Delayed Proof of Work (dPoW) is a security mechanism designed by the Komodo project. Basically, it is a modified version of the Proof-of-Work (PoW) consensus algorithm that leverages the hashing power of the Bitcoin blockchain to enhance network security. By using Delayed Proof of Work (dPoW), Komodo developers will be able to secure not only their own network, but also any third-party blockchains that join the Komodo ecosystem in the future. In fact, dPoW can be used to secure any independent blockchain project developed using the UTXO model.

How does Delayed Proof of Work (dPoW) work?

Taking Komodo as an example, the dPoW security mechanism is developed and implemented using the Zcash code base. By utilizing Bitcoin’s hashing power, it achieves zero-knowledge privacy proof and improves network security.  

Every ten minutes, the Komodo system takes a snapshot of the blockchain network. The result of the snapshot is then written to a block on the Bitcoin network. Overall, this process creates a backup of the entire Komodo system that is saved on the Bitcoin blockchain.  

Technically speaking, notary nodes elected by the Komodo community write the block hash of each dPoW-protected blockchain into the Komodo distributed ledger by executing transactions on the Komodo chain. . By calling the OP_RETURN instruction, the notary node stores a single block hash onto the Komodo chain.

The reason why the notary node chooses a snapshot execution time of ten minutes is to ensure that the entire network recognizes the validity of the block. Each blockchain's network will still reach consensus on each block. The notary node simply records the block hash from the previous mine.

Next, the notary node writes the hash from the Komodo blockchain into the Bitcoin ledger. This step can also be accomplished by executing a Bitcoin transaction and writing the data to Bitcoin’s blockchain using the OP_RETURN instruction.

After the notary node completes the operation of the Bitcoin blockchain network, Komodo’s notary node will write the block data from the Bitcoin blockchain back to each protected chain. At this time, the network will not accept any reorganization operations that attempt to change the notarized block (or any block created before the notarized nodes reached consensus).

Currently, dPoW is bundled with Bitcoin, but it can be used as a security tool in any other blockchain using the UTXO model.

Proof of Work (PoW) and Delayed Proof of Work (dPoW)

One of the main goals of the Proof of Work (PoW) algorithm is to maintain network security and prevent network attacks such as distributed denial of service attacks (DDoS). In short, the PoW algorithm is very expensive to produce data blocks, but it is easily verified and is an important element in the mining process.

The mining design in PoW-based blockchains is very demanding. Miners need to solve a complex cryptography question to mine a new block. This process involves a lot of computational work and consumes very expensive hardware and electricity. The process of mining not only protects the network from external attacks, but also verifies the legitimacy of transactions and generates new digital currency (as a reward for miners for solving puzzles).  

Therefore, one of the reasons why proof-of-work-based blockchains are very secure is that the mining process involves very high capital investment. However, it is important to note that the security of PoW blockchains is directly related to the computing power (hashing) used for them, which means that small blockchain networks are not as secure as large blockchain networks.  

Unlike PoW, dPoW is not used to reach consensus on new blocks and is therefore not considered a consensus algorithm. It is a security mechanism implemented outside of the PoW consensus rules. DPoW makes it impossible for notarized blocks to be reorganized, which means it makes the blockchain more secure and resistant to 51% attacks.

In fact, every time a block is notarized, dPoW will "reset" the consensus rules of the blockchain. For example, most PoW blockchains use the "longest chain rule". Therefore, whenever the blockchain network confirms that blocks XXX and XX1 have been notarized, the longest chain rule will start from blocks XXX, XX2. The network will no longer accept chains starting from block XXX, XX0 or before, even if it is the longest chain.

Summary

The delayed proof-of-work security mechanism allows frequent backups to be performed to ensure that the system After a failure or intrusion, the entire network's data can be quickly restored. If an attacker wanted to successfully cause lasting damage, he would also have to shut down the Bitcoin network and destroy all snapshots backed up in the Bitcoin blockchain.  

If you would like to learn more about delayed proof-of-work, check out Komodo’s Blockchain Security Services page.