Security Implications of Blockchain Cloud with Analysis of Block Withholding Attack

TLDR

Blockchain technology offers a tamper‑proof, distributed ledger that improves performance and security in cloud computing, yet its consensus mechanism demands significant computational power, attracting greedy miners who seek to exploit the system. This paper discusses blockchain’s role in ensuring data provenance in cloud environments and identifies vulnerabilities in blockchain cloud. The authors model a block‑withholding attack in a blockchain cloud under different pool reward mechanisms. Simulations confirm that block‑withholding attacks give rogue miners ample resources to disrupt honest miners’ efforts.

Abstract

The blockchain technology has emerged as an attractive solution to address performance and security issues in distributed systems. Blockchain's public and distributed peer-to-peer ledger capability benefits cloud computing services which require functions such as, assured data provenance, auditing, management of digital assets, and distributed consensus. Blockchain's underlying consensus mechanism allows to build a tamper-proof environment, where transactions on any digital assets are verified by set of authentic participants or miners. With use of strong cryptographic methods, blocks of transactions are chained together to enable immutability on the records. However, achieving consensus demands computational power from the miners in exchange of handsome reward. Therefore, greedy miners always try to exploit the system by augmenting their mining power. In this paper, we first discuss blockchain's capability in providing assured data provenance in cloud and present vulnerabilities in blockchain cloud. We model the block withholding (BWH) attack in a blockchain cloud considering distinct pool reward mechanisms. BWH attack provides rogue miner ample resources in the blockchain cloud for disrupting honest miners' mining efforts, which was verified through simulations.