Securing Outsourced Data on Cloud Using ElGamal Method

Abstract

Cloud computing is a popular technology which grants storing and accessing data over Internet instead of storing it on local machine's hard drive. Cloud empowers users to store their data on cloud without dreading about its accuracy and reliability. However storing data on cloud forces certain security challenges. Outsourcing data in cloud result in data owners losing their physical control over the data. Certain Cloud Service Providers (CSPs) may work unscrupulously with the cloud user's data, they may sneak the data from cloud and sell it to third parties in order to earn profit. In this manner despite the fact that outsourcing data on cloud is economical and decreases long duration storage and maintenance complexity, there is minimum assurance of data integrity, protection, security and availability on cloud servers. Various arrangements have been prescribed to explain the security issues in cloud. This paper concentrates on the integrity verification methodology for outsourced data. The proposed scheme combines the encrypting mechanism along with integrity verification strategy. The encrypting scheme utilized here is public key cryptographic algorithm like ElGamal and SHA-256 hash function is utilized for ensuring data storage correctness on untrusted server.