Shielding of Data Access Control for Multiauthority Cloud Storage Systems using Advanced Encryption Standard

Data access control for multiauthority cloud storage systems (DAC-MACS) is a beneficial way to ensure data security of the cloud storage system. The two main challenging issues of the current cloud storage systems are data outsourcing and untrusted cloud servers. The existing access control policies cannot be applied further as they either produce multiple encrypted copies of the same data or it requires a fully trusted cloud server. In DAC-MACS, there exist multiple attribute authorities which have the capabilities to issue its own attributes independently without any assistance. A new extensive data access control scheme (NEDAC-MACS) with multiple attribute authorities is used which will reduce the workload of a single Attribute Authority (AA). It achieves revocation security by the use of file token specified. Using this scheme the owners data can be accessed by users with the usage of the unique secret key alongside with ciphertext token issued by the admin. The uploaded data can be accessed by the users on the owners approval. In case if the owner uploads some inappropriate content, the users can report or flag to the server which leads to the blocking of the owner by the Certified Authority (CA). After the owner gets blocked after providing access control for the users, the data can be accessed further with the version key issued by the Attribute Authority and updated by admin as a new secret key and download the file. A 256 bit symmetric block cipher Advanced Encryption Standard (AES) encryption standard is used to enhance the security. AES is an assuring method that provides access control of encrypted data and provide more secure attribute revocation.