Sybil Resistance

A consensus mechanism that requires participants (miners) to expend significant computational energy to solve cryptographic puzzles, thereby validating transactions and creating new blocks. The high, real-world cost of electricity and hardware acts as a sybil-resistant barrier, making it economically irrational for an attacker to amass enough computational power (a 51% attack) to control the network. Example: Bitcoin.

A consensus mechanism where validators are chosen to create new blocks based on the amount of cryptocurrency they have staked (locked) as collateral. Sybil resistance is enforced through economic slashing, where malicious validators can have a portion of their stake destroyed. Acquiring enough stake to attack the network becomes prohibitively expensive and self-destructive. Example: Ethereum, Cardano.

A mechanism that aims to cryptographically verify that each participant is a unique human, not a bot or duplicate identity. This directly targets the Sybil problem by linking network rights to biometric or government-verified credentials. Techniques include biometric verification (e.g., iris scanning) and social graph analysis. Example: Worldcoin's World ID, BrightID.

A decentralized curation system where listing or voting rights are gated by the deposit of a native token. To submit a malicious entry or vote, an attacker would need to acquire a large portion of the token supply, raising its market price and making the attack costly. This creates cryptoeconomic sybil resistance for applications like reputation systems and curated lists.

A governance and funding mechanism where the cost of casting additional votes scales quadratically. For example, 1 vote costs 1 credit, but 10 votes cost 100 credits. This design severely limits the influence a sybil attacker can gain by creating many identities, as the cost to sway an outcome becomes astronomically high compared to a system of one-person-one-vote. Example: Gitcoin Grants.

A decentralized identity model where trust and uniqueness are established through a network of attestations from known entities. A new participant proves they are not a Sybil by obtaining verifications from existing, trusted members of the graph. This method underpins decentralized identity systems and is used in protocols like Proof of Humanity, where participants vouch for each other's uniqueness.

A foundational sybil resistance mechanism where participants must expend significant computational power to create new blocks. The high cost of electricity and hardware makes creating a large number of fake identities (Sybils) economically prohibitive. This secures networks like Bitcoin by ensuring that influence over consensus is tied to real-world resource expenditure.

• Key Feature: One-CPU-one-vote model.
• Example: Bitcoin mining requires specialized ASIC hardware.

A sybil resistance mechanism where validators must lock (stake) the network's native cryptocurrency as collateral. The probability of being chosen to propose or validate a block is proportional to the size of the stake. Attempting a Sybil attack requires acquiring and staking a prohibitively large amount of capital, which can be slashed (destroyed) for malicious behavior.

• Key Feature: One-coin-one-vote model.
• Example: Ethereum validators must stake 32 ETH.

A mechanism designed to verify that each participant is a unique human, directly countering Sybil attacks. This is often achieved through biometric verification, government ID checks, or decentralized solutions like social graph analysis or video attestation. It's crucial for applications requiring fair distribution, like universal basic income (UBI) pilots or quadratic voting.

• Key Feature: One-person-one-vote.
• Example: Worldcoin uses iris biometrics for unique human verification.

Sybil resistance is a primary challenge in fair token distribution events. Projects use on-chain analysis to filter out Sybil clusters before an airdrop. Common techniques include analyzing transaction history, gas spent, and network interaction depth to distinguish real users from farmers who control multiple wallets.

• Key Technique: Graph analysis to identify wallet clusters controlled by a single entity.
• Consequence: Sybil attacks can drain value meant for genuine users, harming project sustainability.

In DAOs, Sybil resistance ensures voting power isn't gamed by creating multiple identities. Mechanisms include:

• Token-weighted voting: Power is tied to staked tokens (susceptible to wealth concentration).
• Proof-of-Personhood: Grants one vote per verified human.
• Conviction Voting: Voting power increases the longer tokens are committed to a proposal, raising the cost of attack. Without sybil resistance, governance can be easily captured.

Sybil resistance is often delegated to the underlying Layer 1 (e.g., Ethereum). Rollups (Optimistic, ZK-Rollups) inherit security from the L1's consensus mechanism. However, sequencing and proving within the L2 may introduce new attack vectors where a Sybil attacker could censor transactions if they control the sequencer role, highlighting the need for decentralized sequencer sets.

A direct, non-cryptoeconomic method of sybil resistance that relies on verifying a user's unique, real-world identity. This is common in decentralized identity (DID) systems and some governance models.

• Methods: Government-issued ID verification, biometrics, or trusted third-party attestations.
• Use Case: Projects like Proof of Humanity and BrightID create sybil-resistant social graphs for fair airdrops and governance, ensuring one-person-one-vote.

A technique for detecting sybil attacks by analyzing the relationships and interaction patterns between accounts. Sybil accounts often exhibit abnormal connectivity, such as forming dense clusters with few links to legitimate users.

• How it works: Algorithms assess trust and reputation based on network topology, identifying fake accounts that lack organic social connections.
• Application: Used by platforms like Gitcoin Grants during their Quadratic Funding rounds to downweight donations from suspected sybil clusters.

The core economic principle behind sybil resistance: creating a new identity must have a non-trivial, unavoidable cost that outweighs the potential benefit of an attack. The system's security relies on making sybil attacks financially irrational.

• PoW Cost: Electricity and hardware depreciation.
• PoS Cost: Opportunity cost of locked capital and slashing risk.
• Analysis: A robust system designs its cost function so that the attack cost is orders of magnitude higher than the possible reward.

The primary threat that sybil resistance mechanisms are designed to prevent. It occurs when a single entity gains control of the majority of a network's consensus resources (hash rate in PoW, staked value in PoS), allowing them to censor transactions or double-spend.

• Sybil Connection: An attacker could, in theory, create a sybil army of nodes, but the cost function (PoW/PoS) makes acquiring a majority prohibitively expensive.
• Real-World Example: Smaller PoW blockchains like Ethereum Classic have suffered 51% attacks, demonstrating the consequence of insufficient sybil resistance due to low total hash power.