Random Mining Group Selection to Prevent 51% Attacks on Bitcoin

Bitcoin is a cryptocurrency based on blockchain technology that enables peer-to-peer transactions without a central authority. Bitcoin is known for resolving double-spending problems. When two or more miners generate a block that includes transaction information at nearly the same time, an accidental fork occurs. In this case, the longest chain of blocks is selected to avoid the double-spending problem. However, if there is an attacker node whose hash power is greater than half of the total hash power, that node can perform a double-spending attack, i.e., a 51% or majority attack. We propose a random mining group selection technique to reduce the probability of successful double-spending attacks. The analysis results demonstrate that if the number of groups is greater than or equal to two, the probability that the attacker will find the next block is less than 50%.