IOSR Journal of Computer Engineering (IOSR-JCE) e-ISSN: 2278-0661, p-ISSN: 2278-8727 PP 65-67 www.iosrjournals.org Innovation in engineering science and technology (NCIEST-2015) 65 | Page JSPM’S Rajarshi Shahu College Of Engineering,Pune-33,Maharashtra ,India Survey On Techniques for data integrity verification in cloud storage Miss.Prachiti M.Karandikar 1 , Dr. Pradeep K. Deshmukh 2 1 (Computer Department, RSCOE, Pune/ savitribai phule pune university, India) 2 (Computer Department, RSCOE, Pune/ savitribai phule pune university, India) Abstract: Cloud computing is becoming very popular. Users are choosing cloud as repository for their data. The data in the cloud should be accessible, correct, consistent and high quality. While considering cloud as storage data security and integrity of stored data is burning issue. When users store their data on cloud there is a risk of modification or updation of data. Many researchers had worked and proposed algorithms to solve this issue. This survey paper focuses on two core techniques of proof of storage (POS) that are Proof of data Possession (PDP) and Proof of Retrievability (PoR). Both the techniques are used to ensure the cloud client about integrity of data storage on cloud. Keywords: cloud computing, data security, data integrity, proof of data possession, proof of retrievability, I. Introduction Cloud computing is an emerging technology which provides many services over internet. Many organizations are migrated towards cloud. As cloud is providing multiple characteristics such as on-demand service, location independency, resource pooling and so on. Instead of investing money in new hardware and software and also for the maintaince of resources, users can use servers, storage, applications that are available in cloud. Cloud computing provides you luxury of using all the computer hardware and software from anywhere and at anytime. These softwares and hardwares are not actually installed on your local machine. Few companies provide you services which allow accessing such hardwares/softwares over internet. Users are unaware about where these resources are actually located and how get managed. The information is transparent to end user. Cloud provides ease of access to all resources needed by client. Storage is most important aspect of this era. Cloud storage represents a model in which service provider give a space in their large scale infrastructure to organizations as well as individuals on rent. It is extensional approach of traditional data centers. Cloud provides unlimited storage with reduced deployment cost. It has many advantages over local storage. Cloud server provides facility to store user’s data on a cloud. So users can upload their data on cloud and can access it without any additional burden of time, location, and cost. Many cloud storage service providers such as Google, Microsoft, amazon EC2, and dropbox have attracted users to use cloud storage. Users are enjoying use of these services due to ease of access to their data which is hosted on another infrastructure. Along with these advantages security and integrity of data stored on cloud storage is burning issue. Users need to verify that their data remain as they stored on cloud .Because data stored on cloud can easily be lost or corrupted due to human errors and hardware and software failures. Traditionally entire data was retrieved from cloud and cryptographic techniques, hash values are used for integrity verification. But this is the wastage of cost, computation of user and communication resources. As cloud computing provides many things in terms of “something –as- a- service” e.g. Platform as a service (PAAS), Software as a service (SAAS), user have to registered himself to the cloud server or to the third party which provide the cloud service. So the privacy of the data and security need to be considered. In order to overcome the problem of integrity verification and security of cloud data many schemes are developed under different systems and models. Privacy of the user data and personal information can be provided by the cryptographic function and technology. Two basic approaches are developed by researchers to check integrity of outsourced data called provable data possession (PDP) and Proof of retrievability (PoR). Provable data possession (PDP): PDP techniques are used by clients to check their data that is stored on cloud server. It ensures client that their data is untouched. Client maintains some constant amount of metadata to verify proof. It supports large data sets in widely distributed networks. Proof of retrievability (PoR): In PoR system data storage center must have to give a proof to a data owner (client) that client’s data is intact on storage. Also it allows client to recover his outsourced data. In PoR prover and verifier both doesn’t needed to have knowledge of file F.