Secure Execution of Ethereum Smart Contracts over Adaptive State Sharding

This paper introduces a secure state-sharding solution for permissionless blockchains that supports both payment transactions and general Ethereum-like smart contracts. The secure partitioning of the blockchain into distinct shards continually adapts to the current transaction workload, encompassing both user and smart contract transactions. A novel two-phase commit protocol guarantees the correct execution of smart contracts distributed across different shards. Notably, this protocol offers, for the first time, support for smart contracts with nested calls across shards, without any limitation on the depth of the calling graph. An experimental study highlights the benefits of the adaptive behavior of shards during the distributed execution of such nested smart contracts.