# LBFT: An Asynchronous Committee-Based Blockchain Storage Strategy on Zero Trust Model
### Related Work  
**Storage boosting. ** As mentioned before, an increasing amount of data is stored on the blockchain, causing severe storage redundancy, and many solutions have been proposed. Various distributed storage systems have been introduced. Storj and IPFS [10; 11] are popular distributed storage schemes that improve traditional storage systems and obtain better performance. Moreover, some strategies, such as Merkle-Tree, light-node, and lightening networks, are proposed, aiming to decrease the amount of information stored on the chain [12; 13; 14; 15; 16]. Nevertheless, these schemes merely decrease the amount of data that need to be stored in full-replication or the number of nodes of full-replication (i.e., full nodes), which does not fundamentally overturn the full-replication storage strategy. The recently proposed BFT-Store offers a brand new idea that combines erasure coding with the PBFT protocol, enabling each node to store merely a part of the encoded blocks [3]. Soon afterward BFT-Store was proposed, PartitionChain [6] improved its encoding strategy and achieved higher efficiency while also maintaining low storage overheads. Inspired by this exciting innovation, we propose LBFT, which has better robustness and wider applications. In the design of LBFT, we mainly consider improving system performance from three aspects: security model, time assumption of the network, and participants dedicated to decoding. **Traditional security model or zero-trust model. ** In recent decades, the traditional perimeter-based security model was widely used in the world of information security, which contains at least one _trusted_ port and another _untrusted_ port [7]. Nevertheless, in the real world, it is scarcely possible for security professionals to identify which interfaces can be trusted. Worse still, in the position of trust, malicious insiders who have broad access to corporate resources might commit a crime or act insidiously, causing information disclosure and severe economic loss with ease. To address the above and achieve higher-level security, a disruptive model termed the zero-trust model is proposed, focusing on protecting system resources regardless of the location parameters. The elegant work of [17] clarifies the indispensable requirements of implementing a zero-trust model: (1) all network traffic needs to be encrypted regardless of the topological location of the network; (2) access to the system resources is authorized dynamically on a per-connection basis, and it will not automatically permit access to another different resource. On the other side, BFT protocols are the fundamental mechanisms of the consensus on proposed transactions in blockchain systems, enabling untrusted peers to reach an agreement on an eventual output based on their respective inputs against Byzantine nodes [18; 19]. According to different design goals and application scenarios, the BFT protocols are constructed in diverse flavors. **Synchronous or asynchronous BFT protocols. ** According to the time assumption of the system model, the BFT protocols can be divided into three categories: synchronous, partially synchronous, and asynchronous. In the earlier years, considering that the scale of the network is small and the peers are geographically close and well-connected, the designed BFT protocols always have a synchronous time assumption [20]. Dfinity, for instance, is a four-layer synchronous BFT protocol that contains a randomness beacon acting as a verifiable random function (VRF), which produces a stream of consensual outputs [21]. Another well-known synchronous protocol is Sync HotStuff, an intuitive synchronous BFT solution that can achieve consensus with a latency of \(2\Delta\) in time assumption (where \(\Delta\) is the delay upper bound) [22]. With the development of the Internet, the application scenarios of BFT have become more diverse and complicated, so lots of effort are put into relaxing the time assumption.