8/30/2023 0 Comments Ultrasonic listening device![]() ![]() ![]() InĢ016 Asia-Pacific International Symposium onĮlectromagnetic Compatibility (APEMC), Vol. 01.įastest mobile audio engine for games, VR, music andĮnergy detection of unknown deterministic signals.Ultrasonic Hearing & Echo Location Smartphones based on compromising emanations. Network transmission of hidden data using On the Privacy and Security of the Ultrasound ACM,Ĭreepy Ad Company Says It Will Stop Eavesdropping On Information Hiding and Multimedia Security. On characterizing and measuring out-of-band covertĬhannels. On Acoustic Covert Channels Between Air-Gapped (EuroS&P), 2017 IEEE European Symposium on. Privacy threats through ultrasonic side channels on This project was funded by the netidee initiative of the Internet Foundation Austria under grant no. 17. The authors thank Kevin Pirner and Peter Kopciak for their contributions. Ultrasonic noise: (a) ultrasonic messages in presence of noise (b) noise removal by spectral normalization. The detector has only one parameter to tune (threshold t) which has shown to be rather insensitive (0.5 yielded good results in all experiments so far). This avoids false detections and makes the system more robust. Additionally, we use a running median filter to track if changes in the spectrum sustain over longer time. We apply a simple thresholding (threshold t) to the KL divergence to detect changes in the ultrasonic spectrum. The KL divergence indicates if both samples stem from the same distribution (value range 0 to 1). To test for detections, we compute the Kullback-Leibler (KL) divergence between the background model and the spectral distribution of the incoming signal. Once the buffer is full, we compute the median of the spectral frequency distribution over time to obtain a robust estimate of the ambient sound distribution. Each input frame is stored in a cyclic buffer of a few seconds duration (e.g. After normalization, most ambient noise is removed and the transmission frequencies become more salient, see Figure 2(b). ![]() We normalize the spectrum to remove broad-band noise, which frequently occurs in the near-ultrasound band. ![]() We first remove audible frequencies with a high-pass filter and compute the short-time FFT spectrum. In more detail, the signal detection is performed as follows. We model the spectral distribution in the ultrasound band statistically, build (and continuously update) a robust background model of the local surrounding and use this model to detect ultrasonic activity. Recently, the threat has been recognized by researchers and first ideas for defensive mechanisms have been proposed (Mavroudis et al., 2017). Furthermore, research has shown that ultrasonic data exchange can be used as covert channel to exfiltrate and leak information from devices (DoĮt al., 2015 Carrara and Adams, 2015a SunĮt al., 2016). The study identified 234 applications with ultrasonic tracking functionality where the most popular had between 1 and 5 million downloads. A recent study has investigated the potential risk of ultrasonic side channels by systematically investigating more than 1.3 million mobile applications for ultrasonic tracking capabilities (ArpĮt al., 2017). In 2015 already, the company Silverpush claimed to be tracking 18M devices with their ultrasonic technology (Kopfstein, 2015). Data over audio can be used as a side channel to track users and their behavior across different devices without their knowledge (Waddell, 2015). This technology, also called data over audio, enables effective near field communication capabilities but also opens up a number of security and privacy concerns. Several recently introduced technologies use (almost) inaudible near-ultrasonic signals (18-22kHz) to exchange information across the auditory channel through the loudspeakers and microphones of mobile devices (Google, 2018 Lisnr, 2018 Shopkick, 2018). Mobile multimedia data (especially audio) can be used aside from entertainment purposes also for near field communication (NFC). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |