Implementing secure data access control for multi-authority cloud storage system using Ciphertext Policy-Attribute based encryption
S. Vijaya Lekshmi, M. Revathi · 2014
Data access control is an effective way to ensure the data security in the cloud. However, due to data outsourcing and untrusted cloud servers, the data access control becomes a challenging issue in cloud storage systems. In a multi-authority Attribute Based Encryption scheme, multiple attribute-authorities monitor different sets of attributes and issue corresponding decryption keys to users, and encryptors can require that a user obtain keys for appropriate attributes from each authority before decrypting a message. Ciphertext-Policy Attribute Based Encryption (CP-ABE) is a promising cryptographic primitive for fine-grained access control of shared data. In CP-ABE, each user is associated with a set of attributes and data are encrypted with access structures on attributes. A user is able to decrypt a ciphertext if and only if his attributes satisfy the ciphertext access structure. An important issue of attribute revocation is cumbersome for CP-ABE schemes. This challenging issue is considering by more practical scenarios in which semi-trustable on-line proxy servers are available. The proposed solution enables the multi-authority to revoke user attributes with minimal effort. This is achieve by uniquely integrating the technique of proxy re-encryption with CP-ABE, and enable the authority to delegate most of laborious tasks to proxy servers. The proposed scheme is provably secure against chosen ciphertext attacks.