My heartfelt gratitude is due to Prof. Lynn Margaret Batten for her guidance throughout my candidature. It is my great honor to be a student of such a fantastic supervisor, an excellent mentor, and a professional scholar. Her kindness, wisdom, strong passion and determination have strongly shaped my attitudes, behaviors, and habits towards both research and life. I have been enjoying every moment since she introduced me to the topics of data aggregation, querying of public data sets in shared environment, privacy preserving data mining, applied cryptography and mathematics. I am grateful for my parents', sister and brother unconditional love and support throughout my study.