• Monica Mitra
• P. K. Bharti

Cloud computing is sharing various computing resources rather than having local servers or personal devices to handle applications over the internet. To share these resources cloud provides three services namely, Software as a Service, Platform as a service and Infrastructure as a service. The deployment models of cloud include Private cloud, Public cloud and Hybrid cloud. Due to the benefits of cloud computing, there is a lot of data stored on cloud and multiple requests come for resources, hence it is customary to enforce adequate protection to the data in Cloud. Factors responsible for cloud security are Confidentiality, Privacy, Integrity and Availability of the data. The Multi-Cloud or ‘Cloud–of–Clouds’ has emerged as key solution to various obstacles faced in a single cloud platform. Multi cloud is highly needed due to the fact that sensitive data could not be entrusted to a single cloud and also to avoid dependency on just one cloud provider in risk of some failure. Hence switching the cloud computing from single cloud to multi-cloud is mandatory to fulfill data security. Existing Multi-cloud types include Intra Cloud, Hybrid cloud, Federated Clouds and Multi-Cloud. There are several approaches available to enhance security in multi-clouds. One of the methods is where data to be stored is split into various blocks and distributed among different cloud storage providers in a redundant way. Other methods include Homomorphic encryption, Attribute based Encryption (ABE), building a Multi-Cloud Database Model (MCDB) etc. This paper analyzes various research activities and methods for enhancing the security and safety in the Multi-Clouds.

Cloud Computing, Cloud Service Provider, Cloud Security, Data Privacy, Data Availability, Encryption, Multi-Cloud

"Enhancing the Security for Dynamic Data Sharing in Multi-Cloud Environment", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.9, Issue 11, page no.g45-g50, November-2022, Available :http://www.jetir.org/papers/JETIR2211640.pdf

"Enhancing the Security for Dynamic Data Sharing in Multi-Cloud Environment", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.9, Issue 11, page no. ppg45-g50, November-2022, Available at : http://www.jetir.org/papers/JETIR2211640.pdf