GPS-assisted Femtocell Synchronization and Localization Through Tightly-Coupled OpportunisticNavigation

Aerospace Engineering and Engineering Mechanic

The Texas Spoofing Test Battery: Toward a Standard for Evaluating GPS Signal Authentication Techniques

A battery of recorded spoofing scenarios has been compiled for evaluating civil Global Positioning System (GPS) signal authentication techniques. The battery can be considered the data component of an evolving standard meant to define the notion of spoof resistance for commercial GPS receivers. The setup used to record the scenarios is described. A detailed description of each scenario reveals readily detectable anomalies that spoofing detectors could target to improve GPS securityAerospace Engineering and Engineering Mechanic

A Testbed for Developing and Evaluating GNSS Signal Authentication Techniques

An experimental testbed has been created for developing and evaluating Global Navigation Satellite System (GNSS) signal authentication techniques. The testbed advances the state of the art in GNSS signal authentication by subjecting candidate techniques to the strongest publicly-acknowledged GNSS spoofing attacks. The testbed consists of a real-time phase-coherent GNSS signal simulator that acts as spoofer, a real-time softwaredefined GNSS receiver that plays the role of defender, and post-processing versions of both the spoofer and defender. Two recently-proposed authentication techniques are analytically and experimentally evaluated: (1) a defense based on anomalous received power in a GNSS band, and (2) a cryptographic defense against estimation-and-replay-type spoofing attacks. The evaluation reveals weaknesses in both techniques; nonetheless, both significantly complicate a successful GNSS spoofing attackAerospace Engineering and Engineering Mechanic

Fluid characteristics in hydrothermal veins of the Twangiza-Namoya Gold Belt, South Kivu and Maniema Provinces, DRC

This study evaluates fluid variations in hydrothermal quartz veins from gold deposits in Kamiuga, Lugushwa and Namoya, located in the Twangiza-Namoya Gold Belt (TNGB) of the Kibara Belt in the eastern Democratic Republic of the Congo (DRC. Petrographic, fluid inclusion (FI) microthermometric observations and Raman spectroscopy provided qualitative and quantitative fluid composition data on the hydrothermal and magmatic fluids and their evolution during mineral precipitation. The formational fluids, based on genetically specific characteristics, were categorized into six distinct FI Types. Type 1 to 4 FIs are common in all TNGB fluids. Type 1 and 2 FIs are high salinity halite bearing FIs that indicate formation fluids that are predominantly metamorphic-sedimentary in source. CO2 vapour-bearing and the aqueous-saline CO2 liquid-bearing Type 3 FIs commonly contain CH4 and/or N2. Type 4 FIs are saline aqueous and commonly co-genetic with Type 1 and 2 FIs. Type 5 CO2-rich FIs contain either sulphide crystals, amorphous or crystalline carbon. Type 3 and 5 FIs indicate fluid sources rich in organic materials. Type 6 single aqueous-liquid phase FIs have no apour bubble, lacked a visible phase change on heating and were not thermometrically evaluated. The data indicated a high correlation between fluid composition and gold grades. High Au grade veins correlate with CO2 bearing Type 3 and 5 FIs -predominantly liquid-bearing CO2 fluids and quartz veins and fluids that contain increased organic material and sulphides. The polyphase quartz veins show highly variable homogenisation and formational temperatures exceeding 400°C. Formation conditions indicate high trapping temperatures in relation to the pressures at which fluids were captured. The high depth-temperature gradients are likely associated with mesothermal orogenic go ld deposition. Mineralisation is interpreted to have taken place as a result of mobilisation of fluids during the Pan African orogeny. Based on fluid petrography and microthermometry, gold mineralisation is most likely associated with secondary fluid influx from metamorphic sedimentary sourrces such as metapelites. The correlation between high gold grades and secondary fluids containing sulphides, high depth-temperature gradients, elevated CO2, CH4 and organic materials suggest black shales as a possible primary fluid and gold source. The development of variable and multiple fluid influx events and interactions with host rocks and imported materials resulted in complex polyphase quartz veins; the product of which created viable gold deposits throughout the TNGB. The six FI Types provides evidence of the diversity in the formation and evolution of gold deposits in the TNGB

Practical Cryptographic Civil GPS Signal Authentication

Abstract-A practical technique is proposed to authenticate civil GPS signals. The technique combines cryptographic authentication of the GPS navigation message with signal timing authentication based on statistical hypothesis tests to secure civil GPS receivers against spoofing attacks. The notion of GNSS signal authentication is defined in probabilistic terms. Candidate GPS signal authentication schemes are evaluated in terms of effectiveness and practicality leading to a proposal for incorporating digital signatures into the extensible GPS civil navigation (CNAV) message. The proposal is sufficiently detailed to facilitate near-term implementation of security-hardened civil GPS

JWST observations of the Ring Nebula (NGC 6720): I. Imaging of the rings, globules, and arcs

We present JWST images of the well-known planetary nebula NGC 6720 (the Ring Nebula), covering wavelengths from 1.6$\mu$m to 25 $\mu$m. The bright shell is strongly fragmented with some 20 000 dense globules, bright in H$_2$, with a characteristic diameter of 0.2 arcsec and density $n_{\rm H} \sim 10^5$-$10^6$ cm$^{-3}$. The shell contains a thin ring of polycyclic aromatic hydrocarbon (PAH) emission. H$_2$ is found throughout the shell and in the halo. H$_2$ in the halo may be located on the swept-up walls of a biconal polar flow. The central cavity is shown to be filled with high ionization gas and shows two linear structures. The central star is located 2 arcsec from the emission centroid of the cavity and shell. Linear features (`spikes') extend outward from the ring, pointing away from the central star. Hydrodynamical simulations are shown which reproduce the clumping and possibly the spikes. Around ten low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280 yr. A previously known much wider companion is located at a projected separation of about 15 000 au; we show that it is an M2-M4 dwarf. The system is therefore a triple star. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC 3132) and may be a common aspect of such nebulae.Comment: 25 pages, 23 figures. Submitted to Monthly Notices of the Royal Astronomical Society. Corrected typos in metadat

<i>JWST</i> observations of the Ring Nebula (NGC 6720): I. Imaging of the rings, globules, and arcs

We present $\textit{JWST}$ images of the well-known planetary nebula NGC 6720 (the Ring Nebula), covering wavelengths from 1.6$\mu$m to 25$\mu$m. The bright shell is strongly fragmented with some 20 000 dense globules, bright in $H_2$, with a characteristic diameter of 0.2 arcsec and density $n_H$ ∼ $10^5$–$10^6$ $\textit{cm}$$^{-3}$. The shell contains a narrow ring of polycyclic aromatic hydrocarbon (PAH) emission. $H_2$ is found throughout the shell and also in the halo. $H_2$ in the halo may be located on the swept-up walls of a biconal polar flow. The central cavity is filled with high ionization gas and shows two linear structures which we suggest are the edges of a biconal flow, seen in projection against the cavity. The central star is located 2 arcsec from the emission centroid of the cavity and shell. Linear features (‘spikes’) extend outward from the ring, pointing away from the central star. Hydrodynamical simulations reproduce the clumping and possibly the spikes. Around ten low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280 yr. A previously known much wider companion is located at a projected separation of about 15 000 au; we show that it is an M2–M4 dwarf. NGC 6720 is therefore a triple star system. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC 3132) and may be a common aspect of such nebulae

Brazilian Consensus on Photoprotection

Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of nonmelanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection

GPS Spoofing & Implications for Telecom

Aerospace Engineering and Engineering Mechanic

Secure navigation and timing without local storage of secret keys

textCivil Global Navigation Satellite System (GNSS) signals are broadcast unencrypted worldwide according to an open-access standard. The virtues of open-access and global availability have made GNSS a huge success. Yet the transparency and predictability of these signals renders them easy to counterfeit, or spoof. During a spoofing attack, a malefactor broadcasts counterfeit GNSS signals that deceive a victim receiver into reporting the spoofer-controlled position or time. Given the extensive integration of civil GNSS into critical national infrastructure and safety-of-life applications, a successful spoofing attack could have serious and significant consequences. Unlike civil GNSS signals, military GNSS signals employ symmetric-key encryption, which serves as a defense against spoofing attacks and as a barrier to unauthorized access. Despite the effectiveness of the symmetric-key approach, it has significant drawbacks and is impractical for civil applications. First, symmetric-key encryption requires tamper-resistant receivers to protect the secret keys from unauthorized discovery and dissemination. Manufacturing a tamper-resistant receiver increases cost and limits manufacturing to trusted foundries. Second, key management is problematic and burdensome despite the recent introduction of over-the-air keying. Third, even symmetric-key encryption remains somewhat vulnerable to specialized spoofing attacks. I propose an entirely new approach to navigation and timing security that avoids the shortcomings of the symmetric-key approach while maintaining a high resistance to spoofing. My first contribution is a probabilistic framework that develops necessary components of signal authentication. Based on the framework, I develop an asymmetric-key cryptographic signal authentication technique and a non-cryptographic spoofing detection technique, both of which operate without a secret key stored locally in a secure receiver. These anti-spoofing techniques constitute the remaining two contributions of this dissertation. They stand as viable spoofing defenses for civil users and could augment---or even replace---current and planned military anti-spoofing measures. Finally, I offer an in-depth case study of the security vulnerabilities and possible cryptographic enhancements of a modern GNSS-based aviation surveillance technology in the context of the technical and regulatory aviation environment.Electrical and Computer Engineerin