基于哈希的交易分片的拒绝服务漏洞：攻击与对策
Denial-of-Service Vulnerability of Hash-based Transaction Sharding: Attack and Countermeasure
AI总结：
本文揭示了基于哈希的交易分片机制易受单分片泛洪拒绝服务攻击的漏洞，提出利用可信执行环境（TEE）以极低开销安全执行分片算法的对策，并在UC框架中证明了其安全性。
摘要：
自 2016 年以来，分片已成为解决传统区块链系统中可扩展性问题的极具前景的方案。尽管分片具有大幅提升区块链吞吐量的潜力，但它也带来了自身的安全问题。为了简化决定将交易放置在哪个分片的过程，现有的分片协议使用基于哈希的交易分片，其中交易的哈希值决定了其输出的分片。遗憾的是，我们表明该机制开启了一个漏洞，该漏洞可被利用来实施单分片泛洪攻击，这是一种拒绝服务攻击，旨在使单个分片过载，最终导致整个系统的性能下降。为了应对单分片泛洪攻击，我们提出了一种对策，该对策通过拒绝使用基于哈希的交易分片从根本上消除了该漏洞。该对策利用可信执行环境（Trusted Execution Environment, TEE）让区块链的验证者以可忽略的开销安全地执行交易分片算法。我们为该对策提供了正式规范，并在通用可组合性（Universal Composability, UC）框架中分析了其安全属性。最后，开发了一个概念验证来证明我们解决方案的可行性与实用性。
英文摘要：
Since 2016, sharding has become an auspicious solution to tackle the scalability issue in legacy blockchain systems. Despite its potential to strongly boost the blockchain throughput, sharding comes with its own security issues. To ease the process of deciding which shard to place transactions, existing sharding protocols use a hash-based transaction sharding in which the hash value of a transaction determines its output shard. Unfortunately, we show that this mechanism opens up a loophole that could be exploited to conduct a single-shard flooding attack, a type of Denial-of-Service (DoS) attack, to overwhelm a single shard that ends up reducing the performance of the system as a whole. To counter the single-shard flooding attack, we propose a countermeasure that essentially eliminates the loophole by rejecting the use of hash-based transaction sharding. The countermeasure leverages the Trusted Execution Environment (TEE) to let blockchain's validators securely execute a transaction sharding algorithm with a negligible overhead. We provide a formal specification for the countermeasure and analyze its security properties in the Universal Composability (UC) framework. Finally, a proof-of-concept is developed to demonstrate the feasibility and practicality of our solution.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
