# An Accelerating Approach for Blockchain Information Transmission Based on NDN
## 2 Theoretical Support  
In this section, we introduce the related technologies of blockchain and NDN network, which provide theoretical support for our proposed information acceleration strategy. The blockchain technology is a data structure that combines blocks in a chain [10]. It is suitable for storing simple, hierarchical data that can be verified in the system. It is guaranteed by cryptography that the data cannot be falsified or forged [11]. It enablesparticipants to build consensus on the sequence of events and current state of the entire network transaction record [12]. In fact, the blockchain technology is not a new technology, it is a combination of various existing technologies, such as encryption algorithms and P2P transmission, etc. They are combined with database technology to form a new way of recording, delivering, storing, and presenting data [13]. The blockchain technology constructs a P2P self-organizing network using a distributed collective operation method under a distributed peer-to-peer network without a central control point. Through a complex verification mechanism, the blockchain database can maintain integrity, continuity and consistency. Even if some participants falsify, they cannot change the integrity of the blockchain, nor can they tamper with the data in the blockchain. A typical application of blockchain technology is the Bitcoin system. Bitcoin does not have a centralized management center, each node can freely choose to join or leave. All transaction data is opened to all nodes, and each node has the power to verify transactions and generate blocks. Bitcoin uses a proof-of-work mechanism (POW) to achieve consensus among users in the network. In the Bitcoin network, users are divided into three roles, namely miner node, wallet node, and forwarding node. The functions of the three roles will be given in Section 3. With the development of the consumer Internet, TCP/IP networks have gradually exposed their shortcomings in various aspects: reliability, security, and mobility cannot meet the development needs of the network. In 2010, the National Science Foundation proposed the Named Data Networking, a novel networking architecture [5]. The NDN regards content as the dominant entity in the network and adopts a content-based transmission architecture. There are two types of roles in the NDN, consumers and producers. There are two types of packages in the network, namely interest package and data package. The content is identified by the name [14]. If a consumer wants to request certain content, an interest packet with the corresponding name is generated, and it is forwarded through the network to the node where the content is stored. After receiving the interest packet, the node will send the corresponding Data package along the transmission path of the interest packet. Therefore, the NDN uses a receiver-driven and pull mechanism. Different from traditional IP networks, NDN nodes or routers support caching, and each node maintains three modules, which are content storage (CS), pending interest table (PIT), and forwarding information base (FIB) [15]. After receiving the Interest packet, the router first checks whether the corresponding content is cached in the CS, if there is, it will reply directly to the data packet, if not, it will find the PIT, if the PIT has a corresponding entry, it will only record the interface that received the Interest packet without forwarding it If not, forward it according to FIB and forwarding strategy, and add corresponding PIT entry, or discard Interest packet according to relevant information. After receiving the Data packet, the router forwards it according to the information in the corresponding entry in the PIT [16]. Since the content request has been satisfied, the router will delete the corresponding entry in the PIT after forwarding, and determine the content stored in the CS based on the caching strategy and related replacement mechanisms. Obviously, the name occupies a core position in the NDN forwarding process.