Immutability Measure for Different Blockchain Structures

Abstract

The main advantage of Blockchain technology is the immutability of data maintained by decentralized systems. Earlier studies introduce the probability of attackers succeeding in modifying legitimate data in the blocks. We propose “immutability measure”, a metric that indicates the degree of difficulty in modifying existing data in Blockchain. We propose different blockchain structures that can be more appropriate for different applications. There are several parameters that determine the difficulty of modifying data in Blockchain. We analyze the impact of each of these parameters on the immutability measure of various blockchain structures. We also study the required computational and electrical power as well as the time for a successful attack in various blockchain structures. We demonstrate that our proposed blockchain structures can exponentially improve the immutability measure with a nominal increase in computing resources.