Distributed ledger technology

Distributed ledger technology (DLT) refers to technologies that enable records or data to be shared, synchronized, and maintained across multiple participants or locations in a network without necessarily relying on a single centralized database. DLT can use distributed databases, cryptographic techniques, consensus mechanisms, and other technologies to maintain a shared record among participating entities.

Blockchain is a type of distributed ledger technology, but not all distributed ledger technologies use a blockchain structure.

Characteristics

Distributed ledger technology commonly involves:

multiple participating nodes or entities;
shared or synchronized records;
mechanisms for validating transactions or changes;
cryptographic techniques;
consensus or coordination mechanisms;
distributed data storage;
rules governing access and participation.

The specific characteristics vary among DLT systems.

Distributed ledger

A distributed ledger is a record of transactions or other information that is maintained across multiple participants in a network.

Unlike a conventional centralized database, a distributed ledger can distribute responsibility for maintaining and validating records among multiple entities.

A simplified representation is:

${Participant}_{1} \leftrightarrow Shared Ledger \leftrightarrow {Participant}_{2} \leftrightarrow {Participant}_{3}$

The precise architecture depends on the DLT system.

Nodes

A node is a computer or other network participant that maintains, processes, validates, or communicates information associated with a distributed ledger.

Depending on the system, nodes may:

maintain ledger records;
validate transactions;
participate in consensus;
transmit transactions;
verify data;
maintain network availability.

Not every node necessarily performs every function.

Consensus mechanisms

Distributed ledger systems may use consensus mechanisms to coordinate participants and establish agreement about the state of the ledger.

Examples include:

proof-of-work;
proof-of-stake;
Byzantine fault-tolerant mechanisms;
voting-based mechanisms;
other protocol-specific consensus mechanisms.

The choice of consensus mechanism affects factors such as security, performance, governance, and energy consumption.

Blockchain and distributed ledger technology

Blockchain is a specific form of distributed ledger technology in which records are generally organized into blocks that are cryptographically linked.

A simplified blockchain structure is:

${Block}_{1} \to {Block}_{2} \to {Block}_{3} \to \dots$

DLT is a broader category that can include systems using structures other than sequential blocks.

Therefore:

$Blockchain \subseteq Distributed Ledger Technology$

Permissioned and permissionless systems

DLT systems can differ according to who is permitted to participate.

Permissionless DLT

A permissionless distributed ledger generally allows participants to join the network and perform specified functions without requiring authorization from a central administrator.

Public blockchain networks such as Bitcoin are examples of permissionless distributed-ledger systems.

Permissioned DLT

A permissioned distributed ledger restricts participation or particular network functions to authorized entities.

Permissioned systems may be used by:

financial institutions;
businesses;
government organizations;
industry consortia;
other groups requiring controlled participation.

Public and private networks

DLT networks can also be classified according to the visibility and accessibility of their records.

A public network may allow broad access to ledger information, while a private network may restrict access to approved participants.

Permission and visibility are separate characteristics, and a DLT system can combine them in different ways.

Cryptography

Cryptography can be used in DLT systems to protect data and authenticate transactions.

Cryptographic techniques may provide:

data integrity;
authentication;
digital signatures;
transaction authorization;
secure communication.

The specific cryptographic mechanisms depend on the architecture of the distributed ledger.

Digital signatures

Digital signatures can be used to authenticate transactions and establish that a transaction was authorized using the appropriate cryptographic credentials.

A simplified transaction structure can be represented as:

$Transaction + Digital Signature \to Verification$

Successful verification does not necessarily establish that the underlying transaction is legally valid or that the information supplied by a participant is factually correct.

Smart contracts

Smart contracts are programs that can execute predefined instructions on certain distributed-ledger platforms.

They can automate processes such as:

payments;
asset transfers;
settlement;
contractual workflows;
issuance of digital assets.

Smart contracts are particularly associated with blockchain-based DLT systems.

Digital assets

DLT can be used to record and transfer digital assets.

Examples include:

cryptocurrencies;
tokens;
tokenized financial assets;
digital certificates;
other digitally represented rights or assets.

The legal and economic characteristics of an asset depend on its design and applicable laws.

Financial services

DLT has been explored and implemented in financial services for:

payments;
securities settlement;
clearing;
trade finance;
collateral management;
digital assets;
identity management;
transaction reconciliation.

Potential benefits include shared records, automation, and reduced duplication of data across participating institutions.

Electronic trading

Electronic trading systems can use distributed-ledger technologies for selected functions involving transaction recording, settlement, or post-trade processing.

DLT is not synonymous with electronic trading because most electronic trading systems do not require a distributed ledger.

Supply-chain management

DLT can be used to maintain shared records across supply-chain participants.

Potential applications include:

tracking goods;
recording provenance;
documenting transfers;
verifying transactions;
coordinating information between organizations.

The reliability of a distributed ledger depends on the accuracy of information supplied to the system.

Identity management

DLT can support some forms of digital identity and credential management.

Potential applications include:

identity verification;
digital credentials;
certificate verification;
decentralized identity;
authentication.

The use of DLT does not automatically guarantee privacy, accuracy, or legal recognition of identity information.

Healthcare

DLT has been proposed for applications involving:

medical records;
consent management;
health-data exchange;
credential verification;
pharmaceutical supply chains.

Implementation can be constrained by privacy, interoperability, security, and regulatory requirements.

Government applications

Government organizations can use or evaluate DLT for applications such as:

public records;
identity systems;
licensing;
land records;
supply-chain tracking;
document verification.

The suitability of DLT depends on the requirements of the particular public-service system.

Advantages

Potential advantages of distributed ledger technology include:

shared record keeping;
reduced duplication of records;
improved auditability;
cryptographic integrity;
automated processing;
increased transparency in appropriate systems;
reduced dependence on a single database administrator.

These benefits depend on the architecture, governance, and implementation of the DLT system.

Limitations

DLT can also involve limitations and risks, including:

scalability constraints;
transaction-processing delays;
interoperability problems;
governance challenges;
cybersecurity vulnerabilities;
privacy concerns;
regulatory uncertainty;
implementation costs;
energy consumption in some consensus mechanisms.

A distributed ledger is not necessarily more efficient or secure than a conventional database for every application.

Centralized databases and DLT

A conventional centralized database generally has a defined administrator or organization responsible for maintaining and controlling the database.

DLT distributes some or all of the responsibilities for maintaining and validating records among multiple participants.

The choice between centralized databases and DLT depends on factors such as:

trust relationships;
performance requirements;
governance;
data-sharing requirements;
security;
cost;
regulatory requirements.

DLT is therefore not inherently a replacement for conventional database technology.

Interoperability

DLT interoperability refers to the ability of different distributed-ledger systems to exchange information or assets.

Interoperability can be technically difficult because different systems may use different:

data structures;
consensus mechanisms;
identity systems;
transaction models;
governance rules.

Interoperability solutions may include specialized protocols, bridges, application programming interfaces, and other integration mechanisms.

Governance

DLT governance refers to the mechanisms through which decisions concerning a distributed-ledger network are made.

Governance can address:

protocol changes;
participant admission;
validation rules;
dispute resolution;
software upgrades;
network permissions.

Governance models vary from decentralized community-based arrangements to centralized organizational control.

Security

DLT systems use different combinations of cryptography, network architecture, consensus mechanisms, and access controls to protect ledger integrity.

Potential security threats include:

compromised private keys;
malicious network participants;
software vulnerabilities;
consensus attacks;
unauthorized access;
denial-of-service attacks;
vulnerabilities in connected applications.

The security of a DLT system depends on its complete technical and operational architecture.

Privacy

DLT systems can have different privacy characteristics.

Some systems provide publicly visible transaction records, while others restrict access to authorized participants.

Privacy mechanisms can include:

access controls;
encryption;
pseudonymous identifiers;
zero-knowledge proofs;
confidential transaction mechanisms.

Privacy requirements must be considered alongside transparency and auditability.

Importance

Distributed ledger technology provides an alternative approach to maintaining shared digital records among multiple participants. By combining distributed data storage, cryptography, consensus mechanisms, and programmable processes, DLT can support applications in financial services, digital assets, supply chains, identity management, and other areas where multiple parties need to coordinate information. Blockchain is one important form of DLT, but the broader category includes other distributed-ledger architectures.