RapidChain is a sharding-based public blockchain protocol designed to overcome the performance and scalability limitations of current blockchain protocols. It achieves this by splitting the processing of transactions among multiple smaller groups of nodes, known as committees, which work in parallel to maximize performance while reducing communication, computation, and storage per node. Unlike existing sharding-based protocols that require a linear amount of communication per transaction, RapidChain introduces an optimal intra-committee consensus algorithm, a novel gossiping protocol for large blocks, and a provably secure reconfiguration mechanism. These innovations enable RapidChain to process over 7,300 transactions per second with an expected confirmation latency of about 8.7 seconds in a network of 4,000 nodes, achieving a time-to-failure of more than 4,500 years. RapidChain's key contributions include: - **Sublinear Communication**: It is the first sharding-based blockchain protocol that requires only a sublinear number of bits exchanged in the network per transaction. - **Byzantine Fault Tolerance**: It is resilient to Byzantine faults from up to a 1/3 fraction of its participants. - **Complete Sharding**: It achieves complete sharding of communication, computation, and storage overhead without assuming any trusted setup. The protocol operates in fixed time periods called epochs, where a one-time bootstrapping protocol is executed to agree on a committee of nodes. Each epoch ends with the generation of fresh randomness, which is used for committee selection, node identity generation, and reconfiguration. The protocol ensures robustness through a Cuckoo rule-based reconfiguration mechanism and an intra-committee consensus protocol that tolerates up to 1/2 Byzantine faults. RapidChain's performance and security are evaluated through a prototype implementation, demonstrating superior throughput and latency compared to state-of-the-art sharding-based protocols. The protocol also addresses challenges such as Sybil attacks, low fault resiliency, and high failure probability, making it a more decentralized and efficient solution for large-scale blockchain applications.RapidChain is a sharding-based public blockchain protocol designed to overcome the performance and scalability limitations of current blockchain protocols. It achieves this by splitting the processing of transactions among multiple smaller groups of nodes, known as committees, which work in parallel to maximize performance while reducing communication, computation, and storage per node. Unlike existing sharding-based protocols that require a linear amount of communication per transaction, RapidChain introduces an optimal intra-committee consensus algorithm, a novel gossiping protocol for large blocks, and a provably secure reconfiguration mechanism. These innovations enable RapidChain to process over 7,300 transactions per second with an expected confirmation latency of about 8.7 seconds in a network of 4,000 nodes, achieving a time-to-failure of more than 4,500 years. RapidChain's key contributions include: - **Sublinear Communication**: It is the first sharding-based blockchain protocol that requires only a sublinear number of bits exchanged in the network per transaction. - **Byzantine Fault Tolerance**: It is resilient to Byzantine faults from up to a 1/3 fraction of its participants. - **Complete Sharding**: It achieves complete sharding of communication, computation, and storage overhead without assuming any trusted setup. The protocol operates in fixed time periods called epochs, where a one-time bootstrapping protocol is executed to agree on a committee of nodes. Each epoch ends with the generation of fresh randomness, which is used for committee selection, node identity generation, and reconfiguration. The protocol ensures robustness through a Cuckoo rule-based reconfiguration mechanism and an intra-committee consensus protocol that tolerates up to 1/2 Byzantine faults. RapidChain's performance and security are evaluated through a prototype implementation, demonstrating superior throughput and latency compared to state-of-the-art sharding-based protocols. The protocol also addresses challenges such as Sybil attacks, low fault resiliency, and high failure probability, making it a more decentralized and efficient solution for large-scale blockchain applications.