Cloud computing is a new paradigm that promises to provide businesses with an IT infrastructure that is flexible, inexpensive and easy to use. Despite such promises, cloud computing has not been adopted at a pace that was expected. Among various reasons that prevent its widespread adoption, the most serious issue that Cloud Computing faces concerns its inability to insure data privacy and confidentiality. The fact that the security challenges faced by the Cloud depend on its deployment model as well as delivery model has further aggravated this problem. Hence we need to develop unique solutions to address security risks at various levels in Cloud Computing. This paper presents a survey on the various types of technologies and architectures that seek to achieve trusted cloud computing at Infrastructure as a Service (IaaS) level. © 2012 IEEE.