Di Qiu

Ionospheric Threat Parameterization for Local Area Global-Positioning-System-Based Aircraft Landing Systems

Observations of extreme spatial rates of change of ionospheric electron content and the characterization strategy for mitigation applied by the U.S. local area augmentation system are shown. During extreme ionospheric activity, the gradient suffered by a global navigation satellite system user a few kilometers away from a ground reference station may reach as high as 425 mm of delay (at the GPS L1frequency) per km of user separation. The method of data analysis that produced these results is described, and a threat space that parameterizes these possible threats to user integrity is defined. Certain configurations of user, reference station, global navigation satellite system satellite, and ionospheric storm-enhanced density may inhibit detection of the anomalous ionosphere by the reference station.

Security from Location

The emergence of the Internet and personal computers has led to an age of unprecedented information content and access. The proliferation of Internet connectivity, personal computers, and portable, high density data storage has put volumes of data are at one’s fingertips. While the spread of such technology has increased efficiency and knowledge, it has also made information theft easier and more damaging.

A measure of Loran location-based information

In cryptography, a verification tag is a piece of information used to authenticate a message. In geoencryption, location-based information is defined as the amount of information that can be used to construct a verification tag or ldquogeotagrdquo to identify onepsilas location. The term ldquogeoencryptionrdquo or ldquolocation-based encryptionrdquo refers to a security algorithm that limits the access or decryption of information content to specified locations and/or times. Loran is chosen as a case study to implement geoencryption due to its many properties that are beneficial to this protocol. The security of a geoencryption system resides in the geotag. In order to evaluate the security level of geoencryption system, we develop a mathematical framework to measure the information content of Loran location-based parameters.

Reliable Location-Based Services from Radio Navigation Systems

Loran is a radio-based navigation system originally designed for naval applications. We show that Loran-C’s high-power and high repeatable accuracy are fantastic for security applications. First, we show how to derive a precise location tag—with a sensitivity of about 20 meters—that is difficult to project to an exact location. A device can use our location tag to block or allow certain actions, without knowing its precise location. To ensure that our tag is reproducible we make use of fuzzy extractors, a mechanism originally designed for biometric authentication. We build a fuzzy extractor specifically designed for radio-type errors and give experimental evidence to show its effectiveness. Second, we show that our location tag is difficult to predict from a distance. For example, an observer cannot predict the location tag inside a guarded data center from a few hundreds of meters away. As an application, consider a location-aware disk drive that will only work inside the data center. An attacker who steals the device and is capable of spoofing Loran-C signals, still cannot make the device work since he does not know what location tag to spoof. We provide experimental data supporting our unpredictability claim.