Published Paper Details:

In cloud, an effective way to ensure security is using Data Access Control. But, data access control becomes a very challenging issue in cloud storage systems due to untrusted cloud servers and data outsourcing. To overcome this problem multi-authority Attribute Based Encryption is employed. In this different sets of attributes along with the corresponding decryption keys are issued to users by the attribute authorities. Ciphertext Policy Attribute Based Encryption (CP-ABE) is a promising cryptographic technique based on these attributes. A user is able to decrypt a ciphertext if and only if his attributes satisfy the ciphertext access structure in which each user is associated with a set of attributes and the data is encrypted using access structures. However, attribute revocation becomes cumbersome for this scheme. The proposed solution enables the multi-authority to revoke user attributes with minimal effort. By uniquely integrating the technique of proxy re-encryption and CP-ABE, attributes can be revoked with minimal effort. This enables the authority to delegate the most laborious tasks to proxy servers.