Is Blockchain Secure?

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Blockchain is based on cryptography, a highly complex system of encoding messages. This makes it hard for a third party to decipher the encrypted message except for the intended recipient.

Cryptography serves as the bedrock for blockchain technology, and the framework requires miners or computer networks to solve complex mathematical puzzles to add blocks of transactions to the Blockchain.

Once the puzzle is solved, and the data is added to a previous block, it is considered immutable, which means no one can change or alter it. This is because each block has its unique hash, a set of variables that distinguishes it from the others. The hash is sent to all network validators, and each node has a valid copy of the block.

Suppose some malicious software tries to change this transaction block by introducing a modified hash to the network. In that case, the network validators will compare it to their copy and remove the illegitimate block from the chain.

A change can only be implemented if all participating nodes on the network reach a consensus.

Another option for modifying the blockchain is through a 51% attack.

The 51% attack occurs when a single entity controls more than 50% of the network’s computing resources. In theory, this allows the entity to revise previous transactions added to the blockchain. A 51% attack is highly unlikely on a network like Bitcoin due to the high level of decentralized node verification structure in place.