dPoW

Delayed proof of work (dPoW) is a security layer used by some blockchain projects to enhance the immutability of their chains by anchoring block data to a more secure network, typically Bitcoin, through a network of notarization operators. It is not a primary consensus mechanism for the main chain, but a supplementary mechanism designed to deter attacks that attempt to rewrite history on the target chain.

In a dPoW system, the main chain produces blocks using its own consensus method (commonly proof of work). At regular intervals, a set of notaries observes recent blocks and generates a notarization that commits the block headers to the Bitcoin blockchain. This notarization is often implemented with cryptographic signatures from multiple notaries, forming a threshold or multi-signature approval. Once the headers are embedded in Bitcoin, altering the notarized history would require tampering with Bitcoin itself, which is computationally expensive and practically unlikely.

The Notary Network provides cross-chain security by creating a time-stamped, tamper-evident record of a target chain’s progress on Bitcoin. This creates a “delayed” but robust finality mechanism: the longer the time since notarization, the harder it becomes to reverse the associated blocks on the target chain.

Commonly associated with the Komodo Platform, dPoW is used to protect Komodo’s own blockchain and other projects that adopt the scheme, and it can support cross-chain interoperability features. Limitations include potential centralization of notary operators, reliance on the security of the Bitcoin network, and added complexity compared to conventional on-chain security.