© 2015 IEEE. Due to the proliferation of high-speed mobile networks and powerful smartphones featuring on-board GPS and multi-modal sensors devices, urban sensing has recently emerged as a novel computing paradigm for enabling future smart cities. However, users' privacy protection represents currently one of the biggest challenges which can significantly impact the engagement of people and the widespread adoption of such applications. In this paper, we propose a novel trajectory privacy-preserving architecture for urban sensing and traffic control applications. We show that our approach maintains the privacy of users while reducing the performance overhead of cryptographic computations. We further demonstrate that our solution is simple, scalable, and is robust against external attacks in maintaining data privacy and confidentiality of the users.