Numerous blockchain simulators have been proposed to allow researchers to simulate mainstream blockchains. However, we have not yet found a testbed that enables researchers to develop and evaluate their new consensus algorithms or new protocols for blockchain sharding systems. To fill this gap, we developed BlockEmulator, which is designed as an experimental platform, particularly for emulating blockchain sharding mechanisms. BlockEmulator adopts a lightweight blockchain architecture so developers can only focus on implementing their new protocols or mechanisms. Using layered modules and useful programming interfaces offered by BlockEmulator, researchers can implement a new protocol with minimum effort. Through experiments, we test various functionalities of BlockEmulator in two steps. First, we prove the correctness of the emulation results yielded by BlockEmulator by comparing the theoretical analysis with the observed experiment results. Second, other experimental results demonstrate that BlockEmulator can facilitate measuring a series of metrics, including throughput, transaction confirmation latency, cross-shard transaction ratio, the queuing status of transaction pools, workload distribution across blockchain shards, etc. We have made BlockEmulator open-source in Github.

Scalability trilemma is a classical research topic in the area of blockchains. To defeat such trilemma, many previous solutions have been proposed. However, none of those previous solutions can break such scalability trilemma. In this paper, we present a new Layer2 blockchain called W3Chain, which is promising to deliver high transactions per second (TPS) while defeating the scalability trilemma of a public blockchain. To enable the claimed performance, we particularly design our W3Chain by decoupling the correctness of the blockchain into two parts and adopting several crucial technical issues such as the reconfiguration of committees, the design of query APIs, and the handling of cross-shard transactions. We also propose a Time-Beacon Chain (TBChain) to record pivotal data of W3Chain. To show the correctness and safety features, we rigorously analyze multiple properties of W3Chain, including decentralization, scalability, and security under typical attacks. Finally, we conduct extensive simulations using Ethereum's historical transactions to examine the proposed W3Chain. The evaluation results show that our W3Chain can achieve a TPS as high as 10K+, and much lower transaction confirmation latency compared with Ethereum.

In isolated network domains, global trustworthiness (e.g., consistent network view) is critical to the multiple-domain business partners who aim to perform the trusted corporations depending on each isolated network view. However, to achieve such global trustworthiness across distributed network domains is a challenge. This is because when multiple-domain partners are required to exchange their local domain views with each other, it is difficult to ensure the data trustworthiness among them. In addition, the isolated domain view in each partner is prone to be destroyed by malicious falsification attacks. To this end, we propose a blockchain-based approach that can ensure the trustworthiness among multiple-party domains. In this paper, we mainly present the design and implementation of the proposed trustworthiness-protection system. A cloud-based prototype and a local testbed are developed based on Ethereum. Finally, experimental results demonstrate the effectiveness of the proposed prototype and testbed.