May 28, 2023
Proof-of-Work (PoW) is a consensus algorithm vital in securing and validating transactions in blockchain networks.
It stands as a foundational consensus algorithm in blockchain technology, responsible for securing transactions and maintaining the integrity of decentralized networks. In this comprehensive exploration of PoW, we will embark on a journey through its intricacies, shedding light on the roles of miners, the transaction process, and the mechanisms employed to fortify the network against malicious attacks.
Alice seeks to transfer 5 BTC to her friend Bob in the heart of a bustling digital bazaar. Eager to make the transaction, Alice creates a digital record containing her public key, a unique identifier associated with her account. You can consider the public key as your bank account number; others need it to send money to you. Similarly, Bob possesses his own public key, allowing for seamless identification within the blockchain network.
E.g., Alice's public key may look something like this:
and, Bob's public key may look something like this:
Let’s look at what a digital record consists of. It holds crucial information, including Alice's public key, Bob's public key, and the desired amount of 5 BTC. It serves as a digital representation of the transaction, capturing the essence of their exchange within the vast blockchain landscape.
Deep within the labyrinth of the blockchain, miners emerge as the stalwart guardians of the network's security and transaction validation. These diligent individuals collect unconfirmed transactions from various sources, including participants like Alice, who initiate transactions through their digital wallets.
Driven by the desire to contribute to the network's integrity, Miners can join the mining community. Becoming a miner typically requires specialized hardware, such as mining rigs, powerful graphics processing units (GPUs), and access to the blockchain network. Anyone with the necessary resources and technical acumen can partake in the mining process, adding their computational might to the collective effort.
Within the digital record, Alice's transaction details are embedded, awaiting the transformative power of cryptographic hash functions. Let's consider the example of Alice transferring 5 units of the BTC to Bob, resulting in the following transaction details:
Sender:Alice's Public Key:
Recipient:Bob's Public Key:
To ensure the security and integrity of the transaction, the block data, including the transaction details, is processed through a cryptographic hash function like SHA-256.
Block data is a collection of records, called transactions, which record the information about the exchanges of value or data within the blockchain network. A block data also has a timestamp, which shows when the block was created, and a cryptographic hash of the previous block, that connects the block to the rest of the blockchain .
A block data may have other information, depending on the specific blockchain protocol. For example, in Bitcoin, a block data has a version number, a nonce, a difficulty target, and a Merkle root. These elements are used for various purposes, such as validating the proof-of-work, adjusting the mining difficulty, and verifying the transactions.
Applying the SHA-256 hash function to this block data generates a unique hash value that serves as a digital fingerprint, uniquely representing the transaction within the blockchain.
For instance, let's assume the resulting hash for Alice's transaction is:7382a1f4ec85cdeabc83fd9a6a5509f63a1f72db7466746f8c2c7c3b1f2aef9d
Even a minute alteration in the transaction data, such as changing Alice's public key or the amount, would lead to a significantly different hash value. This property ensures that any tampering or unauthorized modification of the transaction will be detectable within the blockchain network.
As miners embark on their quest to discover a valid hash, they face the challenge of finding a nonce that, when combined with the remaining block data, produces a hash satisfying a specific criteria. This criteria is often represented as a target value, dictating the number of leading zeros expected in the resulting hash.
The target value is a number that shows how hard it is to mine a block. The smaller the target value, the more difficult it is to find a valid hash for the block. The target value comes from the difficulty, which is a way of measuring how much work is needed to mine a block. The difficulty changes every 2016 blocks (in Bitcoin) based on how long it took to mine the previous blocks. The aim is to make sure that blocks are mined every 10 minutes on average. The difficulty is stored in the block header as the nBits value, which is a short way of writing the target value.
The target value also acts as the highest possible value for a valid block hash. The block hash has to be smaller than or equal to the target value to be accepted by the network. This means the target value decides how many leading zeros the block hash needs to have. The more leading zeros, the smaller the block hash value, and the more challenging it is to find a valid hash.
For example, if the target value is0x00000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
,then the block hash needs to have at least 8 leading zeros to be valid. If the target value is0x000000000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
, then the block hash needs to have at least 12 leading zeros to be valid.
Imagine a target value that requires the hash to exhibit 10 leading zeros. Miners meticulously alter the nonce, repeating the process of hashing the block data with different nonce values until they uncover a nonce that yields a hash meeting the criteria.
For example, a miner begins with a nonce of 12345 and combines it with the block data. After applying the hash function, the resulting hash does not satisfy the criteria. Undeterred, the miner increments the nonce, trying new values like 67890, 98765, and beyond. The process continues until a nonce is discovered that, when hashed, produces a hash value with the desired number of leading zeros.
By persistently modifying the nonce and recalculating hashes, miners engage in a game of computational ingenuity, continuously striving to unearth the elusive golden nonce that unlocks the validation of the block.
Armed with their specialized mining rigs and computational power, miners dive into the electrifying frenzy of mining. Each miner races against time and competes with others to alter the nonce and recalculate hashes in the quest for the golden nonce.
In this vivid tale of computational prowess, miners dedicate their resources to performing countless hash calculations per second. Their mining rigs and GPUs hum with activity, as each miner seeks to be the first to discover the golden nonce that will grant them the opportunity to propose the next block to the network.
Amidst the exhilaration of mining, a miner finally uncovers the coveted golden nonce, generating a hash that satisfies the predefined criteria. With triumphant zeal, the miner broadcasts the block to the network, accompanied by the solution—the sacred nonce that unlocked the validation.
However, the network is designed to ensure consensus and prevent a single miner from monopolizing the rewards. Other miners, acting as validators, independently verify the block and its contents. They reapply the hash function to confirm the authenticity of the nonce and ensure its validity.
If the validation is successful, the block is embraced by the network and appended to the blockchain, marking another milestone in the decentralized journey. The validation process instills trust and prevents a single miner from falsely claiming the rewards for themselves. It is the collective effort of the mining community that upholds the network's integrity and fairness.
Proof of work is a way to secure and validate transactions in a blockchain network. It makes miners do hard calculations to find a valid hash for each block. The hash must follow a certain rule, which changes with the difficulty level and the target value. The difficulty level is updated regularly to keep a constant block creation rate. Proof of work stops malicious attacks and double-spending by making it expensive and hard to change or fake the blockchain data. Proof of work is the first and most popular consensus algorithm in blockchain, used by networks like Bitcoin, Ethereum, Litecoin, and others.
We have traversed the remarkable world of Proof of Work, witnessing the intertwining tales of miners, transactions, and cryptographic puzzles. The examples of public keys, transactions, hash values, and the pursuit of golden nonces have illuminated the intricate processes that underpin the security and trust in blockchain networks. As the blockchain ecosystem evolves, the legacy of Proof of Work endures, empowering decentralized networks with robust consensus and the promise of a secure digital future.
Subscribe to the newsletter to learn more about the decentralized web, AI and technology.