Today''s technical and legal landscape present formidable challenges to privacy. The disclosure of private data has become commonplace due to carelessness, theft or legal actions. Increasing reliance on network services causes sensitive data to be cached, copied, and archived by third parties, often without users'' knowledge or control. Cloud computing and ubiquitous computing are becoming an integral part of everyday life. The social consequences of this development are profound, and the technological challenges posed by these paradigms are complex and interesting. While the lack of privacy has, in principle, always characterized Internet communications, never before Internet communication has revealed so much about the personal tastes of its users. This is because never before Internet has contained so much personal user data. This work addresses some of the privacy and security issues that arise on line.