# Multi-Authority Revocable Access Control Method Based on CP-ABE in NDN
## 1 Introduction  
With the continuous emergence of big data, artificial intelligence, Internet of Things Plus, cloud computing, and other technologies, there are a variety of content-oriented networking applications on the Internet [1; 2]. As long as the content is secure and reliable, users are increasingly interested in using and accessing web content, and users do not care who sends the content. The increasing use of peer-to-peer (P2P) in content delivery networks (CDN) proves this situation [3]. As content distribution increases, the host-centric model-based Internet architecture is difficult to integrate new consumption methods and mobility needs. This situation has inspired experts to create other methods to disseminate content [4; 5]. Therefore, the researchers created an Information Center Network (ICN). ICN connects content consumers directly with content by content name. In this way, the content consumer does not need to identify the address of the content owner, but only the reliable copy of the content. Content owners publish content and store it on the network [6]. This design enables content to be delivered to consumers effectively. There is an advantage in retrieving content and content sharing and distribution, but because content and content publishers are decoupled, data owners cannot protect the privacy and security of data as much as managing local data. Traditional public key cryptosystems only support \"one-to-one\" encryption and lack flexible access control strategies. This poses a huge challenge to security issues during content caching and retrieval. Therefore, a mechanism to ensure data confidentiality should be adopted [7]. To ensure data security, Named Data Network (NDN) networks need to introduce access control methods. However, in the NDN cachesystem, the NDN routing node cannot be completely trusted, because the NDN routing node may conspire with other users to decrypt the content of the data. In order to realize the secure and effective access control effect on NDN network data, we adopt a ciphertext policy attribute-based encryption method (CP-ABE). CP-ABE has the characteristics of flexibility, one-to-many, rich attribute expression, and small granularity in encryption, which is suitable for content distribution and sharing in the NDN environment. The existing ciphertext-based attribute-based encryption scheme is only applicable to the case where the distribution of user attributes and keys belongs to the same organization, but the user attributes may be stored in different cloud storage servers. In the actual application environment, attribute revocation, user permission change, etc., may occur, so implementing data security sharing and implementing attribute revocation on multiple servers becomes an urgent problem to be solved.  
Our contributions can be summarized as follows.  
We propose a CP-ABE-based multi-authority revocable access control method. This method constructs a proxy-assisted access control scheme to achieve secure and effective access control of data in the NDN network. We design an effective user and attribute revocation method, and ensure forward security and backward security to prevent collusion attacks. In addition, from a comparative analysis of performance and safety, we show that our scheme is safer and more efficient than other schemes.