# A Survey on Consensus Protocols and Attacks on Blockchain Technology
## 7 Other Important Attacks  
In [87], [PERSON] et al. divided sharding blockchains into a number of components, each of which is examined for its underlying concepts, existing techniques, and potential issues. Designing a new sharding blockchain system might be reduced to putting together a number of distinct components on this basis. As a result, each component could be improved independently based on the most recent research, and the improved component could be integrated into a whole sharding blockchain system without compromising the security of other parts or the entire system. The potential problems and future research directions proposed in this paper are worthy of consideration for each component.  
In [88], the authors present a knowledge systematization for blockchain sharding. They identified key components and difficulties in sharding. The ability to place participating nodes uniformly into shards is dependent on publicly verifiable randomness. A consensus protocol is required within each shard to reach an agreement on the blocks. Existing solutions are dominated by BFT-based protocols. The protocol must ensure atomic properties for cross-shard transactions. Finally, at the end of an epoch, a reconfiguration process is required. They examined several well-known blockchain sharding protocols before debating potential research directions.  
In [89], [PERSON] et al. outlined sharding knowledge, and emphasized the need for sharding in systematized and scalable blockchain design, which includes cross-shard transaction atomicity, intra-shard consensus protocol, and general enhancements. They also presented precise computations and unique insights based on multidimensional analysis of the features and constraints of the investigated sharding processes, as well as a comprehensive comparison and evaluation.  
In [90], the authors present several consensus protocols for comparing the qualities of blockchain technology in terms of computation, vulnerabilities, and other factors. They provide a complete view of public and private blockchains and also present a taxonomy of all consensus protocols. Finally, the analysis of those protocols yields a comparison table.  
In [91], [PERSON] et al. conducted intensive reviews on the latest and future contests in blockchain and have reviewed five major attacks, demonstrating that current protection techniques are insufficient, leaving this technology vulnerable to attackers. One of the innovative consensus methods is proof of adjourn (PoAj), which can overcome attacks such as one endorsement attacks, 51 percent occurrence, transaction confirmation latency, zero confirmation assaults, and miner bribery.  
In [92], the authors investigate the blockchain's attack surface and assign attacks to the blockchain's cryptographic constructions, the causal communication construction, and the environment in which they are utilized. They draw attention to important dangers and ongoing defense research. They believe that, despite current and established defenses, numerous attacks on blockchains can still be launched, with some of those assaults being exploited to aid the launch of others. They suggest new research avenues that must be followed in order to make blockchains more secure and effective by defining these assaults and reviewing their responses.  
In [65], [PERSON] et al. highlighted a study on blockchain and blockchain attacks and their solutions, as previously described. They investigated the affected and conducted areas, as well as the double-spending attack. They provided a solution after demonstrating the limitations of the double-spending attack. They create a pattern of real-world blockchain attacks which will be beneficial to new researchers in this field. On the other hand, if we can raise funds and implement a proposed model in the real world, we may be able to protect our bitcoins from a double-spending attack.