Sybil Attack

Sybil Attack is a type of breach seen in peer-to-peer systems in which a node in the grid operates multiple identities vigorously at the same time and weakens the authority in reputation systems. The focal purpose of this attack is to gain the middle-of-the-road influence in the network to carry out illicit this is with respect to guidelines and regulations set with in the network actions in the system. A single entity- a computer system has the ability to produce and activate multiple identities. To outside viewers, these numerous fake identities seem to be real inimitable identities.

This attack receives its name form a case study about a woman named Sybil Dorsett, who was treated for Dissociative Identity Disorder. If you are interested in understanding more about this particular case, we suggest that you watch the movie based on the same- “Sybil” (2007). A paper called The Sybil Attack was written by John R. Douceur at the Microsoft Research.

How the Bitcoin network prevents sybil attack?

Bitcoin grid uses the Proof of Work (PoW) consensus algorithm to prove the legitimacy of any block that is added to the blockchain. A substantial amount of computing power is essential to do the work which delivers imbursement motivation to the miners to do authentic work which means a bitcoin reward of 12.5 bitcoins for every block mined is given to the miners and no incentive for the defective work. The dealings are authenticated by every node and vetoed as inacceptable if defective transactions are included in the block. A type of sybil attack, called the 51% attack is also virtually impossible in the bitcoin system because of so many miners, it is very tough for a single group to control 51% of the miners.

Ways to prevent sybil attack

Giving different power to different members – This is on the basis of repute systems. Members with dissimilar power levels are given diverse reputation levels.

Cost to create an identity – To avert multiple false identities in the network, we can put a cost for every identity that aims to join the network. A point to note is that it makes more sense to make it infeasible to operate multiple fake identities at the same time rather than creating new identities. Multiple identities can enforce security, anonymity, censorship prevention.

Validation of identities before joining the network –

Direct validation: An already recognized member authenticates the new joiner of the network.

Indirect validation: An established member authenticates some other members who can, in turn, verify other new network joiners. As the members authenticating the new joiners are verified and validated by an established entity, the new joiners are trusted to be honest.