Blockchain Science Popularization: Alternative Historical Attack

Blockchain technology has become a key innovation in finance, supply chain management, and smart contracts due to its decentralized and tamper-proof nature. However, blockchain security is not foolproof, and various attack risks still exist. One such risk is the Alternative Historical Attack, also known as the Blockchain Reorganization Attack, which can undermine the validity of transactions.

What Is an Alternative Historical Attack?

An alternative historical attack occurs when an attacker manipulates the blockchain’s historical records, causing previously confirmed transactions to become invalid. Even after multiple confirmations, the attacker can replace valid transactions by creating an alternative fork of the blockchain.

Here’s how it works:

• The attacker initiates a transaction and sends funds to the recipient. The recipient sees the transaction confirmed and proceeds with delivering goods or services.
• Meanwhile, the attacker secretly mines an alternative chain containing a conflicting transaction that redirects the same funds back to themselves.
• If the attacker successfully mines a longer chain than the original one, the network recognizes this new chain as the valid one, effectively reorganizing the blockchain.
• As a result, the original transaction is reversed, and the recipient loses both the payment and the goods or services they provided.

Risks of the Attack

An alternative historical attack poses a significant risk, as recipients may suffer financial losses. Even if a transaction has received multiple confirmations, it is not always final. If an attacker successfully broadcasts a longer alternative chain, the original transaction is invalidated, leaving the recipient with nothing.

Conditions for a Successful Attack

This attack requires the attacker to have substantial computational power. If they can mine a longer chain than the existing blockchain, they can successfully reorganize the chain. Although they do not need to control the entire network, an imbalance in mining power distribution or an attacker with significant resources increases the likelihood of success.

Prevention Strategies

To mitigate the risks of an alternative historical attack, transaction recipients should implement precautionary measures:

• Increase Confirmation Requirements — Waiting for more confirmations (e.g., six confirmations) before finalizing transactions increases the computational effort required for an attack, making it less feasible.
• Monitor Network Activity — Tracking blockchain network status can help detect unusual activity and potential reorganization attempts.
• Use Additional Security Measures — High-risk transactions can be secured with multi-signature wallets, off-chain protocols, or other verification mechanisms.

Conclusion

To ensure transaction security, recipients must remain cautious and adopt protective measures. By monitoring the network and implementing enhanced security strategies, the risk of alternative historical attacks can be significantly reduced.

🦉Source: https://qitmeer.io/blogs/287