A Survey on Security Issues and Security Schemes for Cloud and Multi-Cloud Computing

Cloud computing is typically defined as a type of online computing that believes in sharing computing resources, processing power and storage based on demand rather than dependent on local servers or personal devices to provide such facility. Making „Cloud of Clouds‟ is a recent trend; this mixing combine services from multiple clouds into a single „Cloud of Clouds‟ to avoid the problems of single Cloud Computing, like no guaranty of continuous availability of resources and services. As we are using MULTI-CLOUD facilities now a days because it provides high rate of availability and good performance, but still this Multi-cloud environment have fear of Security issues. To avoid the problem of security issues some prevention and avoidance policies and schemes should be adopted. This paper mainly focuses on many security issues in the “Cloud computing” and “Multi-Cloud computing” and also on security algorithms for Cloud; after surveying the different security algorithms, they have limited benefits and limitations is spotted.