Abstract
Cloud computing is often referred to as the technology of the decade. Current Cloud systems present critical limitations to protecting users' data confidentiality. This survey presents a review of the three essential data security attributes in the context of Cloud computing, namely, availability, integrity and confidentiality. It explores numerous research efforts to enhance the security and privacy of data in the Cloud with a focus on maintaining data confidentiality. Recent solutions are critically analysed, and their advantages and limitations are discussed. The paper finishes with a discussion on the future research opportunities and challenges on data confidentiality in the Cloud.