Public key infrastructures (PKIs) provide the foundations for securing Internet communications. Currently, PKIs are operated by centralized authorities, which have been involved in numerous security incidents. Blockchain or smart contract PKIs employ their distributed, fault-tolerant log of transactions to store either all identity records, or, constant-sized data to verify identity records stored off-chain. However, as most of these systems have never been implemented, there is little information regarding their practical implications. In this article, we implement, evaluate, and provide a complete security proof for the smart contract-based PKI of (Patsonakis et al.) on Ethereum. This construction incurs constant-sized storage at the expense of computational complexity. To explore this tradeoff, we propose and implement a second construction which, eliminates the need for trusted setup, preserves its security properties and show that it is the only version with constant-sized state that can be deployed on Ethereum's live chain. We compare these constructions with the simple approach of storing all identity records on the smart contract's state, to illustrate several shortcomings of Ethereum and its cost model. We propose several modifications for fine tuning the model, which should be considered for any smart contract platform like Ethereum so that it may support arbitrary distributed applications.

中文翻译：

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实施智能合约 PKI

公钥基础设施 (PKI) 为保护 Internet 通信提供了基础。目前，PKI 由中央机构运营，这些机构已经参与了许多安全事件。区块链或智能合约 PKI 使用其分布式、容错的交易日志来存储所有身份记录，或使用恒定大小的数据来验证存储在链外的身份记录。然而，由于这些系统中的大多数从未实施过，因此关于其实际影响的信息很少。在本文中，我们为（Patsonakis 等人）在以太坊上的基于智能合约的 PKI 实施、评估并提供了完整的安全证明。这种结构以计算复杂性为代价导致了恒定大小的存储。为了探索这种权衡，我们提出并实施了第二种结构，它消除了对可信设置的需要，保留了其安全属性，并表明它是唯一可以部署在以太坊实时链上的具有恒定大小状态的版本。我们将这些结构与在智能合约状态上存储所有身份记录的简单方法进行比较，以说明以太坊及其成本模型的几个缺点。我们提出了一些对模型进行微调的修改，对于像以太坊这样的任何智能合约平台都应该考虑，以便它可以支持任意分布式应用程序。我们将这些结构与在智能合约状态上存储所有身份记录的简单方法进行比较，以说明以太坊及其成本模型的几个缺点。我们提出了一些对模型进行微调的修改，对于像以太坊这样的任何智能合约平台都应该考虑，以便它可以支持任意分布式应用程序。我们将这些结构与在智能合约状态上存储所有身份记录的简单方法进行比较，以说明以太坊及其成本模型的几个缺点。我们提出了一些对模型进行微调的修改，对于像以太坊这样的任何智能合约平台都应该考虑，以便它可以支持任意分布式应用程序。