Classification of double cost attack in blockchain system

Abstract

The article provides a brief overview and systematization of information on the issue of double costs in blockchain systems with probabilistic consensus methods and possible ways to solve it. The procedures using which double-cost attacks are implemented are described. The essence of the manipulations with which an attacker can try to realize double costs in decentralized payment systems is disclosed. A detailed description of the attacker's actions and ways to prevent the attack is given. The review starts with simple attacks based on creating duplicate transactions and ends with more complex attacks such as: attack-Race; Phinea attack attack; Vector76 attack; «51 %» attack.  These attacks require significant resources from the attacker and the possibility of branching the registry blockchain. The last group of attacks is analyzed in more detail with an indication of their use cases.  The most dangerous attack is highlighted. The attack «51 %»  is highlighted as the most dangerous, which, according to the authors, poses the greatest threat to the safety of blockchain systems with probabilistic consensus algorithms.