Multi-authority Attribute Based Encryption with Attribute Revocation

Multi authority attribute based encryption solve a completely trust problem about a single authorization center, make the data owner control fine-grained data and resist collusion attack. But in the practical attribute revocation needs a lot of calculation. Adding the user revocation list into cipher text implements the user revocation. Through agent re-encryption technology, decryption outsourcing technology and time division revocation re-vocation, we implement attributes revocation satisfying the forward security and backward security on the basis of the effective fine grained, meanwhile reducing the computational overhead when the attribute is revoked.

I. Introduction

In recent years, along with the popularization and rapid development of Internet, the amount of information on the Internet is growing fast and exponentially. In order to process these massive data with efficiency, cloud computing technology emerges as the times require. Through the resources (such as hardware, development platform, and I/O service) virtualization, and re-allocate the resources dynamically to the application based on its load, cloud computing achieves better resource utilization. And the cloud storage technology is the foundation of the cloud computing technology. Cloud storage allows users meet the demand of the data they stored without the increasingly high cost of data center management can meet the demand of the data is stored. However, data is beyond the user's control in the cloud storage, so the users are concerned about the security of sensitive data, so the users are unwilling to upload data to the cloud service provider (CSP). Protection of data through the access control is a hot research area in the present study. In order to ensure the security of user's data in cloud storage, the user's data should be encrypted before sending to the outsourced cloud services. Because the cloud service provider is not trustworthy, the user may intentionally or unintentionally divulge the decryption key to cloud services, and the manipulation and management of access policy is completely controlled by the cloud service provider, which have no protection for the sharing of sensitive information and the user's personal information, and it also cannot achieve fine-grained access control for shared data. Ciphertext - Policy Attribute – based on Encryption (CP - ABE) [1] is considered to be one of the most suitable solutions for cloud storage access control technology. In CP - ABE scheme, ciphertext is associated with the access structure; key is associated with the attribute, when and only when user's properties satisfy the access structure, the user can decrypt it. In this scheme, only one authority is responsible for the management of attribute and the distribution of user's private keys, once the authority is destroyed, it may reveal the user's data because the authority can decrypt all data.