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Hydra: A Multiple Blockchain Protocol for Improving Transaction Throughput
Improving transaction throughput is one of the main challenges in decent...
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XOX Fabric: A hybrid approach to transaction execution
Performance and scalability are a major concern for blockchain systems t...
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Attacking the DeFi Ecosystem with Flash Loans for Fun and Profit
Credit allows a lender to loan out surplus capital to a borrower. In the...
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Tree-Chain: A Fast Lightweight Consensus Algorithm for IoT Applications
Blockchain has received tremendous attention in non-monetary application...
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Metamorphic IOTA
IOTA opened recently a new line of research in distributed ledgers area ...
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On the Just-In-Time Discovery of Profit-Generating Transactions in DeFi Protocols
In this paper, we investigate two methods that allow us to automatically...
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Transaction Pricing for Maximizing Throughput in a Sharded Blockchain Ledger
In this paper, we present a pricing mechanism that aligns incentives of ...
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Denial-of-Service Vulnerability of Hash-based Transaction Sharding: Attacks and Countermeasures
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.
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