Sybil Attack is a sort of assault found in distributed systems wherein a hub in the system works various characters effectively in the meantime and undermines the specialist/control in the frameworks. The primary point of this assault is to pick up most of impact in the system to do illegal(with regard to principles and laws set in the system) activities in the framework. A solitary entity(a PC) has the capacity to make and work numerous identities. To outside eyewitnesses, these different phony characters have all the earmarks of being genuine one of a kind identity. A common instance is the fifty-one percent attack on blockchains.