The advent of cloud computing has dramatically changed the IT scene, as it offers cost savings and improvements to major operations. Nevertheless, the major obstacle relies on the effort on how to secure sensitive data files that are outsourced to the cloud environment. To ensure confidentiality, the sensitive data are usually encrypted prior to being outsourced. Nevertheless, effective data utilization remains a challenging task and there is a clear need for a secure and efficient searching mechanism over the encrypted data in the cloud, to increase the us-ability of the secure cloud environment. Unfortunately, existing work in the area of secure searching in the outsourcing scenario usually incur high computational complexity, which makes the approach impractical. In this paper, we take one step ahead by proposing an efficient keyword search scheme for cloud computing. Our solution is very lightweight, and it enables efficient multi-user keyword search over outsourced data files in the cloud environment, without leaking any private information about both the data owner and users in the search query. We formally define the security requirements and prove that our scheme is secure under a simple assumption in the standard model.