1,721,165 research outputs found
Integrated optical components for quantum key distribution
Full text linkThe security of current public key cryptosystems, such as RSA, depends on the difficulty of computing certain functions known as trapdoor functions. However, as computational resources become more abundant with the fast development of super- and quantum computers, relying on such methods for communication security becomes risky. Quantum key distribution (QKD), is a potential solution that can allow theoretically secure key exchange for future communications. Chip-scale integration of this solution for securing communication of embedded systems and hand held devices demands miniaturizing the optical components that are used in typical QKD boxes, hence reducing its size and cost. The aim of the work in this thesis is firstly investigating novel approaches to realising integrable single photon sources and detectors for applications such as QKD, and secondly proposing a chip-scale integrated QKD system with efficient and optimised optical components. In the first part of the thesis, a model for coupling 2D material emitters to rod-type photonic cavities is studied for room temperature single photon sources. Our investigated approach allows better coupling between the emitter and the cavity modes than conventional methods, while increasing light collection ratio. In the second part, site-controlled growth of semiconductor III-V nanowires on Si for photodetection applications is achieved by fabricating the sites using electron-beam lithography and wet etching. Studies were also carried out to investigate the effect of the wafer’s growth temperature on the nanowire formation. Finally, a model was proposed for realising a chip-scale QKD system using photonic crystals as a photonic circuit platform. The work involves increasing the Q-factor of the cavity single photon source, increasing cavity waveguide coupling, reducing losses in beam splitters and out-couplers. A final model of a chip-scale QKD system which involves the optimised components is proposed at the end of the thesis
SonarSnoop: active acoustic side-channel attacks
No full textWe report the first active acoustic side-channel attack. Speakers are used to emit human inaudible acoustic signals and the echo is recorded via microphones, turning the acoustic system of a smart phone into a sonar system. The echo signal can be used to profile user interaction with the device. For example, a victim's finger movements can be inferred to steal Android phone unlock patterns. In our empirical study, the number of candidate unlock patterns that an attacker must try to authenticate herself to a Samsung S4 Android phone can be reduced by up to 70% using this novel acoustic side-channel. Our approach can be easily applied to other application scenarios and device types. Overall, our work highlights a new family of security threats
Smart Speaker Privacy Control - Acoustic Tagging for Personal Voice Assistants
Full text linkPersonal Voice Assistants (PVAs) such as the Siri, Amazon Echo and Google Home are now commonplace. PVAs continuously monitor conversations which may be transported to a cloud back end where they are stored, processed and maybe even passed on to other service providers. At present, a user has little control over this process. He is unable to control the recording behaviour of surrounding PVAs, is unable to signal his privacy requirements to back-end systems and is unable to track conversation recordings. In this paper we explore techniques for embedding additional information into acoustic signals processed by PVAs. A user employs a tagging device which emits an acoustic signal when PVA activity is assumed. Any active PVA will embed this tag in the recorded audio stream. The tag may signal a cooperating PVA or back-end system that a user has not given a recording consent. The tag may also be used to trace when and where a recording was taken. In this paper we discuss different tagging techniques and application scenarios. We describe the implementation of a prototype tagging device based on PocketSphinx. Using the popular PVA Google Home Mini we demonstrate that the device can tag conversations and that the tagging signal can be retrieved from conversations stored in the Google back-end system
Towards Reactive Acoustic Jamming for Personal Voice Assistants
Full text linkPersonal Voice Assistants (PVAs) such as the Amazon Echo are com- monplace and it is now likely to always be in range of at least one PVA. Although the devices are very helpful they are also continuously monitoring conversations. When a PVA detects a wake word, the immediately following conversation is recorded and transported to a cloud system for further analysis. In this paper we investigate an active protection mechanism against PVAs: reactive jamming. A Protection Jamming Device (PJD) is employed to observe conversations. Upon detection of a PVA wake word the PJD emits an acoustic jamming signal. The PJD must detect the wake word faster than the PVA such that the jamming signal still prevents wake word detection by the PVA. The paper presents an evaluation of the e ectiveness of di erent jamming signals. We quantify the impact of jamming signal and wake word overlap on jamming success. Furthermore, we quantify the jamming false positive rate in depen- dence of the overlap. Our evaluation shows that a 100% jamming success can be achieved with an overlap of at least 60% with a negligible false positive rate. Thus, reactive jamming of PVAs is feasible without creating a system perceived as a noise nuisance
Wireless Sensor Networks, 6th European Conference, EWSN 2009, Cork, Ireland, February 11-13, 2009. Proceedings
No full text
Optically Interrogated Unique Object with Simulation Attack Prevention
Full text linkA Unique Object (UNO) is a physical object with unique characteristics that can be measured externally. The usually analogue measurement can be converted into a digital representation - a fingerprint - which uniquely identifies the object. For practical applications it is necessary that measurements can be performed without the need of specialist equipment or complex measurement setup. Furthermore, a UNO should be able to defeat simulation attacks; an attacker may replace the UNO with a device or system that produces the expected measurement. Recently a novel type of UNOs based on Quantum Dots (QDs) and exhibiting unique photo-luminescence properties has been proposed. The uniqueness of these UNOs is based on quantum effects that can be interrogated using a light source and a camera. The so called Quantum Confinement UNO (QCUNO) responds uniquely to different light excitation levels which is exploited for simulation attack protection, as opposed to focusing on features too small to reproduce and therefore difficult to measure. In this paper we describe methods for extraction of fingerprints from the QCUNO. We evaluate our proposed methods using 46 UNOs in a controlled setup. Focus of the evaluation are entropy, error resilience and the ability to detect simulation attacks
Firewalls and their Impact on Multimedia Systems : Panel Discussion "Security Firewalls and their Impact on Multimedia Systems"
No full textFirewall-Architekturen für Multimedia-Applikationen
No full textIn this thesis on Firewall Architectures for Multimedia Applications solutions are developed and discussed that enable the usage of multimedia applications in network environments where firewalls are employed. The provided solutions cover optimizations of existing firewall architectures as well as the development of new mechanisms to implement firewall architectures. Within a global networked environment, security aspects become more and more important and access control at network borders is considered to be essential. For this purpose firewalls which provide access control and auditing at the border between open and private networks or administrative domains are used. As integral part of the network infrastructure they are strongly affected by the development and deployment of new communication paradigms and applications. Currently we experience a very fast rise in the use of multimedia applications which differ in many aspects from "traditional" applications. Existing firewalls are not able to support this new types of applications in an efficient and secure manner. This thesis identifies and classifies the existing problem areas. It can be deduced from this classification that a modification and extension of existing firewall architectures are suitable methods to solve these problems. In the thesis it is shown that an appropriate firewall architecture has to apply the design pattern "Separation of Signalling and Media Flows". A new architectural model is introduced which can be used to structure firewall architectures regarding the criterias necessary to support multimedia applications. Thus, it is possible to investigate different categories of architectures and it is shown that the category of distributed firewalls fits best to support multimedia applications. This model also allows to identify which elements are missing or have to be optimized to build distributed firewalls. An important element of a distributed firewall is the communication between the different firewall components. Instead of developing a new protocol - as currently proposed in the standardization bodies - it is shown that the existing and approved Resource Reservation Protocol (RSVP) can be used for this purpose. It is shown by an implementation that RSVP can be used in practice. Another important element used in firewall architectures is the signalling element. State of the art methods used for integration of the signalling element within a scenario cannot be used in multimedia scenarios. It is shown in the thesis that the necessary integration mechanisms have to be deduced from integration mechanisms used for multimedia infrastructure components. On the basis of an implementation it is shown that this approach is also feasible in practice. Within the thesis the performance of firewall architectures is investigated. The parameters which limit the performance of a multimedia firewall are identified. It is shown how these parameters have to be taken into account to optimize a firewall for specific performance requirements. Measurements are performed to show that the proposed changes in firewall architectures are optimal regarding the performance. Distributed firewalls that use the design pattern "Separation of Signalling and Media Flows" have to be used to optimize the performance of a multimedia firewall. Within the thesis several tools had been developed to show the feasibility of the given statements which can also be used for other purposes not regarded in this thesis. The tool KOMtraffgen can be used for performance measurements as well as to determine performance values of components used in the communication path of multimedia applications. The tool KOMproxyd can be used to build firewall architectures for multimedia applications. It is currently used within the video conference service of the Deutsches Forschungsnetz (DFN)
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