- A Sybil attack is a cyber threat aimed at gaining control over a significant number of nodes.
- Sybil attacks can result in blocked transactions, double spending, and the spread of misinformation.
- Gitcoin Passport developers are going the extra mile to create a unique web3 passport.
Decentralization is one of the most revolutionary ideologies that has transformed the digital world. In the past, and indeed in some places today, centralized governments have expressed totalitarian control over resources that belong to the community.
This is the same scenario in the digital world, where centralized systems hoard data that belongs to the community, and one of the ways this was able to be accomplished was through Sybil attacks.
Sybil attacks leave one individual or a group of individuals with an influential control over a decentralized system, indirectly turning it into a centralized system. For the blockchain world to survive and even thrive, it is important to understand how Sybil attacks work and how to deal with them.
Understanding Sybil Attacks: The What, The Who, and The How
A Sybil attack is a cyber threat to the security of a system by a malicious player whose intention is to gain control over a significant number of nodes.
The word ‘Sybil’ originated from the protagonist of the 1973 book Sybil. The book is a story about a young lady with Disassociative Identity Disorder. In the early 2000s, Biran Zill and John R. Douceur, researchers at Microsoft adopted the name when they defined the Sybil attack as it pertains to digital systems.
In a Sybil attack, the hacker disguises the nodes he controls as independent and separate nodes, effectively tricking the rest of the network participants into thinking the network is still safe.
This can result in a 51% attack, whose impact includes censorship of transactions on the network. In a proof of stake (PoS) blockchains like Ethereum, a Sybil attack which results in a 51% attack may lead to issues such as blocked transactions, while on proof of work (PoW) networks like Bitcoin, it can lead to double spending.
Sybil attacks are a menace to the goal of decentralization as they frustrate the equal and fair distribution of resources. In crypto airdrops, Sybil attackers often end up receiving disproportionately large amounts of tokens which they either dump on the market or use to influence DAO governance in their favor.
Theoretical Frameworks for Sybil Attack Mitigation
There are two primary types of Sybil attacks: direct and indirect Sybil attacks. In the former, malicious nodes influence the network by directly communicating with honest nodes, while in the latter, malicious nodes aim to artificially increase the reputation of particular (affected) nodes, altering network topology.
There are several known approaches to prevent and control Sybil attacks. Here are some of them:
1. Identity Validation
To overcome the problems of Sybil attacks, identity validation is important as it will help in unveiling the masquerading malicious players. Identity validation works by establishing a direct connection between an identity(user) and an entity(wallet address). This is the famous process of KYC that is now rampant in cryptocurrency airdrop projects.
Projects like Gitcoin Passport are going the extra mile to create a unique web3 passport that ensures one identity for one entity.
2. Deploying Social Trust Graphs
A social graph is a technique that involves the mapping of social relations between entities. It represents a social network created using the graph theory. Using this feature, Sybil prevention tools like SybilGuard, SybilLimit, Advogato Trust Metric, and SybilRank, among others, have been developed. All of them work differently to identify Sybil attackers and block their attempts to control distributed P2P networks.
3. Raising the Cost of Attack
Imposing economic costs as a barrier for Sybil attackers has proven to be quite resourceful. This mode of prevention makes Sybil attacks more expensive, discouraging the malicious player from continuing with the assault.
A good example of using economic costs to tackle Sybil attacks is Bitcoin’s Proof of Work (PoW) network. Bitcoin requires a certain proof that an entity has used a certain amount of computational power to solve the block encryption (AKA mining).
The miners are rewarded proportionally to their contributed hashrate, hence preventing any single player from amassing too much hashrate.
4. Employing Personhood Validation Techniques
In the age of airdrops, personhood validation techniques have become the order of the day. This is a method of dealing with Sybil attacks that make use of multiple fake identities. The current Tap-to-Earn airdrops have witnessed the rise of this type of Sybil attack, as airdrop farmers rush to accumulate more points.
In the past airdrops like Stark saw disproportionate tokens allocated to a few individuals due to such attacks.
Personhood validation led to the creation of Proof of Personhood and Proof of Humanity techniques, in which each human participant (identity) would be allocated exactly one vote. Gitcoin Passport is one the leading protocols to implement proof of personhood.
Conclusion
As the crypto world continues to onboard more users and the resources become more limited, Sybil attacks will increase both in intensity and frequency. While the above methods are working currently, in the future they may become obsolete with the advancement of technology. It is of utmost importance for decentralized protocols to stay vigilant and continue innovating Sybil detection and elimination tools in order to uphold decentralization.
