A Survey on Consensus Algorithms in Blockchain Based on Post Quantum Cryptosystems

Blockchain is a distributed, decentralized ledger mechanism with a various features. It is used in diverse applications nowadays, from financial sector to password management. It does not have any central tool to validate and verify the transactions, yet every transaction in the Blockchain is secured and verified. This is achieved because of a consensus algorithm in the network. Latest study reports show that emergence of quantum computing will impact the overall safety of Blockchain and its internal working. Attacks using Grover's and Shor's algorithm can threaten the hashing and public key schemes in cryptography. It will force a complete redesign of the Blockchain systems to withstand quantum attacks. So there is a need to develop quantum-safe Blockchain systems. Consensus mechanisms like Proof of Work (PoW) and Signing algorithms like Elliptic Curve Cryptography used in Blockchain can be modified to overcome quantum attacks. Here a comparative study and analysis of different consensus algorithms developed using post-quantum cryptosystems are done, which can be implemented in Blockchain systems to make them quantum safe.