Key Takeaways
Delayed Proof of Work (dPoW) is a secondary security mechanism introduced by the Komodo project that anchored block hashes to the Bitcoin blockchain to protect smaller Proof of Work networks.
dPoW is not a consensus algorithm; it works alongside ordinary PoW rules and helped make notarized blocks resistant to reorganization and 51% attacks.
Community-elected notary nodes periodically recorded block hashes from protected chains and wrote them onto Bitcoin using OP_RETURN transactions.
In January 2026, Komodo retired dPoW on its main chain in favor of Auto Checkpoints, while a parallel chain called Komodo Classic preserved the original dPoW design.
Introduction
Smaller proof-of-work blockchains often face a security problem: their limited hash power can leave them exposed to attackers with more computing resources. Delayed Proof of Work (dPoW) was one approach designed to address this imbalance. This article explains what dPoW is, how its notarization process worked, how it differs from ordinary Proof of Work, and what changed after Komodo retired the mechanism in 2026.
What Is Delayed Proof of Work?
Delayed Proof of Work (dPoW) is a security mechanism designed by the Komodo project. It is a modified version of the proof-of-work (PoW) consensus algorithm that uses the Bitcoin blockchain’s hashpower to enhance network security.
By using dPoW, Komodo developers could secure not only their own network but also any third-party chain that eventually joined the Komodo ecosystem. Any project that developed an independent blockchain using a UTXO model could also implement dPoW. The mechanism was intended to make protected chains far more resistant to 51% attacks, since an attacker would need to overpower not only the smaller chain but also the security anchored in Bitcoin.
The Zcash codebase also implemented dPoW, allowing zero-knowledge privacy while increasing network security by leveraging Bitcoin’s reputation and immutability.
How Does dPoW Work?
At intervals of roughly ten minutes, the Komodo system takes a snapshot of its own blockchain. Then, the snapshot is written into a block on the Bitcoin network in a process called notarization. This process creates a backup of the Komodo system state, which is saved within the Bitcoin blockchain, the network with the largest hash rate of any blockchain.
Technically speaking, Komodo’s community-elected notary nodes write a block hash from every dPoW-protected blockchain onto the Komodo ledger by executing a transaction on the Komodo chain. Using the OP_RETURN command, the notary nodes store a single block hash onto the Komodo chain.
The reason why the notary nodes select a block hash about ten minutes old is to ensure that the entire network agrees the block is valid. Each blockchain’s network needs consensus for each block. The notary nodes simply record a block hash from a previously mined block.
Then, the notary nodes write a block hash from the Komodo chain onto the Bitcoin ledger. This process is also completed by executing a BTC transaction and using OP_RETURN to write the data into a block on the Bitcoin chain.
Once this notarization to Bitcoin occurs, Komodo’s notary nodes write that block data from the BTC chain back onto the chain of every other protected chain. At this point, the network will not accept any re-organizations that attempt to change a notarized block, or any blocks that were created prior to the most recently notarized block.
dPoW effectively "re-sets" a blockchain’s consensus rules every time a block was notarized. Most PoW chains use the "longest chain rule." So each time a blockchain’s network receives confirmation that block 1,000,001 has been notarized, the longest chain rule effectively starts over at block 1,000,002. The network would not accept a chain that began at block 1,000,000 or prior, even if it was the longest one.
PoW vs. dPoW
One of the main goals of the Proof of Work algorithm is to maintain network security, deterring cyberattacks such as Distributed Denial-of-Service attacks (DDoS). In short, the PoW algorithm relies on a piece of data that is very costly to produce but easy for others to verify, and it is a crucial element of the mining process.
Mining within PoW-based blockchains is very demanding by design. Miners need to solve a complex cryptographic puzzle in order to be able to mine a new block. Such a process involves intense computational work, which is very costly in terms of 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 cryptocurrency units as a reward to the miner that solves the puzzle.
In contrast to PoW, dPoW is not used to achieve consensus on new blocks and is therefore not considered a consensus algorithm. Instead, it is a security mechanism implemented in addition to ordinary PoW consensus rules. dPoW makes it virtually impossible to reorganize blocks that were already notarized, so blockchains became more secure and resistant to 51% attacks.
What Happened to dPoW?
While dPoW is still used with Bitcoin as the anchor chain in some communities, its original flagship deployment changed significantly. In January 2026, the Komodo project retired dPoW on its main chain as part of the Draco Typhon upgrade (version 0.9.2).
The main KMD chain replaced notarization to Bitcoin with a new system called Auto Checkpoints, which periodically records internal checkpoints without requiring Bitcoin transactions.
At the same time, a parallel chain called Komodo Classic (KMDCL) was launched to preserve the original dPoW design for users and projects that preferred the notarization-based security model. Pirate Chain, one of the notable projects that relied on Komodo’s dPoW service, migrated its notarizations to Komodo Classic. This means the dPoW concept remains active, though its primary platform and ecosystem have shifted.
Frequently Asked Questions
Is dPoW a consensus algorithm?
No. dPoW is a secondary security mechanism implemented on top of ordinary Proof of Work consensus rules. It does not determine how new blocks are produced; it anchors finalized block data to a more secure chain to deter reorganizations.
What is notarization in dPoW?
Notarization is the process by which community-elected notary nodes write block hashes from a protected chain onto the Komodo ledger, and then onto the Bitcoin blockchain using OP_RETURN transactions. This effectively backs up the protected chain’s recent history on Bitcoin.
Why did dPoW anchor data to Bitcoin?
Bitcoin is widely considered the most secure blockchain because of its enormous hash rate and decentralized mining network. By anchoring notarized hashes to Bitcoin, smaller chains could borrow a level of security that would otherwise be impractical for them to achieve on their own.
Is dPoW still in use today?
Komodo retired dPoW on its main chain in January 2026 in favor of Auto Checkpoints. However, a parallel chain called Komodo Classic continues to support the original dPoW mechanism, and projects such as Pirate Chain migrated their notarization services to it.
Closing Thoughts
The delayed Proof of Work security mechanism allowed for frequent backups to ensure that, in the event of a system failure or successful hack, the data could be quickly recovered. For a hack to cause lasting damage, an attacker would have to compromise the Bitcoin network as well, destroying the snapshots that were backed up within the Bitcoin blockchain.
Even though Komodo has moved its main chain to Auto Checkpoints, dPoW remains an instructive example of how smaller networks can borrow the security of larger ones.