Block Chain technologies is quite under discussion in the biometric era of this decade, since many cryptocurrency has adopted this technology in their transactions, applied in 2009 by Bitcoin, with unique P2P communication method, it has become the supreme secure method in any biometric or crypto transactions. In Block chain, the information format of blocks was standardized, no extra information was allowed to be added in the block, which limits the interaction between biometrics and Blockchain.
Block chain is a distributed ledger that is completely open to anyone in the chain. Once data is recorded in a block, it becomes very hard to change. each block contains DATA, HASH and the “HASH of the previous block” the data stored inside the block is subject to the Block Chain.