Abstract: Cloud Computing has revolutionized businesses and individuals needs by outsourcing computations and storage providing significant cost-effectiveness and flexibility. With its rapid development, the security and privacy are the primary concerns. The homomorphic encryption techniques have provided a good potential in mitigating these issues in recent years. It allows the cloud to perform blind-computations on the encrypted inputs uploaded by the user without prior decryption and return the encrypted results, which can only be decrypted by the user who initiates the proceedings. Thus, clients can rely on the cloud services without compromising the privacy. Some classical, as well as recent practical homomorphic schemes and their algorithms, are discussed in this paper. The main focus is to provide the reader good background knowledge on various schemes for applications in context to practical implementations based on their scope, performance, security and complexity factors.
Keywords: Homomorphic encryption, Cloud Security, FHE schemes, LWE.