Physical Layer Watermarking of Binary Phase-shift Keyed Signals Using Standard Gnu Radio Blocks

This thesis discussed the development, implementation, simulation, and testing of a physical layer watermarking method. The method was to use pre-existing GNU Radio building blocks. The main goal of the project was to implement a watermarking method using GNU Radio with the USRP software radios which could also be implemented using standard communications hardware so implementation on SDR systems as well as pre-existing communications systems was possible. Simulations of the physical layer watermarking system were created using a Monte Carlo method. The generation of a probability distribution of phase difference error was appropriate to analyze the expected performance of the DPSK watermarking system developed. Testing was performed in a realistic office environment where interference in the tested frequency band was common. A stationary receiver gathered data from a transmitter at various locations and power levels. The bit error rate of the gathered data was determined to analyze performance. While the testing in a real world environment had a limited range of valid analysis due to limited sampling time and interference, the results were comparable with the simulations. Testing and simulations showed the proposed physical layer watermarking method has the potential to compete with the performance of other authentication focused watermarking methods. In addition, the proposed method could be used to provide a separate, possible secretive, data channel under certain circumstances. An important benefit of the proposed watermarking method is its ability to be implemented in many SDR or traditional communication systems with no hardware modifications.School of Electrical & Computer Engineerin

Physical Layer Watermarking of Direct Sequence Spread Spectrum Signals

Security services and mechanisms in wireless networks have long been studied and developed. However, compared to upper network layers, physical layer security did not play a signicant role in the OSI security model. Thanks to the easier implementation and verication methods brought by the development of software dened radio (SDR) techniques, physical layer security mechanisms have recently drawn increasing interest from researchers. Digital watermarking is one of the popular security techniques that can fully utilize various exclusive characteristics of the physical layer. This thesis proposes a physical layer watermarking technique named Water-marked Direct Sequence Spread Spectrum (DSSS) or WDSSS technique, which embeds authentication information into pseudonoise (PN) sequences of a DSSS system. The design and implementation of the WDSSS prototype system on the GNU Radio/USRP SDR platform is discussed, as well as two watermark embedding methods, the maximized minimum distance method and the sub-sequence method. Theoretical analysis and experimental results on the WDSSS prototype system are presented to evaluate the performances of both the content signal and the watermark signal. Results show that, for the 11-chip PN sequence, increasing articial chip errors has aquantitatively predictable impact on the content signal, requiring 2 dB higher signal-to-noise ratio (SNR) to maintain an acceptable packet error rate (PER) for one additional ipped chip. In terms of the watermark signal, the two embedding methods demonstrated individual advantages in either PER or throughput. The maximized minimum distance method outperforms the sub-sequence embedding method with a 3 dB lower SNR requirement, while the latter provides 400 more throughput than the former with adequate SN

Chaos-based robust method of zero-watermarking for medical signals

The growing use of wireless health data transmission via Internet of Things is significantly beneficial to the healthcare industry for optimal usage of health-related facilities. However, at the same time, the use raises concern of privacy protection. Health-related data are private and should be suitably protected. Several pathologies, such as vocal fold disorders, indicate high risks of prevalence in individuals with voice-related occupations, such as teachers, singers, and lawyers. Approximately, one-third of the world population suffers from the voice-related problems during the life span and unauthorized access to their data can create unavoidable circumstances in their personal and professional lives. In this study, a zero-watermarking method is proposed and implemented to protect the identity of patients who suffer from vocal fold disorders. In the proposed method, an image for a patient's identity is generated and inserted into secret keys instead of a host medical signal. Consequently, imperceptibility is naturally achieved. The locations for the insertion of the watermark are determined by a computation of local binary patterns from the time–frequency spectrum. The spectrum is calculated for low frequencies such that it may not be affected by noise attacks. The experimental results suggest that the proposed method has good performance and robustness against noise, and it is reliable in the recovery of an individual's identity