Blockchain Security: Strategies Against Sybil Attacks

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Securing the foundation of decentralized financial systems has been a focal point of my research for quite some time. Inside blockchains, a vulnerability arises in the form of fake nodes, known as the Sybil attack. In this scenario, malicious nodes seize control of 51% of the nodes on the blockchain, gaining control. This threat extends beyond decentralized banking systems; it's also used differently on social media platforms.

Individuals create numerous accounts to engage in trolling behaviour or boost engagement metrics, such as likes. Some users even purchase bots to inflate their follower counts, reaching the million-follower milestone.

This issue is becoming deeply intertwined with everyday life. In the physical world, you wouldn't allow a stranger to enter your home or follow your family. So, why would you accept such intrusion online? Most people share a wealth of personal information online.

There are different styles of Sybil attacks. A direct Sybil attack involves malicious nodes interacting with honest nodes so they can manipulate them. An indirect Sybil Attack occurs when hackers use proxy nodes to hide behind, making them look legitimate.

An eclipse attack involves a malicious actor isolating a specific user or node within a decentralized network. In executing this attack, the hacker redirects the target's incoming and outgoing connections away from legitimate neighbouring nodes to nodes under the hacker's control. This node could then carry out whatever the hacker instructs.

How would this work?

Start with a Sybil Attack to introduce multiple fake identities or nodes into the network. By doing so, the attacker increases their influence over the network, reaching a point where they can control a significant portion of the chain.

Once the Sybil nodes are established, the attacker can then execute an Eclipse Attack on a specific target within the network. By isolating this target, the attacker can control its communications and interactions. The combination of these attacks allows the malicious actor not only to manipulate the overall network but also to target and compromise individual nodes or users.

When it's easy to make nodes, it's easy for the Sybil attack to set up nodes. An attacker can deploy a bot to make the nodes. Attackers can also manipulate validation systems. Blockchain revenues attract hackers. Ethereum understands this all too well. The idea is to make it much harder for nodes to be established.

A Markov Chain is a mathematical concept used to model a sequence of events where the outcome at any given step depends only on the preceding step. It's a type of stochastic process, meaning that it involves a degree of randomness. Google uses this to predict your next word. A Markov Chain is very powerfully used with AI as well.

Markov Chains are used in real-world situations, like predicting stock prices, analyzing user behaviour online, or understanding how diseases spread. It's a handy tool for understanding and predicting events based on what's happening now.

Markov Chains can be applied in Modeling user behaviour, analyzing traffic, and developing Intrusion Detection Systems (IDS) to model normal system behaviour. Sudden changes from the expected sequence of events can then trigger alerts for potential security breaches of all kinds.

Decentralized Identifiers (DIDs) are like your online alter ego, offering you absolute control. You decide what information to share, just as you would in real life. DIDs provide you with a unique code or "identifier," much like your name or ID number. You can enhance this by incorporating your fingerprint, facial scan, or your DNA for added security. This not only safeguards users within a blockchain but it also eliminates the need for a central authority. DIDs seamlessly integrating with Smart contracts of your choosing, can link you to a plethora of services from your social media accounts to your bank and even your passport.

A hierarchical system can be employed to enhance protection against Sybil attacks by organizing participants in a structured manner. Users at higher levels can have more privileges and responsibilities. This structure can make it more challenging for attackers to compromise the entire network. Incorporating a form of Social trust graphs (SybilRank, for example) will enhance security.

Building your own personal defence system is recommended. We can use the example of how I2p works, a system that allows millions of computers to self-organize into a decentralized network. This will prevent the need for a central registry and minimize the risk of a single point of failure. Enabling communication and resource sharing among computers in the network, and routing around unavailable nodes makes it challenging for attackers to disrupt the network. Leveraging the use of long-lived nodes and making those more trusted. XOR metric checks if pairs of numbers are the same (0) or different (1). For example, in codes 1010 and 1001: 1 and 1 (0), 0 and 0 (0), 1 and 0 (1), 0 and 1 (1). The answer would be 0011. This helps ensure real identities on a blockchain.

We can also add; Making participation in the network resource-heavy. In PoW, this means requiring significant computational power, and in PoS, it involves taking a considerable amount of cryptocurrency. This will raise the cost for attackers to create and maintain multiple identities. Using randomized selection mechanisms in PoS to choose validators will make it harder for attackers to predict the next node. Adding a reputation system that rewards long-term participation. This will discourage attackers, making the need to build and maintain a positive reputation over time, making quick Sybil attacks less effective. As a network grows, increasing the token or resource requirements for participation makes scaling a Sybil attack more difficult and expensive. Automated periodic revalidation of participants will ensure they continue to meet the requirements. This will add an ongoing cost for attackers to maintain their fake identities.

Let the Community governance decisions; like a direct democracy.

Letting participants collectively decide on rules and mechanics, ensures that any changes to the system are agreed upon by a majority, making it harder for a single entity to manipulate the network. Create incentives for participants to report suspicious activity adding an extra layer of security as the community actively polices the network.

Zero Trust principles added to blockchain systems add an extra layer of security by assuming that no entity, internal or external, should be automatically trusted. This approach enhances the resilience of blockchain networks against evolving cyber threats and vulnerabilities.

Ensuring the safety and trustworthiness of the blockchain involves careful consideration. I addressed Sybil attacks. My aim is to make the blockchain's security of a higher level and make manipulation more challenging. By implementing strategies like DIDs, Markov Chain, PoW/PoS, hierarchical structures, social trust graphs, and embracing Zero Trust principles we can secure our world or even write better ideas. Of course there is a lot more to securing but this is a challenge easily over come.

A motto to live by is "Never trust, always verify".