ELI5: 51% Attack

Advanced Definition
Last updated: Jul 28, 2023

Unraveling the 51% Attack - The Enchanted Assault on Blockchain

Greetings, young wizards and sorcerers! Today, we embark on an enchanting quest to understand the mysterious "51% Attack" that looms in the realm of blockchain magic. Fear not, for we shall demystify this attack using simple explanations and captivating examples!

💡 Key Ideas

  • Dark Sorcery: A 51% attack is like an evil spell cast by a group of powerful wizards who control more than half of the magical network, allowing them to manipulate the realm's records.

  • Rewriting History: With this wicked magic, the malevolent group can change past transactions and even spend the same magical coins twice, causing confusion and chaos.

  • Decentralization Defense: To fend off such an attack, the kingdom relies on decentralization, spreading the computing power among many adventurers to keep the magic secure.

  • Proof-of-Work Challenge: Some realms use tricky puzzles for validation, making the sorcerers work hard to alter the enchanted records.

  • Longevity Safeguard: The longer the kingdom's history, the more resistant it becomes to the dark magic, making it harder for sorcerers to corrupt the realm.

The Blockchain Kingdom

In the realm of blockchain, magical chains of encrypted data form a kingdom where adventurers record their enchanted transactions. Every adventurer, including you, can participate in maintaining and validating this blockchain.

The 51% Sorcery

Imagine a dark spell cast by a group of malicious wizards who hold more than 51% of the kingdom's computing power. This sorcerous group gains an unfair advantage, allowing them to control the kingdom's destiny.

The Challenging Enchantment

In this wicked scheme, the malevolent group can rewrite the blockchain's history, tamper with transactions, and even double-spend their magical coins. It's like a bewitched reality where they can make the realm believe in fraudulent potions.

The Struggle for Consensus

To protect the kingdom, blockchain relies on consensus among adventurers. Normally, honest wizards dominate, and the realm remains secure. However, the 51% sorcerers can override this consensus and seize control.

The Magical Defenses

Fear not, young adventurers! The blockchain kingdom has powerful enchantments to resist the 51% attack:

  1. Decentralization Charms: The more widely spread the computing power, the harder the attack becomes. A well-distributed network makes sorcery difficult.

  2. Proof-of-Work Shield: In some blockchains, adventurers must solve complex riddles to validate transactions. The majority sorcerers must overpower this defense, which is no easy feat.

  3. Altar of Time: The longer the blockchain, the more secure it becomes. Sorcerers must cast their malicious spells across a vast history, exposing themselves to detection.


As we conclude our magical quest through the realms of blockchain, may you, young wizards and sorcerers, grasp the essence of the 51% attack. Remember, it's a potent threat, but the enchantments of decentralization, proof-of-work, and time stand strong to safeguard the integrity of the kingdom's enchanted transactions. Let us continue our journeys, protecting and preserving the magic of the blockchain realm!