Lesson 1 of 7 · All lessons in this module
- Distributed ledgers, blockchains and their financial usesVideo lesson
- Proof of work, proof of stake and network types
- Types of digital assets: cryptocurrencies and tokens
- Digital assets versus traditional financial assets
- Direct investment: wallets, exchanges and their risks
- Indirect vehicles, asset-backed tokens and DeFi
- Risk, return and diversification of digital assets
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Lesson 1 of 7 · 13 min
Distributed ledgers, blockchains and their financial uses
A distributed ledger is one shared database that every participant holds a matching copy of; a consensus mechanism and cryptography keep it accurate, which can make record keeping, ownership transfer and post-trade processing faster and more transparent, at the cost of energy use and some security and privacy risk.
In short
- A distributed ledger is a database copied across a network of participants (nodes); each copy is a verified record of all current and past transactions.
- Three building blocks: the digital ledger, a consensus mechanism to confirm new entries, and a participant network.
- Consensus = validating a transaction, then agreeing on the ledger update. The result is a record that is close to immutable, yet visible to participants in near real time.
- Cryptography protects identities and data; smart contracts are programs that self-execute when pre-agreed conditions are met.
- A blockchain records transactions in blocks, each linked to the previous one by a cryptographic hash.
- Financial uses: creating digital assets, tokenization of real assets, faster post-trade clearing and settlement, and compliance. Drawbacks: high energy use and possible security and privacy breaches.
One ledger, many copies
A bank keeps its own private books; when two banks trade, each updates its own records and they reconcile later. A distributed ledger replaces those separate books with one shared database. Every participating computer, or node, holds a matching copy, so each copy is a full, verified history of the transactions on the network.
Distributed ledger technology (DLT) has three basic elements: the digital ledger itself, a consensus mechanism that decides which new entries are accepted, and the network of participants that hold copies. Because there is no single master copy, ownership of an asset can be created, exchanged and tracked peer to peer (P2P), without a central record keeper.
The consensus mechanism is how the nodes agree on the current state of the ledger. It usually has two steps: the transaction is validated, then the network parties agree to update the ledger. Once both steps are done, the entry is, for practical purposes, immutable (it cannot be changed), yet every participant can see it almost immediately.
Think of a shared spreadsheet that thousands of people hold a copy of, where a new row only appears in everyone's copy after the group agrees it is valid. Faking a row would mean changing most of the copies at once.
Cryptography, smart contracts and the blockchain
Cryptography is an algorithmic way of encrypting data so it is useless to anyone not authorised to read it. DLT uses cryptographic proofs to check who participants are and to protect the data, which gives the network its security and keeps the database intact.
DLT can also host smart contracts: computer programs that carry out an agreement automatically once pre-specified terms are met. A derivative could pay out the moment its trigger is hit, or collateral could move to a lender the instant a borrower defaults, with no back office in between.
A blockchain is the best-known form of distributed ledger. Transactions are grouped into blocks; each block holds a batch of transactions plus a secure link, called a hash, to the block before it. The blocks form a chain, so changing an old entry would break every link after it. A new block joins the chain only after the consensus mechanism confirms both the transactions and the order of the history before them.
What DLT can do for finance, and what it costs
The main financial applications are: (1) creating digital assets such as cryptocurrencies; (2) tokenization, recording ownership rights to physical assets such as property, art or commodities on a ledger, so the title and its full history live in one digital record; (3) streamlining post-trade clearing and settlement, where near-real-time verification, reconciliation and settlement can cut the time, cost and complexity of today's multi-step processes; and (4) compliance, where automation, smart contracts and identity checks make reporting and monitoring easier.
The benefits come from the design: greater accuracy, transparency and security of records, faster transfer of ownership and direct P2P dealing.
The costs are real too. DLT is not fully secure: privacy and data-protection breaches are possible. And the computation needed to validate transactions, especially under proof of work (next lesson), uses massive amounts of energy. DLT is therefore not an energy-efficient way to keep records.
| Benefits | Drawbacks |
|---|---|
| Accurate, transparent, secure records | Not fully secure: privacy and data breaches possible |
| Faster transfer of ownership; P2P dealing; smart contracts | Validation can need huge computing power and energy |
| Near-immutable shared history; no reconciliation | Hard to undo a wrong entry once accepted |
Worked examples
Example 1 Settlement with and without a shared ledger
Hallström Bank in Stockholm sells a block of corporate bonds to Kowloon Asset Management. Today, each side, a custodian and a central depository all keep separate records that must be matched before settlement two days later. How could a distributed ledger change this?
Example 2 Why rewriting history is hard
A dishonest participant wants to change a transaction recorded ten blocks ago so that a payment appears never to have happened. Why does the structure of a blockchain make this difficult?
Example 3 Spotting a tokenization use case
A Lisbon gallery sells paintings that change hands every few years. Each sale needs experts to verify ownership and authenticity from paper certificates. Which DLT application addresses this, and how?
On the exam
Expect definitions (distributed ledger, consensus mechanism, smart contract, blockchain, hash), the order of steps in adding a block, and 'which is not a benefit' items where energy efficiency or easy integration is the wrong answer.
- Calling DLT energy efficient. Validation, especially under proof of work, needs very large amounts of computing power and energy.
- Thinking a distributed ledger has one master copy held by an administrator. Every node holds a matching copy.
- Confusing a smart contract with a legal paper contract stored online. It is code that executes itself when its conditions are met.
- Saying DLT is fully secure. Records are hard to alter, but privacy and data breaches remain possible.
Check yourself
Q1Which of the following is least likely a benefit of distributed ledger technology?
Q2The process by which nodes on a DLT network agree on a common state of the ledger is the:
Q3A program on a blockchain that automatically transfers collateral to a lender as soon as a borrower misses a payment is best described as a:
Q4In adding a transaction to a blockchain, which step most likely comes immediately before the new block is linked to the chain?
Q5A DLT application best suited to simplifying ownership verification of physical assets such as real estate is:
Answer the 5 questions: +10 XP for each one you get right first time.
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