How does blockchain keep data secure and unalterable? While many associate blockchain with cryptocurrencies like Bitcoin, its real power lies in its ability to lock data immutably. Discover how cryptographic hashing, consensus mechanisms, and decentralised networks work together to protect data integrity in this deep dive into blockchain security.
Table of contents:
- Introduction
- Understanding Blockchain and Data Blocks
- How is a block of data locked on a blockchain?
- Security implications of block locking
- Final thoughts
Blockchain technology has transformed how data is stored and managed, offering security and transparency through decentralised networks. But how does blockchain ensure that once data is recorded, it remains secure and unalterable?
Although some people know blockchain technology only because of its connection to cryptocurrencies like Bitcoin or Ether, it is simply a digital system that stores linked and verified records.
One of the key benefits of this digital “ledger” is that it cannot be easily changed or tampered with, and it can be updated instantly online. These features make blockchain technology useful for checking data, controlling access to information, and keeping identities secure. These are some of the most common ways in which blockchain is used.
Since blockchain is a shared record-keeping system, it includes special security measures that prevent data blocks from being changed. This helps to keep information safe and unaltered. Many blockchain development companies use this feature to strengthen security for their clients.
But how is a block of data locked on a blockchain? And what does it actually mean to lock data on a blockchain?
Understanding Blockchain and Data Blocks
To grasp how data is locked on a blockchain, it is essential to understand the fundamental components that make up this technology.
What is a blockchain?
A blockchain is a distributed ledger that records transactions across multiple computers. It ensures transparency, security, and immutability, making it highly reliable for financial transactions, supply chains, and digital identities. Once recorded, data on a blockchain cannot be modified without altering every subsequent block, which is computationally impractical.
Blockchain operates on a decentralised network of nodes (computers) that maintain and validate transaction records. Each node possesses a complete copy of the blockchain, ensuring data integrity and preventing unauthorised modifications. Transactions are grouped into blocks and linked together in a chronological order, forming an immutable chain.
What is a block?
A block is a fundamental unit of data storage in a blockchain. It contains a list of transactions that have been validated by the network. Each block is added sequentially to form a chain, ensuring chronological order and data integrity.
The time taken to generate a new block varies depending on the blockchain network. For example, Bitcoin takes approximately 10 minutes per block, while Ethereum takes about 15 seconds. This block time impacts transaction speed, security, and network efficiency.
Data blocks serve as secure containers that store transactions and maintain the integrity of the blockchain. Each block strengthens the previous block by linking to it, creating an immutable ledger that prevents fraudulent modifications.
A block typically contains:
- A list of transactions recorded during a specific time frame.
- A timestamp to indicate when the block was created.
- A hash that uniquely identifies the block’s content.
- A nonce, which is a number used in cryptographic operations.
- A previous block hash, which links the current block to the previous one.
Key components of a block
The hash of each block is crucial in maintaining blockchain integrity. If any transaction or data in a block is altered, the hash of that block changes. This invalidates the subsequent blocks, alerting the network to potential tampering attempts. Each block contains essential elements that ensure its security and authenticity:
- Transaction Data – Contains details such as sender, receiver, and the amount transferred.
- Hash – A unique alphanumeric string generated through a cryptographic function, ensuring the block’s authenticity.
- Nonce – A number used in proof-of-work consensus to generate a valid hash.
- Previous Block Hash – Links the block to its predecessor, ensuring continuity in the blockchain.
How does a block of data on a blockchain get locked?
The process of locking a block involves multiple steps, ensuring security and integrity.
- Transaction creation and verification: Every transaction on a blockchain is digitally signed to authenticate the sender and prevent unauthorised modifications. Transactions are verified using cryptographic techniques. When a user initiates a transaction, a digital signature is created using their private key. This ensures that only the sender can authorise transactions from their wallet. The network nodes then validate the transaction by checking the sender’s public key and available balance.
This process involves:
- Creating a transaction – Users initiate transfers using digital wallets, specifying details like the recipient and amount.
- Verifying a transaction – Nodes in the network validate transactions by checking sender balances and confirming legitimacy.
- Broadcasting a transaction – Verified transactions are shared with all nodes to ensure transparency and prevent fraud.
- Block creation and hashing: Once transactions are verified, they are grouped into a new block. A miner or validator compiles verified transactions into a block. The block data is then processed through a hashing algorithm (e.g., SHA-256 in Bitcoin), generating a unique hash that represents the block. If any data in the block is modified, the hash will change, ensuring tamper resistance.
- Grouping transactions – Transactions are collected and structured into a block.
- Generating a hash – A cryptographic function processes the block’s data, producing a unique hash. Any change in data alters the hash, revealing tampering attempts.
- Nonce calculation – In proof-of-work systems, miners solve a cryptographic puzzle by finding a nonce that meets difficulty criteria.
- Consensus mechanisms: Before a block is added to the blockchain, nodes must reach consensus. The two most widely used mechanisms are:
- Proof of Work (PoW) – Miners compete to solve complex puzzles, with the first to find the correct nonce earning the right to add the block.
- Proof of Stake (PoS) – Validators are chosen based on the amount of cryptocurrency they hold, reducing energy consumption compared to PoW.
Other mechanisms include:
- Byzantine Fault Tolerance (BFT) – Used in private blockchains, requiring a majority agreement to validate a block.
- Delegated Proof of Stake (DPoS) – Token holders elect representatives to validate transactions.
- Block verification and network acceptance: Once a block is proposed, nodes independently verify its validity. This involves:
- Transaction validity checks – Ensuring all transactions comply with blockchain rules.
- Hash integrity checks – Recomputing the hash to confirm consistency.
- Chain consistency checks – Verifying that the block correctly links to the previous block.
- Adding the block to the blockchain: After successful verification, the block is officially added to the blockchain:
- Updating the ledger – All nodes update their copies of the blockchain.
- Ensuring immutability – Once added, altering a block would require modifying all subsequent blocks, making changes impractical.
Security implications of block locking
- Immutability and tamper resistance: Blockchain’s structure prevents data alterations, as modifying one block disrupts the entire chain. This feature ensures integrity and security.
- Cryptographic hashing for data integrity: Each block’s hash functions as a digital fingerprint, verifying its authenticity. If any data is altered, the hash changes, exposing unauthorised modifications.
- Decentralisation and security: By distributing data across multiple nodes, blockchain eliminates central points of failure. Even if a node is compromised, the system remains secure.
Final thoughts
Blockchain technology provides a secure and transparent way to store and manage data. The process of locking data involves transaction verification, cryptographic hashing, and consensus mechanisms, ensuring security and immutability.
While scalability and energy consumption remain challenges, ongoing innovations aim to enhance blockchain’s efficiency and sustainability. As the technology evolves, its applications across industries will continue to expand, reinforcing its role as a trusted digital ledger.
Shikha Negi is a Content Writer at ztudium with expertise in writing and proofreading content. Having created more than 500 articles encompassing a diverse range of educational topics, from breaking news to in-depth analysis and long-form content, Shikha has a deep understanding of emerging trends in business, technology (including AI, blockchain, and the metaverse), and societal shifts, As the author at Sarvgyan News, Shikha has demonstrated expertise in crafting engaging and informative content tailored for various audiences, including students, educators, and professionals.
