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 uses the hashing power of the Bitcoin blockchain to enhance network security. By using delayed Proof of Work (dPoW), Komodo developers are able to protect not only their own network, but also any third-party blockchain that joins the Komodo ecosystem in the future. In fact, dPoW can be used to protect 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 was developed and implemented using the Zcash code base. By leveraging Bitcoin’s hash 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 results of the snapshot are then written to blocks on the Bitcoin network. Overall, this process creates a backup of the entire Komodo system, which is stored in the Bitcoin blockchain.

Technically, the notary nodes elected by the Komodo community write the block hashes of each dPoW-protected blockchain to the Komodo distributed ledger by executing transactions on the Komodo chain. By calling the OP_RETURN instruction, the notary nodes store a single block hash on 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. The network of each blockchain will still reach a consensus on each block. The notary node simply records the hash value of the block from the previous mining.

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

After the Notary Nodes have completed their operations on the Bitcoin blockchain network, Komodo's Notary Nodes will write the block data from the Bitcoin blockchain back to each protected chain. At this point, the network will not accept any reorganization operations that attempt to change the notarized block (or any block created before the Notary Nodes reached consensus).

Currently, dPoW is used in conjunction with Bitcoin, but it can be used as a security tool in any other blockchain that uses 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 cyber attacks such as Distributed Denial of Service (DDoS). In short, the PoW algorithm is a block of data that is very expensive to produce, but it is easy to verify 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 cryptographic problem in order to mine a new block. This process involves a lot of computing work and requires very expensive hardware and electricity. The mining process 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 solving difficult problems).

Therefore, one of the reasons why proof-of-work based blockchains are secure is that the process of mining involves very high capital investment. However, it is important to note that the security of PoW blockchains is directly related to the computing power (hash) 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 "resets" the consensus rules of the blockchain. For example, most PoW blockchains use the "longest chain rule". Therefore, every time the blockchain network confirms that blocks XXX and XX1 have been notarized, the longest chain rule starts from blocks XXX, XX2. The network will no longer accept a chain starting from blocks XXX, XX0 or before, even if it is the longest chain.


Summarize

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

If you want to learn more about Delayed Proof of Work, check out Komodo’s Blockchain Security Services page.