Cloud computing has increasingly become a new model in the world of computing, and more businesses are moving to the cloud. As a cost-effective and time-efficient way to develop new applications and services, service aggregation in cloud computing empowers all service providers and consumers and creates tremendous opportunities in various industry sectors. However, it also poses various challenges to the privacy of personal information as well as the confidentiality of business and governmental information. The full benefits of service aggregation in cloud computing would only be enjoyed if the privacy concerns are addressed properly. In this paper, we investigate the privacy issues in service aggregation in a cloud environment and propose a privacy preserving protocol that is suitable for this environment. To demonstrate the security of our system, we construct a security game called IND-P3SAC-CPA and prove the security of the protocol accordingly. Our protocol has a distinct property that allows any service provider to obtain only the queried data under its conspiracy with the cloud. Additionally, the efficiency and various extensions are also discussed. 468 P. WANG ET AL. cut down on the resource by not leasing it further when the demand has reduced. Furthermore, cloud computing makes it possible for businesses to relocate their information technology management and maintenance outside of their organizations and empowers them to redirect resources toward core functions and competencies [2]. Therefore, it is clear that the trend forces companies to move to the cloud accordingly.A character of the cloud, uncoupling computing tools from physical location, enables users to access data and systems regardless of geographical locations or available media. This encourages businesses to adopt service aggregation ‡ as a cost-effective and time-efficient way to develop new applications and services. Service aggregation in cloud computing supports on-the-fly discovery, aggregation, deployment and provision of services, and realizes the on-demand interaction among consumers, cloud providers, service aggregators, and service providers. Therefore, it is empowering all service providers and consumers and creating tremendous opportunities in various industry sectors and maximizing profitability for its users.Service aggregation is associated with methods and tools that create composite services and their lifecycle management including alignment of privacy policies, security, transaction management, quality of service, and other elements of service provision. In the Internet, the service providers are geographically distributed. A service aggregator manages the services requested by a client. The aggregated service could be one or multiple services in terms of the client's requirement. In general, the service aggregator is the only entity that is visible to the client. To obtain a suitable service, a client needs to register with the aggregator. For getting a service, a client only needs to contact the aggregator, who in turn c...