Timed data delivery is a critical service for time-sensitive applications that allows a sender to deliver data to a recipient, but only be accessible at a specific future time. This service is typically accomplished by employing a set of mailmen to complete the delivery mission. While this approach is commonly used, it is vulnerable to attacks from realistic adversaries, such as a greedy sender (who accesses the delivery service without paying the service charge) and malicious mailmen (who release the data prematurely without being detected). Although some research works have been done to address these adversaries, most of them fail to achieve fairness. In this paper, we formally define the fairness requirement for mailmen-assisted timed data delivery and propose a practical scheme, dubbed DataUber, to achieve fairness. DataUber ensures that honest mailmen receive the service charge, lazy mailmen do not receive the service charge, and malicious mailmen are punished. Specifically, DataUber consists of two key techniques: 1) a new cryptographic primitive, i.e., Oblivious and Verifiable Threshold Secret Sharing (OVTSS), enabling a dealer to distribute a secret among multiple participants in a threshold and verifiable way without knowing any one of the shares; and 2) a smart-contract-based complaint mechanism, allowing anyone to become a reporter to complain about a mailman’s misbehavior to a smart contract and receive a reward. Furthermore, we formally prove the security of DataUber and demonstrate its practicality through a prototype implementation.

中文翻译：

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超越安全性：在邮递员辅助的定时数据传输中实现公平


定时数据传送对于时间敏感的应用程序来说是一项关键服务，它允许发送者将数据传送给接收者，但只能在未来的特定时间访问。这项服务通常是通过雇用一组邮递员来完成投递任务。虽然这种方法很常用，但它很容易受到现实对手的攻击，例如贪婪的发件人（在不支付服务费的情况下访问递送服务）和恶意邮递员（在不被发现的情况下过早释放数据）。尽管已经做了一些研究工作来解决这些对手，但大多数都未能实现公平。在本文中，我们正式定义了邮递员辅助定时数据传递的公平性要求，并提出了一种名为 DataUber 的实用方案来实现公平性。 DataUber 确保诚实的邮递员收到服务费，懒惰的邮递员不收取服务费，恶意邮递员受到惩罚。具体来说，DataUber 由两项关键技术组成：1）一种新的加密原语，即不经意且可验证的阈值秘密共享（OVTSS），使交易者能够以阈值和可验证的方式在多个参与者之间分发秘密，而无需知道其中任何一个分享; 2）基于智能合约的投诉机制，允许任何人成为记者，向智能合约投诉邮递员的不当行为并获得奖励。此外，我们正式证明了DataUber的安全性，并通过原型实现展示了其实用性。