Spatial Crowdsourcing (SC) is a new valuable paradigm, relies on crowd workers to perform a set of spatial-temporal tasks at specific locations. It has garnered attention in collecting and processing social, environmental, and other spatio-temporal data by the contribution of individuals, communities and groups of workers in the physical world. The objective of SC is to outsource a set of spatio-temporal tasks to a set of workers, which requires the workers to be physically traveling to the tasks' locations in order to perform them, i.e., taking photos or collecting real time weather information at pre-specified location. Existing solutions require crowd workers to disclose their precise locations to untrustworthy service providers. Location updates and tracking in spatial crowdsourcing raise several privacy concerns in that malicious parties could snoop on crowd workers' whereabouts. Thus, the crowd workers' privacy could be compromised by disclosing their locations to untrusted and possibly malicious parties. This paper provides a novel framework called Dummies' Centroid (DCentroid), which aims at preserving location privacy for crowd workers in SC. The framework adapts an anonymous communication technique using a dummy based approach to generate dummy locations, i.e. decoy locations, and send their centroid points (pseudolocations) to service providers for processing. This paper theoretically analyzes the DCentroid framework and guarantees the crowd workers' privacy, while preserving the functionality of SC, such as the success rate of task assignments, worker travel distances, and system overhead. Practical experimentation on real-world datasets shows that the DCentroid framework protects the crowd workers' location privacy without affecting the various performance parameters of task assignment. INDEX TERMS DCentroid, location privacy, pseudolocation, spatial crowdsourcing. I. INTRODUCTION T HE term crowdsourcing was first coined by Jeff Howe in 2006 in his article titled "The Rise of Crowdsourcing" in [1]. Since then, it has been a widely used umbrella term and a hot topic in the field of computer science. As stated by Jeff Howe, crowdsourcing is simply clarified as, an open call to an undefined large group of people to take a job that was traditionally performed by a designated agent (usually an employee) [2]. Typically, plenty of people can easily participate in crowdsourcing since it happens online such as Amazon Mechanical Turk (AMT) [3]. Those people can complete any desired task posted by corporations or individuals based on their own knowledge, usually for a small amount of money. With the significant growth of crowdsourcing, the area of Spatial Crowdsourcing (SC) has recently been a popular research topic. SC is a platform for performing spatial-temporal tasks that requires crowd workers to physically travel to the locations of the tasks to perform them. Typically, the tasks submitted by a requester to a centralized spatial crowdsourcing server (SC-server) that act as a speculator between the request...