Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction. Cloud computing recently emerged as a promising solution to information technology (IT) management. IT managers look to cloud computing as a means to maintain a flexible and scalable IT infrastructure that enables business agility. As much as the technological benefits, cloud computing also has risks involved. In this paper Cloud Computing security challenges will be discussed and proposed many new recommendations to increase security and trust also maintaining privacy.