International Journal of Network Management

Study presents a review on security threats and vulnerabilities in existing cryptocurrency systems that include the possibility of attacks with a focus on issues related to user privacy and transaction anonymity. The real attacks on blockchain systems are investigated, and current possible countermeasure methods by attack types are discussed. Furthermore, practical and academic merits to enhance the security of blockchain and limitations of state-of-the-art security solutions are summarized and discussed, and future directions in area of blockchain security are suggested.

This work shows how a permissioned blockchain framework such as Hyperledger Fabric can be re-engineered to support nearly 20 000 transactions per second, a factor of almost 7 better than the prior work. We accomplished this goal by implementing a series of independent optimizations focusing on I/O, caching, parallelism and efficient data access. We also use aggressive caching, and we leverage lightweight data structures for fast data access on the critical path.

We propose a blockchain-based solution to automate the issuance of degree certificates in the Brazilian higher education system. The goal is to tackle unmanaged risk, bureaucracy, human interference, and frauds. The solution consists of Ethereum smart contracts that allow higher education institutions to register students' academic achievements. The Brazilian Public Key Infrastructure is used to identify institutions in the blockchain. When the smart contracts identify that a student has completed a degree, they issue a degree certificate in the blockchain.

This review paper classifies the CPP, critically analyzes the existing solutions, finds limitations, and future scope existing which will help to potential researchers in this area to innovate new solutions for CPP lying on this information. Different aspects of our review are the classification of CPP based on the capacity of controllers, network traffic which may be static or dynamic traffic, fault-tolerance and network partitioning. We also present open research issues in CPP raised by researchers and industry professionals around the globe.