International Journal of Computer Applications (0975 – 8887) Volume 83 – No 10, December 2013 7 CPDP Scheme to Provide Data Integrity in Multicloud Roshan R. Kolte (M.Tech CSE) RGPV University Bhopal Rahul Deshmukh (Prof.& HOD CSE) RGPV University Bhopal Niraj V. Telrandhe (M.Tech CSE) RTMN University Nagpur ABSTRACT Nowadays, Cloud storage service is a faster profit growth point by providing a position-independent, low -cost platform, comparably scalable for client’s data. The construction of cloud computing environment is based on interfaces and open architecture. It has cloud capable to include multiple internal and external cloud services together to provide high interoperability there can be multiple accounts associated with a single or multiple service providers. so, Security in terms of integrity is main and most important aspect in cloud computing environment. Cooperative Provable data possession (CPDP) is a method for integrity the ensuring of data in storage outsourcing. Therefore, we address the construction of an efficient dynamic audit service and CPDP scheme for distributed cloud storage as well verifying the integrity guarantee of an entrusted and outsourced storage which support the data migration and scalability of service. Keywords Cloud Computing, Cooperative Provable data possession, Data storage, Integrity verification, Multicloud, Proof of retrievability. 1. INTRODUCTION The main purpose of this paper is to provide security in terms of uprightness and availability of client’s data which is stored on cloud. This paper will not put any load on to communication and computation and further, performance guarantee shall also be taken care of by allowing trusted third party to verify the correctness of the cloud data on demand without retrieving a copy of the whole data or introducing additional on-line burden to cloud users Many developments are opening up the period of Cloud Computing, which is Internet-based development and use of computer and Information technology. Suppose the large size of the client’s constrained resource capability and the outsourced electronic data, the center of the problem can be generalized as how can the client find an efficient way to perform periodical integrity verifications without the local copy of data files. Several proposal [1][2][6][7] are proposed to solve the problem. Those proposals focus on achieve the following requirements: retrievability of data, high efficiency, Stateless verification, limitless use of queries and public verification. In general, if one scheme supports private verification, it can possess higher efficiency. 2. MOTIVATION The cloud computing has been seen as the next computing has been seen as the next generation of enterprise Information and Computer Technology infrastructure, Applications, software, as a service and users will also concentrated all the information stored in the cloud data centre, this new data storage model will bring new challenges and new problems. Because the speed of today's data has produced far more than the current availability of storage devices, so there will be more and more data need to be outsource [2]. One of the main and most important and attention issues that is in the cloud computing environment, servers store data with security in terms of integrity verification. For example, storage service providers may order their own interests to hide an error to save the data more seriously, storage service providers in order to save storage space and cost, intentionally remove rarely accessed data, and then who, due to extensive confidential information, limited computing power users and outsourcing Therefore, how to backup data files in the user not the case, found an allowing users to know his information file is stored securely on the server, efficient and securely ways of good information to perform periodically verification, this data storage is cloud computing environment is an essential security issue. 3. CONTRIBUTION Our future harmony has two main contributions: 3.1 Security and Efficiency: We proposed by the CPDP scheme[1][2] is safer to rely on a symmetric and asymmetric key encryption will be clear, efficient in the use of SecretKeyGen and TagGen[5] algorithms. In this key exchange takes place so more secure than symmetric and asymmetric algorithm and every time parameters are generated. However, our arrangement is more efficient than the other techniques. Because it does not require the ratio [8] is more secure because we encrypt data to prevent unauthorized third parties to know its contents and no additional posts on the symbol block, and lots of data encryption in outsourced. 3.2 Public verifiability: To provide public validation we plan a major variation of CPDP scheme. Permit people other than the vendor for information on the server has proved challenge. However, our program than [2] is more efficient because it does not need the information for each block encryption. Framework structure paper for the rest of the paper is as follows. We describe the related work in section IV. Section V describes data integrity for cross cloud environment using CPDP to prove a structure, emphasizing the related parameters and the characteristics of CPDP. We introduce the CPDP can be publicly verifiable information to prove a structure in section VI. In Section VII security analysis of our protocol. However, Section VII is our Conclusion. 4. RELATED WORK Qian Wang et al. [7] introduce a protocol for Integrity verification in Multi cloud that is provided by improving the existing proof of storage models by manipulating the classic Merkle Hash Tree construction for block tag authentication. To support efficient handling of multiple auditing tasks, this paper further explore the technique of bilinear aggregate signature to extend the main result into a multiuser setting,