Private vs. Public Blockchain: What's the Difference?

Wondering about private vs. public blockchains? Do you need a permissioned blockchain, or is permissionless the way to go? Here's everything you need to know.

What are the four types of blockchain? The four types of blockchain are:

• Public Blockchain: Permissionless; anyone has access

• Private Blockchain: Closed network

• Permissioned Blockchain: Private, open, or closed networks with role-based controls

• Hybrid Blockchain: A combination of private and public blockchain

What Is the Blockchain?

Blockchain technology is a decentralized, irreversible ledger for record-keeping that doesn't require the participation or management of a central entity or organization.

The blockchain was invented as part of Bitcoin. The whitepaper, written by the pseudonymous Satoshi Nakamoto, defined the ledger as a system of cryptographically signed blocks of data that the collective computing power of the network would verify and place into an immutable record. This was seen as the solution to the "double spend" problem hindering the development of digital cash, and it served as the basis for the Bitcoin cryptocurrency.

In terms of the original blockchain, the process of exchange works as follows:

1. One user transfers a set number of bitcoins to another user.

2. The information related to that transaction (the users, timestamps, wallet addresses, etc.) is bundled into a "block" that is encrypted and cryptographically signed.

3. Blocks are bundled together, and nodes in the network (called "miners") donate CPU power to solve the equation confirming those blocks' signatures.

4. Once verified, the transactions are considered legitimate and appended to the end of the ledger.

5. The update is pushed to each network participant, all of whom maintain their own copy of the ledger.

Hence, the blockchain is literally a chain of blocks representing data about network activity.

Blockchain offers several critical benefits:

• Decentralization: The blockchain removes the need for centralized servers to store data. Instead, data is collectively stored across blockchain participants, providing greater resilience against attacks on central weak points.

• Immutability: The blockchain ledger cannot be changed without the collective work of the network or, in the case of private chains, the permission of a governing organization. This makes the blockchain especially resilient against fraud.

• Extensibility: The original blockchain was intended to govern token exchange, and many crypto chains still serve that function. Modern innovations like smart contracts have extended the blockchain to support decentralized automated agreements and application-layer logic.

What Are the Different Types of Blockchain?

While different implementations of blockchain technology share general similarities, there are meaningful differences worth understanding.

The main types of blockchain include the following:

• Public: The most widely known type of blockchain. Public blockchains are fully decentralized and user-operated. They are also permissionless, meaning anyone can join at any time without authorization from a governing body. Bitcoin is the most prominent example: completely decentralized, maintained through network nodes, with no central entity in control.

• Private: The opposite of a public chain. Private blockchains require users to have network access, typically through identity authentication, and to follow chain-specific rules to participate. A governing body or managing organization dictates the terms of access, mining capabilities, and what the blockchain stores.

• Permissioned: A hybrid of public and private. A control mechanism is in place, but additional role-based permissions allow different users to perform different types of actions on the chain.

These types aren't mutually exclusive. An application could use a private, permissioned chain to maintain security while assigning different permission levels across the system.

Benefits of Private Blockchain Technology

As more businesses adopt blockchain technology, they are discovering meaningful advantages across industries like finance, cloud computing, and identity management.

Some of the key benefits of a private blockchain include the following:

• Decentralization: Central servers serve as points of failure and attack. If a server storing passwords is compromised, all those passwords are exposed. With a private blockchain, there is no single location where all credentials can be stolen; no single node is a central point of failure.

• Development and Extensibility: With smart contracts and other emerging technologies, along with the fundamentally open-source nature of the underlying tech, blockchain systems can be modified to fit a company's specific needs.

• Transparency: Any transaction, user activity, or attempted breach is automatically appended to the ledger, permanently recorded. Because these systems are immutable and irreversible, they serve as an effective backbone for environments with strict auditing requirements.

• Ownership: Private, permissioned blockchains can be configured to leave data ownership in the hands of users rather than central businesses. Personally identifiable information can remain under user control, with only the minimum necessary data shared for processes like authentication or authorization. This is attractive to users and helps both users and organizations address real concerns around third-party data collection.

Decentralized Identity Management with 1Kosmos

One of the core challenges of enterprise identity management is that most systems rely too heavily on centralized servers, which create honeypots for attackers while removing identity control from users.

1Kosmos leverages a permissioned blockchain to decentralize identity management, storing information on devices rather than central servers. This approach supports identity proofing, passwordless login, and streamlined user experiences in a single platform.