An Authentication Technique for Accessing De-Duplicated Data From Private Cloud Using One Time Password

Introduction

Cloud computing technology is used to store enormous amount of data and appear to be a virtual resource to the users. It is dynamic and can be easily accessed from anywhere provided with internet. It encapsulates the platform and execution details from the user. Instead of using costly hardware components, cloud service is comparatively cheap. It is extensible, scalable and updated with ease. Ex: If the user currently has 2GB of space and is in need of further storage space (Li, 2013; Itani, 2009), he can expand it easily. Private cloud provides more security (Mohan, 2013; Popović, 2010; Prakash, 2012) with less storage space. It can be accessed easily. It is suitable to use within the organisation. Data (Annamalai, 2015) can be accessed based on privileges. The keys for the files stored in public cloud are usually stored in private cloud. On contrary, public cloud provides data storage with less security. It is mostly concerned with the private cloud. To secure the data from losing its confidentiality, privileges (Prakash, 2015; Annamalai, 2015) are given to the files, so that only specific people can access the file. Privileges can be given both the types of cloud service (Saravanakumar, 2012). Authorization to the cloud is provided based on the credentials stored in the database during registration with the cloud. De-duplication is a data compression technique used to eliminate the redundant copies in the cloud enhancing (Mell, 2009; Khan, 2016) the storage capacity. It is done at both file level and block level. In file level, it eliminates the duplicated files and at block level redundant blocks in the file are eliminated in non-identical files. The file attributes like size, content and type are checked. Privacy concerns are present due to insider and outsider attacks. Data are encrypted (Corena, 2012; Ryan, 2011) for security (Pearson, 2013; Subashini, 2011) reasons. In traditional encryption, when the same file is uploaded by different people different cipher texts are created for each individual. This makes de-duplication difficult. In convergent encryption, a convergent key is generated by calculating the cryptographic hash value of the file. This key is used to encrypt or decrypt the file. Keys are present with the user and the cipher texts thus generated are stored in the cloud. Here the cipher text produced for identical copies of file will be same and helps in de-duplication. Proof of ownership is provided to the files to ensure the user holds the file in spite of duplicate copies. When convergent encryption is used de-duplication of cipher text is possible and proof of ownership helps to enhance confidentiality. The de-duplication systems based on this fail to provide duplicate check with privileges. Issues arise when de-duplication with privileges are tried to be implemented at same time.