The ability to use Software Defined Radio (SDR) in the civilian mobile applications will make it possible for the next generation of mobile devices to handle multi-standard personal wireless devices and ubiquitous wireless devices. The original military standard created many beneficial characteristics for SDR, but resulted in a number of disadvantages as well. Many challenges in commercializing SDR are still the subject of interest in the software radio research community. Four main issues that have been already addressed are performance, size, weight, and power. This investigation presents an in-depth study of SDR inter-components communications in terms of total link delay related to the number of components and packet sizes in systems based on Software Communication Architecture (SCA). The study is based on the investigation of the controlled environment platform. Results suggest that the total link delay does not linearly increase with the number of components and the packet sizes. The closed form expression of the delay was modeled using a logistic function in terms of the number of components and packet sizes. The model performed well when the number of components was large. Based upon the mobility applications, energy consumption has become one of the most crucial limitations. SDR will not only provide flexibility of multi-protocol support, but this desirable feature will also bring a choice of mobile protocols. Having such a variety of choices available creates a problem in the selection of the most appropriate protocol to transmit. An investigation in a real-time algorithm to optimize energy efficiency was also performed. Communication energy models were used including switching estimation to develop a waveform selection algorithm. Simulations were performed to validate the concept.

The number of mobile applications (i.e., apps) is rapidly growing, as the mobile computing becomes an integral part of the modern user experience. Malicious apps have infiltrated open marketplaces for mobile platforms. These malicious apps can exfiltrate user's private data, abuse of system resources, or disrupting regular services. Despite the recent advances on mobile security, the problem of detecting vulnerable and malicious mobile apps with high detection accuracy remains an open problem. In this thesis, we address the problem of Android security by presenting a new quantitative program analysis framework for security vetting of Android apps. We first introduce a highly accurate proactive detection solution for detecting individual malicious apps. Our approach enforces benign property as opposed of chasing malware signatures, and uses one complex feature rather than multi-feature as in the existing malware detection methods. In particular, we statically extract a data-flow feature on how user inputs trigger sensitive critical operations, a property referred to as the user-trigger dependence. This feature is extracted through nontrivial Android-specific static program analysis, which can be used in various quantitative analytical methods. Our evaluation on thousands of malicious apps and free popular apps gives a detection accuracy (2% false negative rate and false positive rate) that is better than, or at least competitive against, the state-of-the-art. Furthermore, our method discovers new malicious apps available in the Google Play store that have not been previously detected by anti-virus scanning tools. Second, we present a new app collusion detection approach and algorithms to analyze pairs or groups of communicating apps. App collusion is a new technique utilized by the attackers to evade standard detection. It is a new threat where two or more apps, appearing benign, communicate to perform malicious task. Most of the existing solutions assume the attack model of a stand-alone malicious app, and hence cannot detect app collusion. We first demonstrate experimental evidence on the technical challenges associated with detecting app collusion. Then, we address these challenges by introducing a scalable and an in-depth cross-app static flow analysis approach to identify the risk level associated with communicating apps. Our approach statically analyzes the sensitivity and the context of each inter-app communication with low analysis complexity, and defines fine-grained security policies for the inter-app communication risk detection. Our evaluation results on thousands of free popular apps indicate that our technique is effective. It generates four times fewer false positives compared to the state-of-the-art collusion-detection solution, enhancing the detection capability. The advantages of our inter-app communication analysis approach are the analysis scalability with low complexity, and the substantially improved detection accuracy compared to the state-of-the-art solution. These types of proactive defenses solutions allow defenders to stay proactive when defending against constantly evolving malware threats. / Ph. D.