Research On Key Technologies Of Block Withholding Attack In Blockchain

The Bitcoin system is based on the Proof-of-Work(Po W).Currently,several attack methods against Po W(such as Selfish Mining,Block Withholding and Fork After Withholding)may cause serious damage to the Bitcoin system.Based on the Block Withholding(BWH)attack and the Fork After Withholding(FAW)attack,a greedy BWH attack method and a cooperation-based FAW attack method are proposed in this dissertation.The research content is shown as follows:(1)In this dissertation,a greedy BWH attack method is proposed.Firstly,a strategy based on BWH is presented for generating Denial-of-Service attacks.The mining power loss factor is used to represent the mining cost of miners,and it is proved that when the mining power loss factor reaches 75%,the attacker can make the honest miner to deny service with about 28% of the honest miner’s mining power.However,the pure Denial-of-Service attack based on BWH does not significantly increase the revenue of the attacker.Based on this strategy,the concept of “sponsoring mining pool”is introduced,where sponsoring mining pools hire attackers to target honest mining pools and induce them to deny service.This approach enhances the gains of both the attacker and the sponsoring mining pool.The study investigates the attacker’s revenue using this method in the conditions of single mining pool,multiple mining pool and double mining pool game.It is proved that in the single mining pool attack,the revenue of greedy BWH attacker can increase by up to 160% compared with honest mining,and the BWH attack is 14% under the same condition.In the multi-pool attack,the revenue of the greedy BWH attacker can be increased by up to 153% compared with the honest mining.In the double mining pool game,the greedy BWH attacker is easy to fall into the “Miner’s Dilemma”,and the attackers are less willing to launch an attack.It is proved that the greedy BWH attack is more threatening than BWH attack.(2)In order to break the “Miner’s Dilemma” and improve the attacker’s revenue,a cooperation-based variation of FAW attack is proposed in this dissertation.Firstly,the concept of “cooperative mining pool” is introduced,where the attacker can collaborate with a mining pool to shield it from FAW attacks.In return,the attacker charges a collaboration fee to increase their own revenue.In addition,the attacker can adjust the proportion of infiltration mining in the mining round to achieve better mining revenue.Experiments show that in the single mining pool attack,the revenue increase rate of the cooperation-based FAW attacker is 6.83% higher than FAW,and the revenue increase rate of the cooperative mining pool is 4% higher than FAW.In the multi-mining pool attack,the revenue increase rate of the cooperation-based FAW attacker is 5% higher than FAW.It is proved that the revenue of cooperation-based FAW attacker and cooperative miner is higher than FAW,and cooperation-based FAW attack is more threatening than FAW.