Distributed ledger systems (i.e., blockchains) have received a lot of attention. They promise to enable mutually untrusted participants to execute transactions while providing the immutability of the data and censorship resistance. Although decentralized ledgers are a disruptive innovation, as of today, they suffer from scalability, privacy, or governance issues. Therefore, they are inapplicable for many important use cases, where interestingly, centralized ledger systems might gain adoption. Unfortunately, centralized ledgers have also drawbacks, e.g., a lack of efficient verifiability or a higher risk of censorship and equivocation. In this paper, we present AQUAREUM, a novel framework for centralized ledgers removing their main limitations. By a unique combination of a trusted execution environment (TEE) with a public blockchain, AQUAREUM provides publicly verifiable non-equivocating censorship-evident private and high-performance ledgers. AQUAREUM is integrated with a Turing-complete virtual machine (e.g., EVM), allowing arbitrary transaction processing logic, such as transfers or client-specified smart contracts. AQUAREUM is fully implemented and can process over 400 transactions per second on a commodity PC. Furthermore, we modeled AQUAREUM using the Universal Composability framework and proved its security.

翻译：分布式账本系统（即区块链）已受到广泛关注。其承诺使互不信任的参与者能够执行交易，同时保障数据不可篡改性与抗审查性。尽管去中心化账本是一项颠覆性创新，但截至目前，其仍面临可扩展性、隐私性或治理机制方面的局限。因此，在许多重要应用场景中——值得注意的是——中心化账本系统可能更具适用性。然而，中心化账本同样存在缺陷，例如缺乏高效可验证性，以及更高的审查与抵赖风险。本文提出AQUAREUM，一种消除中心化账本主要局限性的新型框架。通过将可信执行环境（TEE）与公有链独特结合，AQUAREUM能够提供公开可验证、抗抵赖、审查透明、私密且高性能的账本。该框架与图灵完备虚拟机（如EVM）集成，支持任意交易处理逻辑，包括资产转移或客户端指定的智能合约。AQUAREUM已完成完整实现，在商用PC上可实现每秒400笔以上的交易处理能力。此外，我们基于通用可组合框架对AQUAREUM进行形式化建模并证明了其安全性。