Public, Private, and Permissioned Blockchains – What do all these mean?

Blockchains have entirely transformed the way businesses operate. They come with various advanced features, from decentralisation to security and transparency to immutability.

That said, not all blockchains possess the same features. Based on these differences, they are classified into three main types.

Statista research indicates that as of 2021, the blockchain technology market value stood at 5.85 billion USD, projected to reach 1235.71 billion USD by 2030.

This article delves into public, private, and permissioned blockchains, highlighting their benefits and limitations.

Let’s get started.

What is a Public Blockchain?

Today, most blockchain networks operate on the public blockchain infrastructure. In this blockchain, users can read, write, audit, view the shared ledger, and participate in the consensus process by validating transactions.

Some examples of public blockchains include Bitcoin, Ethereum, Solana and Cardano networks.

Public blockchains work by incentivising network participants known as miners who solve complex cryptographic problems in return for rewards. Most public blockchains use the Proof-of-Work consensus mechanism. As PoW is supported primarily by global decentralised network participants, the mechanism makes the public blockchain decentralised in the true sense.

Advantages of a Public Blockchain

Public blockchains come with a variety of advantages.


Public blockchains are fully decentralised, and no single central authority dominates the network or controls the distributed ledger.


In a public blockchain network, all transactions are transparent as they can be viewed and audited by anyone (even those outside the network). Whenever any transaction occurs, the updated record of a copy of the shared ledger is available to each participant on the network. No tampering with any form is possible without the other network members remaining unaware.


Public blockchains are censorship-resistant, as no central authority or entity can shut down the network or tamper with any transactions.

Easy to access

Even compared to traditional banking services, public blockchains are more accessible as one needs a laptop or computer and a good internet connection.

Limitations of a Public Blockchain

The modern supply chain is a complex environment. It involves hundreds of individuals and organisations. According to Maersk, one shipment of refrigerated goods from East Africa to Europe involves more than 200 interactions. Hence, implementing blockchain in supply chain management is of paramount importance.

Blockchain-based supply chains are still a fresh concept for many. The following use cases will help you understand it better:


Most public blockchains require enormous power resources as they operate based on the Proof-of-Work mechanism. The network participants or miners need to expend excess energy using powerful computers to solve complex cryptographic equations. The energy-intensive nature poses a threat to the environment.

Of late, more blockchain networks are resorting to the Proof-of-Stake method, which involves staking cryptos to process the transactions and is, therefore, more eco-friendly.

Easily traceable transactions

Though the identity of network participants remains anonymous, a user’s transactions are traceable. In other words, if a user’s wallet address of a network participant gets linked to the user, other members in the network could be able to trace the history of that user’s transactions, amount of cryptocurrency, etc., as the shared ledger is publicly viewable.

What is a Private Blockchain?

In contrast to public blockchains, private blockchains refer to those invitation-based networks, where a central entity decides who must be included in the network. In addition, the entity also assigns roles to sure participants, granting them mining privileges or letting them participate in blockchain transactions. Most importantly, this central entity holds the power to view, edit, delete, and override the existing transactions. This aspect primarily differentiates private blockchain from public blockchain, as the former lacks censorship-resistance property.

Private blockchains are the most sought-after option for businesses or large corporations that want to have their data in isolation, away from the public. Transactions on a private blockchain must also be validated by a set of protocols implemented by the network validators. Some examples of private blockchains include the Morpheus network, a supply chain and logistics network, and Patientory, a medical supply chain app Ethereum-based.

Advantages of a Private Blockchain

Private blockchains come with a variety of advantages.

Highly secure

Private blockchains involve participants who are invited by the central entity. As a result, there’s little possibility of more people with malicious intent becoming a part of the network. That makes them more secure than other blockchains.

Higher transactions per second

Private networks are usually much smaller than public blockchains as they emphasise limited access. Consequently, they offer better throughput and execute transactions faster due to higher network availability.

More Trustworthy

In contrast to public blockchains, private ones have fewer participants. Moreover, as they are used mainly by enterprises or business organisations, there’s no anonymity for participants. Every participant’s identity in the network is known.

Increased Scalability

Private blockchains are managed by a central entity that decides on the number of network participants, who must be included, and such. Networks with fewer users and transactions perform better with increased scalability. That said, private blockchains can enforce these features more easily than public blockchains.

Limitations of a Private Blockchain

Lack of Immutability

Unlike public blockchains, private blockchains are not immutable. The central entity controls the shared ledger so it may tamper with the transaction records and other on-chain data.

Lack of Decentralisation

The private blockchains are not truly decentralised. The shared ledger is under the control of the central entity, making it a closed database.

What is a Permissioned Blockchain?

The third category of blockchains is the permissioned or consortium blockchain. As the name suggests, they need participants to be invited by the network operator, who grants the permissions. Unlike private blockchains that allow only known participants to join, permissioned blockchains allow anyone permitted by the network operator to be a part of it. They aren’t private blockchains, but they provide an additional security layer that lets only identifiable participants execute specific on-chain processes.

Compared to Private and Public blockchains, Permissioned blockchains are less popular. They are usually preferred by organisations that look for an additional layer of control, identity maintenance, and permission management features. Some examples include IBM Food Trust, a food supply chain verification system, and Ripple, a global payment platform.

Permissioned networks have the same blockchain technology underpinning them, similar to private and public blockchains. The only difference lies in the access control layer, which allows the network operator to grant permissions of varying levels and assign different roles to the users.

Advantages of a Permissioned Blockchain

Improved performance

In comparison to public blockchains, permissioned networks are less “heavier” as they are not open to the public. This implies there’s less on-chain data causing network clogging. This reduces the strain on the network, enhancing its speed, scalability, and overall performance.


Similar to private blockchains, these are managed by a central entity that makes bringing changes and implementation of upgrades or new functionalities to the network relatively easier.

Highly Customizable

Among the three blockchains, the permissioned blockchains are the most customisable. With the help of the permission management feature, they let the network operator invite and assign various roles to different participants.

Different degrees of decentralisation

Permissioned blockchain allows network operators to decentralise the network to varying levels. They can be partly decentralised or completely centralised as well.

Limitations of a Permissioned Blockchain

External Data Storage

Sometimes, permissioned networks require external storage space. However, the decentralised storage methods used by public blockchains may not be employed here as there might be variation in the degree of decentralisation. This, in turn, puts the security and integrity of the on-chain data at risk.

Inconsistency in Security

The security of permissioned blockchains depends on the consensus mechanism and the participants in the network. That said, participants with malicious intent could prove detrimental to the network’s security. In addition, these networks require some central regulation, which increases the risk of manipulation compared to public blockchains.

Final thoughts

Public blockchains for decentralisation, Private blockchains for scalability, and Permissioned blockchains for customisability.

In essence, all three blockchains have their own merits and demerits. The article discusses that their usability and scope depend on various factors.

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