© 2013, IJARCSSE All Rights Reserved Page | 381 Volume 3, Issue 6, June 2013 ISSN: 2277 128X International Journal of Advanced Research in Computer Science and Software Engineering Research Paper Available online at: www.ijarcsse.com Data Storage and Data Integrity in Multi-Cloud Storage Priyanka V.Mogre Prof.Girish Agarwal Prof.Pragati Patil Department of CSE, RTMNU Department of CSE, RTMNU Department of CSE, RTMNU Nagpur, India Nagpur, India Nagpur, India Abstract — Cloud computing is used to store data from various resources by the user. It is difficult for the user to store entire data within the system; therefore clouds are formed to store the user data. User can store as much large amount of the data as user wants. This data stored in the cloud must be integrated, the integrity of the data is thus has to be checked and maintain with the help of Trusted third party. Only trusted third party has the authority to check and to maintain the integrity f the data. The main approach of this paper is to check the integrity of the data stored and to maintain the security by using cryptography method. Keywords— Multi-cloud storage, data integrity, cloud privacy, TTP, Cryptography, proofs of retrievability . I. INTRODUCTION In Cloud computing storing and sharing of data is been done via trusted third party. The trusted third party have the authorized key which help to access data between the clouds these helps & maintains privacy via TTP .Data from the various users from various resources are stored in multi-cloud. Accordingly users can login into the cloud and feed the data, user have to buy the clouds as per the requirements on the amount of data to be stored. The only thing was the cloud computing lacks regarding the issues of data integrity, data privacy, and data accessed by unauthorized members. Data integrity: Data integrity refers to maintaining consistency of the data all over the cycle. Data integrity contains protocols for data retention specifying the length of data that can be retained. To achieve data integrity it specifies what can be done with data values when its validity expires. These protocols are consistently and routinely applied to all data entering the system and any enforcement of relaxation will cause error in the data. Strict enforcement of data integrity rules causes the error rates to be lower, resulting in time saved troubleshooting and tracing erroneous data and the errors it causes algorithms. Three types of integrity constraints are an inherent part of the relational data model: entity integrity, referential integrity and domain integrity  Entity integrity: It concerns with concept of Primary keys.  Referential integrity: It concerns the concept f foreign keys.  Domain integrity: It specifies that all the columns in database must be declared upon a defined domain. Cloud storage: Cloud storage is an industry term for managed data storage through hosted network service. The most basic form of cloud storage allows users to upload individual files or folders from their personal computers to a central Internet server. This allows users to make backup copies of files in case their originals are lost. Users can also download their files from the cloud to other devices, and sometimes also enable remote access to the files for other people to share. Modern day cloud storage is base on highly visualized infrastructure and as the same characteristics as cloud computing in terms of elasticity, scalability and multi-tenancy, and is available on Amazon EC2 and ViON capacity service. Fig.a: Architecture of a cloud storage system including control severs and control storage servers. DB Storage DB Storage DB Storage Control node