Secure File Storage in Cloud Computing Using Hybrid Cryptography Algorithm Swarna C #1 , Marrynal S. Eastaff *2 #1 PG Scholar, PG Department of IT, Hindusthan College of Arts and Science, Coimbatore, *2 Asst Professor, PG Department of IT, Hindusthan College of Arts and Science, Coimbatore 1 swarna.karishma99@gmail.com , 2 marrynalhindusthan@gmail.com Abstract— In the cloud environment, resources are shared among all of the servers, users and individuals. So it is difficult for the cloud provider to ensure file security. As a result, it is very easy for an intruder to access, misuse and destroy the original form of data. In case of compromise at any cost; entrusting cloud is of no use. A need for “practically strong and infeasible to get attacked” technique becomes vital. The paper presents the file security model which uses the concept of hybrid encryption scheme to meet security needs. In the proposed model, encryption and decryption of files at cloud servers done using blowfish and modified version of RSA. Further, it is tested in cloud environment: Open Nebula. Keywords— Cloud computing, Data Security, Hybrid Cryptosystem I. INTRODUCTION Cloud computing is originated from earlier large-scale distributed computing technology. NIST defines Cloud computing as a model for enabling convenient, on demand network access to a shared pool of configurable computing resources (e.g.,networks, storage, applications and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction”. In Cloud computing, both files and software are not fully contained on the user’s computer. File security concerns arise because both user’s application and program are residing in provider premises. The cloud provider can solve this problem by encrypting the files by using encryption algorithm. This paper presents a file security model to provide an efficient solution for the basic problem of security in cloud environment. In this model, hybrid encryption is used where files are encrypted by blowfish coupled with file splitting and SRNN (modified RSA) is used for the secured communication between users and the servers. A. Data Security Issues Due to openness and multi-tenant characteristics of the cloud, the traditional security mechanisms are no longer suitable for applications and data in cloud. Some of the issues are as following:  Due to dynamic scalability, service and location transparency features of cloud computing model, all kinds of application and data of the cloud platform have no fixed infrastructure and security boundaries. In the event of security breach, it is difficult to isolate a particular resource that has a threat or has been compromised.  According to service delivery models of Cloud computing, resources and cloud services may be owned by multiple providers. As there is a conflict of interest, it is difficult to deploy a unified security measure.  Due to the openness of cloud and sharing virtualized resources by multitenant, user data may be accessed by other unauthorized users. IAE TSD JOURNAL FOR ADVANCE D RE SE ARCH IN APPLIE D SCIE NCE S VOLUME 5, ISSUE 3, MAR/ 2018 ISSN NO: 2394-8442 http:/ / iaetsdjaras.org/ 148