OptChain: Achieving Optimal Throughput of Permissionless Blockchains

• URL: http://arxiv.org/abs/2606.23405v1
• Date: Mon, 22 Jun 2026 14:30:10 GMT
• Title: OptChain: Achieving Optimal Throughput of Permissionless Blockchains
• Abstract summary: We introduce OptChain, a permissionless blockchain state machine replication (SMR) protocol that achieves optimal throughput.<n>We first establish a theoretical upper bound on the throughput of any SMR protocol under a fixed error probability, and OptChain is the first protocol to approach this limit.<n>We implement a full prototype of OptChain and deploy it on AWS EC2 nodes across various regions.
• Score: 22.07619176972099
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We introduce \textit{OptChain}, a permissionless blockchain state machine replication (SMR) protocol that achieves optimal throughput. We first establish a theoretical upper bound on the throughput of any SMR protocol under a fixed error probability, and OptChain is the first protocol to approach this limit. Conceptually, OptChain is a sharding protocol that optimizes both vertical and horizontal scalability. Vertically, we introduce \textit{Shardis}, a novel permissionless verifiable information dispersal mechanism that maximizes intra-shard throughput to its physical limit, determined by the fastest node's bandwidth within each shard. Horizontally, we propose \textit{diffusion mining}, which ensures security as long as each shard includes at least one honest node, thereby allowing for the maximum number of shards. We provide a formal security and efficiency analysis, demonstrating that OptChain approaches the established upper bound while maintaining robust security. Finally, we implement a full prototype of OptChain and deploy it on AWS EC2 nodes across various regions. Experimental results indicate that OptChain outperforms state-of-the-art permissionless protocols and closely approaches the theoretical optimal throughput.

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