Delegated Proof of Work (dPoW) is a security mechanism developed by Komodo. It is basically a modified version of the Proof of Work (PoW) consensus algorithm that uses the hash power of the Bitcoin blockchain as a way to improve the security of the network. By using dPoW, Komodo developers can secure not only their own network, but also any third-party chain that joins their ecosystem in the future. In fact, dPoW can be implemented for any project that develops an independent blockchain using the UTXO model.


How does dPoW work?

Using Komodo as an example, the dPoW security mechanism was developed and implemented into the Zcash codebase, which provides zero-knowledge privacy and increases network security by using Bitcoin hashrate.

At ten minute intervals, the Komodo system takes a snapshot of its blockchain. The snapshot is then recorded into a block on the Bitcoin network in a process called notarization. Essentially, this process creates a backup of the entire Komodo system, which is stored on the Bitcoin blockchain.

Technically speaking, community-elected Komodo notary nodes write the block hash from each dPoW-protected blockchain to the Komodo ledger, executing an on-chain transaction. Using the OP_RETURN command, notary nodes store the hash of one block on the Komodo chain.

The reason notary nodes choose a hash block that is about ten minutes old is because the entire network has agreed that the block is valid. Each blockchain's network still comes to a consensus on each block. Notary nodes simply record the hash of the previously mined block

Once Bitcoin notarization occurs, Komodo notary nodes write the block data from the BTC chain back to any other secure chain. At this point, the network will not accept any reorganizations that attempt to change the notarized block (or any blocks that were created before the last notarized block).

dPoW is currently used with Bitcoin, but it could potentially be used as a tool to provide both the security and functionality of any other blockchain using the UTXO model.


PoW vs dPoW

One of the main goals of the Proof of Work (PoW) algorithm is to maintain network security, preventing cyber attacks and distributed denial of service (DDoS) attacks. In a few words, a PoW algorithm is a piece of data that is very expensive to produce but easy for others to verify, and which is also a critical element in the mining process.

Mining in PoW-based blockchains is very difficult. Miners must solve a complex cryptographic puzzle to be able to mine a new block. Such a process involves intensive computational work, which is very expensive in terms of hardware and electricity. The mining process not only protects the network from external attacks, but also verifies the legitimacy of transactions and generates new cryptocurrency units (as a reward for the miner who solves the puzzle).

Therefore, one of the reasons for the security of Proof of Work blockchains is the fact that the mining process requires a very large financial investment and depends on consensus in the network. However, it is important to note that the security of PoW is directly related to the amount of computing power (hashrate) allocated to them, meaning that small blockchain networks are less secure than larger ones.

Unlike PoW, dPoW is not used to reach consensus on new blocks and is thus not a consensus algorithm. Instead, it is a security mechanism that is implemented in addition to the normal PoW consensus rules. DPoW makes it impossible to reorganize blocks that have been notarized, meaning it makes blockchains much more secure and 51% resistant to attacks.

Essentially, dPoW “resets” the rules agreed upon by the blockchain every time a block is notarized. For example, most PoW chains use the “longest chain rule”. Thus, every time the blockchain network receives confirmation that block XXX, XX1 has been notarized, then according to the longest chain rule, the next block will begin with XXX, XX2. The network will not accept a chain that starts with block XXX, XX0 or earlier, even if it is the longest.


Conclusion

The Delayed Proof of Work security mechanism allows for regular backups, ensuring that in the event of a system failure or successful hacking, all data can be quickly restored. For the hack to successfully cause lasting damage, the attacker would also have to take down the Bitcoin network, destroying all snapshots that were archived on its blockchain.

For those who would like to learn more about Delegated Proof of Work, please visit the Komodo Blockchain Security Services page.