Unit
- Structure: A blockchain is a distributed ledger comprised of sequential blocks, each containing a batch of transactions. Each block references the cryptographic hash of the previous block, forming an unbroken chain.
- Blocks: A block typically includes a header (with timestamp, hash, previous hash) and a body (list of transactions). The first block is called the genesis block.
- Chaining: The cryptographic link ensures that altering any previous block would change its hash, breaking the chain and alerting the network to tampering.
- Decentralization: The ledger is replicated across many nodes (computers) in a peer-to-peer network. No single entity controls the blockchain, reducing counterparty risk.
- Consensus: Nodes agree on the state of the ledger through a consensus mechanism (e.g., Proof of Work). This eliminates the need for a central authority.
- Immutability: Once a block is added and confirmed, it is extremely difficult to reverse. This property is foundational for financial audit trails.
- Transparency: All transactions are visible to participants (depending on permission settings). In public blockchains, anyone can view the transaction history.
- Financial Use Cases: Blockchain enables faster cross-border payments, transparent supply chain finance, tamper-proof trade documents, and programmable money through smart contracts.
- Smart Contracts: Self executing agreements where the terms are written directly into code. They automatically enforce obligations when predefined conditions are met, removing the need for intermediaries and reducing settlement times in financial transactions such as derivative clearing and bond coupon payments.
- Permissioned vs Permissionless: Permissionless blockchains let anyone join the network and validate blocks, maximizing transparency. Permissioned blockchains restrict participation to approved entities, offering higher transaction speeds and data privacy, making them suitable for enterprise financial applications like interbank settlements and trade finance networks.
- Fork Types: Forks occur when the blockchain protocol is updated or disputed. Soft forks are backward compatible, while hard forks create a permanent chain split, sometimes leading to new assets. Forks allow networks to evolve but require careful coordination among stakeholders to maintain consensus and asset value.
- Scalability Challenges: Blockchains face a trilemma balancing security, decentralization, and scalability. Layer 2 solutions such as the Lightning Network process transactions off chain while inheriting security from the main chain. Sharding splits the network into smaller partitions to process transactions in parallel, increasing throughput for financial applications.
Financial Formula
Block Hash Function
Hash = SHA256(previous_hash + timestamp + nonce + merkle_root)
Hash = SHA256(previous_hash + timestamp + nonce + merkle_root)
Where:
- SHA256: The cryptographic hash algorithm used in Bitcoin and many blockchains.
- previous_hash: The hash of the preceding block, creating the chain.
- timestamp: Time when the block was created.
- nonce: A number varied during mining to achieve a hash below a target.
- merkle_root: A hash that summarizes all transactions in the block.
Quick Revision
- A blockchain is a distributed ledger of blocks linked by cryptographic hashes.
- Each block contains a header and a set of transactions.
- The chain ensures tamper evidence and historical integrity.
- Decentralization removes single points of failure and trust requirements.
- Consensus mechanisms allow network participants to agree on ledger state without a central party.