Public permissioned blockchain A Framework for Enterprise

A public permissioned blockchain is a hybrid model that incorporates elements from both public and private blockchains. The consensus architecture of a public permissioned blockchain network combines elements from both public and private blockchains to achieve a balance between openness, security, and efficiency

Key Features of Public Permissioned Blockchain

Like public blockchains (e.g., Bitcoin, Ethereum), a public permissioned blockchain allows anyone to view and audit the data stored on the blockchain. This transparency ensures accountability and trust among participants.
Similar to private blockchains, only authorized nodes (participants) can validate transactions. This controlled access ensures that only trusted entities can participate in the consensus process, enhancing security and reducing the risk of malicious activity.
By restricting transaction validation to a set of authorized nodes, public permissioned blockchains can achieve higher efficiency and scalability compared to fully decentralized public blockchains, which often suffer from slower transaction speeds due to their extensive validation processes

Advantages of Public Permissioned Blockchain

Combines the openness of public blockchains with the control of private blockchains, allowing for a transparent system where data is accessible to all, but transaction processing and validation are managed by a select group.
Restricting the validation process to authorized nodes reduces the likelihood of malicious attacks and enhances the overall security of the blockchain.
By limiting the number of nodes involved in transaction validation, the blockchain can handle a higher volume of transactions more efficiently, addressing scalability issues often faced by public blockchains.
The transparency of a public permissioned blockchain ensures that all transactions are visible and auditable by anyone, fostering trust among participants. At the same time, the permissioned nature ensures that only credible entities can validate transactions, ensuring accountability.

Consensus Architecture

Nodes Types

--> Permissioned Nodes: Only selected, authorized nodes are allowed to participate in the consensus process. These nodes are typically vetted and trusted entities.

--> Observer Nodes: Any entity can run an observer node to view the blockchain data and verify transactions, but they do not participate in the consensus process.

Consensus Mechanism: The consensus mechanism used in public permissioned blockchains often combines features of both traditional public blockchain consensus protocols (like Proof of Work or Proof of Stake) with private blockchain protocols (like Practical Byzantine Fault Tolerance - PBFT). Common mechanisms include

--> Delegated Proof of Stake (DPoS): Token holders elect a small number of delegates to validate transactions and create new blocks. This maintains a degree of decentralization while improving efficiency.

--> PBFT (Practical Byzantine Fault Tolerance): A smaller group of pre-selected nodes validate transactions. This mechanism is highly efficient and can process transactions quickly but requires trusted validators.

Validation and Finality

--> Transactions are proposed by permissioned nodes and validated by a consensus protocol, ensuring that only authorized nodes can create and approve blocks

--> Finality is achieved faster than in typical public blockchains because the number of nodes involved in validation is limited, reducing the time and computational power required to reach consensus.

Governance

--> A governance framework dictates how nodes are added or removed, how consensus rules are updated, and how disputes are resolved.

-->Governance can be on-chain (using smart contracts to automate processes) or off- chain (through meetings and agreements among stakeholders).

Consensus Mechanism Process:

Transaction Proposal:Users submit transactions to the network. These transactions are propagated to all nodes in the network.
Transaction Validation: Permissioned nodes validate the transactions based on predefined rules and protocols. Invalid transactions are discarded.
Block Creation:Once a set of valid transactions is collected, a permissioned node (depending on the consensus mechanism, it could be the next in line, a randomly selected node, or an elected delegate) creates a new block containing these transactions

Consensus Agreement:

-->The proposed block is broadcast to other permissioned nodes, which must reach an agreement on its validity. In PBFT, for example, nodes go through several rounds of communication to agree on the block.

-->If a supermajority (often two-thirds) of nodes agree, the block is added to the blockchain.

Block Finality and Propagation Once a block is added, it is considered final and is propagated across the network. Observer nodes update their copies of the blockchain to include the new block.

Integrating Public and Private Blockchains:

Interoperability Solutions: Implementing interoperability solutions such as cross-chain communication protocols can enable seamless interaction between public and private blockchains. This allows assets and data to move freely and securely between different blockchain ecosystems.
Consortium Blockchains: Forming consortium blockchains where multiple organizations collaboratively manage a shared ledger can leverage the benefits of both public and private blockchains. This model maintains transparency and decentralization while ensuring control and security through permissioned access.
Layered Architecture:Adopting a layered architecture where a public permissioned blockchain acts as the main chain, and various private sidechains handle specific tasks or applications can optimize performance and scalability. This allows for efficient processing while maintaining overall transparency.
Smart Contracts and Oracles:Utilizing smart contracts and oracles can bridge the gap between public and private blockchains, enabling automated, trustworthy transactions and data sharing across different blockchain networks.

Security and Efficiency Considerations:

Sybil Resistance:The network uses permissioned nodes to mitigate the risk of Sybil attacks, where an attacker could create multiple fake identities to gain control.
Efficiency: Limiting the number of nodes involved in the consensus process enhances efficiency and scalability, allowing the network to process a higher volume of transactions with lower latency.
Transparency and Auditability:While transaction validation is restricted, the entire blockchain remains transparent and auditable by anyone, ensuring accountability and trust.

Example Use Cases:

Supply Chain Management:Ensures transparent tracking of goods while maintaining control over who can validate the transactions.
Financial Services: Allows for transparent yet controlled transaction processing among financial institutions.
Government and Public Sector:Facilitates transparent public records with controlled access for data entry and validation.

By adopting these strategies, organizations can create a robust blockchain ecosystem that harnesses the transparency, trust, and decentralized nature of public blockchains along with the security, control, and efficiency of private blockchains.

By combining these elements, a public permissioned blockchain can provide a balanced and effective consensus architecture suitable for various applications requiring both transparency and controlled participation