Polar Coded Merkle Tree: Improved Detection of Data Availability Attacks in Blockchain Systems

TL;DR

This paper introduces the Polar Coded Merkle Tree (PCMT), a novel structure combining polar codes and Merkle Trees to enhance detection of data availability attacks in blockchain systems, especially for large blocks.

Contribution

The paper proposes the PCMT, integrating polar codes with Merkle Trees and a new SEF polar code construction to improve DA attack detection in large blockchain blocks.

Findings

PCMT effectively detects DA attacks in large blocks.

SEF polar codes improve scalability and performance.

PCMT outperforms previous LDPC and 2D-RS code methods.

Abstract

Light nodes in blockchain systems are known to be vulnerable to data availability (DA) attacks where they accept an invalid block with unavailable portions. Previous works have used LDPC and 2-D Reed Solomon (2D-RS) codes with Merkle Trees to mitigate DA attacks. While these codes have demonstrated improved performance across a variety of metrics such as DA detection probability, they are difficult to apply to blockchains with large blocks due to generally intractable code guarantees for large codelengths (LDPC), large decoding complexity (2D-RS), or large coding fraud proof sizes (2D-RS). We address these issues by proposing the novel Polar Coded Merkle Tree (PCMT) which is a Merkle Tree built from the encoding graphs of polar codes and a specialized polar code construction called Sampling-Efficient Freezing (SEF). We demonstrate that the PCMT with SEF polar codes performs well in detecting DA attacks for large block sizes.