标题： 探索Nostr生态系统：去中心化与弹性的研究 显示英文标题

标题： Exploring the Nostr Ecosystem: A Study of Decentralization and Resilience

摘要： Nostr是一个于2022年推出的开放去中心化社交网络。 从用户的角度来看，它类似于像Twitter这样的微型博客服务。 然而，底层基础设施非常不同，Nostr具有一系列独特的功能，使其与众不同。 Nostr引入了中继的概念，这些中继作为开放存储服务器，接收、存储和分发用户帖子。 每个用户由公钥唯一标识，通过数字签名确保帖子的真实性。 因此，用户能够通过各种中继安全地发送和接收帖子，这使他们摆脱了对单一服务器的依赖，并提高了帖子的可用性（例如，使其更具抗审查性）。 Nostr生态系统已经引起了广泛关注，在短短两年内拥有400万用户和6000万条帖子。 为了了解其特性和挑战，我们进行了首次大规模的Nostr生态系统测量，时间跨度从2023年7月1日到2023年12月31日。 我们的研究重点关注两个关键方面：Nostr中继和帖子复制策略。 我们发现，与传统的Fediverse应用程序相比，Nostr实现了更优越的去中心化。 然而，中继的可用性仍然是一个挑战，其中财务可持续性（尤其是对于免费使用的中继）成为一个促成因素。 我们还发现，帖子在中继之间的复制提高了帖子的可用性，但带来了显著的开销。 为了解决这个问题，我们提出了两种设计创新。 一种是控制帖子复制的数量，另一种是在帖子检索期间减少开销。 通过数据驱动的评估，我们证明了它们的有效性，而不会对系统产生负面影响。 显示英文摘要

摘要： Nostr is an open decentralized social network launched in 2022. From a user's perspective, it is similar to a micro-blogging service like Twitter. However, the underlying infrastructure is very different, and Nostr boasts a range of unique features that set it apart. Nostr introduces the concept of relays, which act as open storage servers that receive, store, and distribute user posts. Each user is uniquely identified by a public key, ensuring authenticity of posts through digital signatures. Consequently, users are able to securely send and receive posts through various relays, which frees them from single-server reliance and enhances post availability (e.g., making it more censorship resistant). The Nostr ecosystem has garnered significant attention, boasting 4 million users and 60 million posts in just 2 years. To understand its characteristics and challenges, we conduct the first large-scale measurement of the Nostr ecosystem, spanning from July 1, 2023, to December 31, 2023. Our study focuses on two key aspects: Nostr relays and post replication strategies. We find that Nostr achieves superior decentralization compared to traditional Fediverse applications. However, relay availability remains a challenge, where financial sustainability (particularly for free-to-use relays) emerges as a contributing factor. We also find that the replication of posts across relays enhances post availability but introduces significant overhead. To address this, we propose two design innovations. One to control the number of post replications, and another to reduce the overhead during post retrieval. Via data-driven evaluations, we demonstrate their effectiveness without negatively impacting the system.