Proof-of-Proof (PoP)
The PoP consensus protocol allows blockchains to leverage the security of PoW consensus from other blockchains, creating a cohesive ecosystem. This means that the high level of security achieved by networks like Bitcoin, due to mining and a high hashrate, can be extended to other blockchains. The uniqueness of the PoP protocol lies in the periodic publication of data from one blockchain to another, which can be referenced in the event of network changes.
This ecosystem can be considered symbiotic with Bitcoin, as it indirectly promotes scalability by using its blockchain as a security mechanism. PoP offers a way to inherit the security of the Bitcoin network without direct involvement or approval from Bitcoin miners, and without relying on centralized organizations or “federated nodes.” Furthermore, PoP blockchains are not subject to technical restrictions.
The Core Idea of Proof-of-Proof
The core concept of PoP is that a PoP blockchain uploads data about its state to another blockchain (primarily Bitcoin, but theoretically it could be any PoW blockchain) to ensure its own security. This allows smaller blockchains to benefit from the high hashrate of a larger PoW blockchain, thus protecting an unlimited number of smaller blockchains.
In essence, the security of a PoP blockchain is guaranteed because a record of its state is embedded within the consensus of the larger blockchain. This means that the consensus of one network is spread to another in a certain sense.
CI and CP Blockchains
To understand how PoP works, it’s important to introduce a few concepts as described in the White Paper of VeriBlock, the developer of PoP:
- Consensus Inheriting (CI) Blockchain: A blockchain protected by PoP, which inherits PoW from another blockchain.
- Consensus Providing (CP) Blockchain: A blockchain with a high level of security, chosen so that the CI blockchain can inherit its PoW.
- Blockchain State Data: Information about the current state of a blockchain, such as the most recent block header, block hash, Merkle transaction root, etc.
- PoP Miner: A miner responsible for publishing blockchain state data from the CI blockchain to the CP blockchain.
Therefore, the PoP protocol introduces a new type of miner that periodically publishes the current state of the CI blockchain to the CP blockchain. These publications can be referenced in case of issues with the CI blockchain. PoP requires that the CI blockchain have a method for generating its own blocks, such as local PoW (without the need for high hashrate, as security is provided by the CP blockchain), PoS, etc.
How does Proof-of-Proof Mining Work?
PoP miners facilitate communication between CI and CP blockchains. They compete to ensure that their copy of the state of the PoP blockchain is included in the earliest block of the Bitcoin network.
In PoP mining, miners take the latest state data of the CI blockchain and publish it on the CP blockchain along with an identifier, which allows them to later receive compensation for their work. This is accomplished by creating a transaction on the CP blockchain that includes the state of the CI blockchain and the embedded identifier.
The PoP miner then waits for the transaction to be included in a block on the CP blockchain, and sends the proof of publication, including the necessary identifier to demonstrate their work, back to the CI blockchain in the form of a special PoP mining transaction. This transaction verifies that the state data of the CI blockchain has been successfully included in a block of the CP blockchain.
Who Uses PoP?
The Proof-of-Proof consensus protocol was developed by the VeriBlock team, who also implemented it in their own project. VeriBlock aimed to create a platform where users could build their own unique blockchain based on PoP, inheriting the security of the Bitcoin network.
However, VeriBlock did not gain widespread popularity, and Proof-of-Proof was unable to reshape the crypto landscape as it faced tough competition from sidechains and individual Layer 2 solutions.
Nevertheless, the idea of one blockchain assuming some workload from another has not been abandoned. The concept of modular blockchains, albeit in slightly different forms, remains popular and represents the same paradigm of symbiotic relationships between different blockchains.
Conclusion
Even if the crypto industry does not fully embrace the original concept devised by the VeriBlock team, the idea of Proof-of-Proof will continue to exist. This means that the PoP concept, as a significant milestone in the development of the modular paradigm, remains relevant and deserving of attention.