⏱️ Delayed Proof of Work dPoW
A second-layer security trick that periodically copies a small chain's recent block hashes onto a larger Proof-of-Work chain, so the little chain borrows the big one's strength to fight off 51% attacks. Built by the Komodo project — it is not a consensus algorithm by itself.
🏦 The simple version — a photocopy in a bank vault
Picture keeping your own ledger at home, then dropping a time-stamped photocopy into a giant bank's vault every few minutes. Anyone who wants to forge your records now has to fake the page at home and break into the vault to swap the copy. That is what dPoW does for a small blockchain: it tucks a snapshot of recent history into a much bigger, harder-to-touch chain. The small chain keeps running normally; the photocopy is just a backup that makes cheating absurdly hard.
🔍 How a block gets "notarized"
A group of community-elected notary nodes (around 64 of them) does the copying. They take a block hash that is about 10 minutes old (old enough that the whole network already agrees it is valid) and write it into the big chain using a small data command called OP_RETURN. That step is called notarization. Once a block is notarized, the network refuses any reorganization that would change that block or any block before it. In effect, the longest-chain rule gets re-set at the most recent notarized block.
🛡️ Why this stops a 51% attack
Small Proof-of-Work chains are fragile: their safety rises with hash rate, so a chain with little mining power is cheap to overpower. dPoW lets that small chain rent a giant chain's strength without merging into it. To rewrite notarized history, an attacker would have to:
- ⛏️ 51%-attack the small chain — already hard, but doable on a low-hashrate network on its own
- 🏔️ And rewrite the giant anchor chain at the same moment — redoing Bitcoin or Litecoin's work, which costs a fortune
- 💸 Pay for both at once — the combined bill is so high the attack stops making sense
📌 The small chain doesn't get faster or richer from dPoW — it only gets harder to rewrite. Speed and fees are still set by the chain's own rules.
🏔️ Which big chain does it lean on?
| Period | Anchor chain |
|---|---|
| Original design | Bitcoin — the chain with the most hash power |
| Around mid-2021 onward | Litecoin — Komodo switched the anchor at Notary Node Season 5 |
dPoW was designed by the Komodo project and can be bolted onto any independent UTXO-model blockchain. Older write-ups (including some that predate the 2021 switch) still describe the anchor as Bitcoin.
🚨 Things beginners should know
- 🧩 It's a layer, not a replacement — dPoW sits on top of normal consensus; it does not pick new blocks
- 👥 It leans on notary nodes — a fixed group of elected nodes does the copying, so it is not fully trustless like solo mining
- ⏳ Protection is for confirmed history — only blocks already notarized get the extra lock, not the very newest ones
- 💵 Fees on the anchor chain are real — writing to a big chain costs money, paid by the protected network
❓ FAQ
- Is dPoW its own consensus algorithm, like Proof of Work?
- No. dPoW does not decide which new blocks are valid — the chain's normal consensus (such as Proof of Work) still does that job. dPoW is an extra security layer added on top that anchors already-agreed history onto another chain.
- Which big chain does dPoW write to?
- dPoW originally anchored to Bitcoin. The Komodo project later switched the anchor to Litecoin around mid-2021 (Notary Node Season 5). Either way, the idea is the same: lean on a chain with far more hash power.
- Why can't an attacker just rewrite the history anyway?
- To change a notarized block, an attacker would have to 51%-attack the small chain and rewrite the much larger anchor chain at the same time. Attacking a giant chain like Bitcoin or Litecoin is wildly expensive, so the combined cost is practically out of reach.