaction with qubits based on real or virtual exchange of microwave photons. This interaction relies on strong coupling between the qubits' transition dipole moments and the vacuum fluctuations of the resonator in the same manner as cavity...

READ MORE
Quantum information processing using quasiclassical electromagnetic interactions between qubits and electrical resonators
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