## Introduction
Selfish mining, also known as block holding, is a type of attack on blockchain systems in which an attacker mines blocks on their own fork of the blockchain without publishing them to the network. This strategy allows an attacker to gain an advantage over honest nodes, which can lead to disruption of the network and increased rewards for dishonest participants. This article discusses the mechanisms of selfish mining, its impact on blockchain systems, and possible measures to mitigate the consequences of such attacks.
## Selfish mining mechanism
In selfish mining, an attacker creates his own fork of the blockchain and mines blocks without publishing them to the network. Once the attacker calculates the desired number of blocks, he transmits them to the network, seeking to return the main block chain to his control. The purpose of this attack can be twofold:
1. Network disruption: An attacker can waste the resources of honest nodes by forcing them to work on outdated blocks.
2. Increased rewards: Dishonest nodes can receive more rewards for mined blocks since they control a larger part of the chain.
## Impact on blockchain systems
### Proof of Work (PoW)
Selfish mining is especially dangerous for blockchains that use the Proof of Work (PoW) protocol. In such systems, an attacker can significantly increase his chances of receiving rewards by controlling most of the computing power. This leads to uneven distribution of rewards and decreased trust in the network.
### Proof of Stake (PoS)
Blockchains that use the Proof of Stake (PoS) protocol are less susceptible to selfish mining. In PoS systems, validators are selected based on their share of the network rather than their computing power. This makes block holding attacks less effective because the block validation process cannot be easily controlled by an attacker.
## Measures to mitigate the consequences of attacks
To protect blockchain systems from selfish mining, the following measures can be applied:
1. Reducing Conditions: Introducing conditions that reduce rewards for nodes participating in attacks can reduce incentives for selfish mining.
2. Removing Offenders: Removing nodes found to be engaging in dishonest activity from their positions of power will deprive them of future rewards and reduce the likelihood of repeat attacks.
## Conclusion
Selfish mining poses a serious threat to blockchain systems, especially those using the Proof of Work protocol. However, with the use of appropriate mitigation measures, such as curtailment terms and suspension of offenders, the risks associated with such attacks can be significantly reduced. It is important to continue researching and developing new security methods to ensure the security and resilience of blockchain networks.
## Links
– Study of long-range attacks on Proof of Stake protocols: IEEE Xplore
