The immutability of blockchain is a fundamental characteristic that ensures once data has been added to the blockchain, it cannot be altered or deleted. This feature is crucial for the technology's ability to provide a secure and trustworthy system for recording transactions. Here’s a detailed explanation of why blockchain is immutable:
Cryptographic Hash Functions
Each block in a blockchain contains a unique cryptographic hash of the previous block, along with its own data and timestamp. This hash function is a one-way cryptographic algorithm that converts an input of any length into a fixed-size string of text, which acts as a digital fingerprint of the data. Any alteration to the data changes this hash. Since each block’s hash includes the hash of the previous block, changing any block would require recalculating the hashes of all subsequent blocks, making tampering evident and practically impossible[1][3][7][8].
Decentralized Consensus Mechanisms
Blockchain operates on a decentralized network of nodes, which must all agree on the validity of transactions through a consensus mechanism before they are added to the blockchain. Common consensus mechanisms include Proof of Work (PoW) and Proof of Stake (PoS). These mechanisms require that a majority of nodes agree on the transaction data, which helps prevent fraudulent alterations. Altering recorded data would require an attacker to control a majority of the network’s computing power, a feat that is highly impractical and costly due to the distributed nature of the network[1][5][6][8].
Economic and Computational Costs
Executing a successful attack, such as a 51% attack where an attacker gains control of the majority of the network's hash rate, involves enormous computational and economic resources. This includes acquiring sufficient hardware and electricity to outpace other nodes. The costs associated with such an attack often outweigh the potential benefits, acting as a deterrent against tampering with the blockchain[5][6][9].
Network Size and Security
The security and immutability of a blockchain improve as more nodes particip...
