What is CPOC Consensus?
Conditioned Proof of Capacity is the method XHD uses to confirm blocks and assign mining rewards. It does not rely on raw computing power. Miners prepare hard drive space in advance, then use that plotted capacity to compete for blocks. During validation, the network reads stored plot data from disk and bases rewards on the network’s total plotted capacity.
How does CPOC mining work?
Mining starts with plotting. The miner fills the hard drive space with plot files before any block search starts. Each file contains nonces produced through SHA-256 hashing and tied to the miner’s account ID. More plotted space creates more nonces, which improves the odds of a winning result.
A Proof of Work miner calculates new hashes nonstop. A CPOC miner does the computation upfront. Once plot files exist, mining becomes a read operation against stored data instead of a live calculation.
What does “conditioned” mean in CPOC?
Standard Proof of Capacity pays block rewards on a fixed schedule. CPOC doesn’t. The protocol ties reward output to the network’s total plotted storage, recalculated over a 2016-block rolling window. The reward rate moves with how much capacity miners add or remove.
| Network capacity | Reward rate |
|---|---|
| Below 1,000 PB | 8,000 XHD per T |
| Past 1,000 PB | Adjusted per network capacity value, averaged across a 2016-block window |
What is the CPOC algorithm?
Each nonce inside a plot file contains 4,096 scoops. A scoop is a pair of Shabal-256 hashes. Miners generate this data once during plotting, and the files stay on disk after that.
The network produces a generation signature when a new block arrives, derived from the previous block. That signature determines which scoop number every miner reads. Miners read the scoop from every nonce in their plot files and hash it against the generation signature to get a deadline value.
The lowest deadline wins. The miner submits it, the network compares all submissions, and the shortest verifiable deadline determines who forges the block.
How do nodes validate blocks?
A node receives the miner’s deadline claim and checks the result on its own. The node checks the miner’s account ID, confirms the declared capacity, reads the correct scoop using the generation signature, and reproduces the deadline calculation. If the output matches and no shorter deadline exists, the node accepts the block.
Every honest node works from the same inputs and gets the same result. There is no voting round and no validator committee. Use the same generation signature and the same scoop data, and the formula returns the same deadline. Honest nodes converge on the same winner because the calculation has one result.
CPOC vs Proof of Work
Proof of Work
Proof of Work miners solve cryptographic puzzles nonstop and burn electricity through every cycle. A single Antminer S19 draws around 3,000 watts under load.
CPOC
An HDD reads plot data at 5 to 10 watts. A full multi-drive CPOC rig stays under 100 watts.
A 51% attack against a PoW chain requires rented or purchased hash power, sometimes for just hours. A CPOC attacker would need to acquire and plot more than half the network’s total disk capacity. Hard drives are physical and slow to fill. You can’t rent plotted storage the way you can rent hash power through a cloud provider.
Industrial PoW mining concentrates among operators with cheap electricity. A used 8TB drive costs ~$120-$180. A competitive ASIC costs several thousand dollars before power bills. CPOC has a lower entry cost, though the security budget rests on cheap commodity hardware rather than purpose-built machines.
CPOC vs Proof of Stake
Proof of Stake replaces miners with validators. Ethereum’s PoS system uses validators who lock ETH in a smart contract. They check new blocks and sometimes create them. If a validator acts dishonestly, they can lose part of their staked ETH.
CPOC doesn’t require staked coins. A miner proves storage access through plot files and block responses. The network ranks participants by deadline results. Coin holdings play no role in block production. PoS punishes dishonest behavior through slashing. CPOC makes attacks costly because the attacker needs real disk capacity.
CPOC and Proof of Space
CPOC overlaps with Proof of Space, though the labels are not interchangeable. Proof of Space uses reserved storage to prove a participant assigned disk capacity to the network. Chia, for example, combines Proof of Space with time proofs from timelords.
CPOC adds its own reward conditions on top of the storage proof. The capacity-linked reward formula and the 2016-block adjustment window are specific to this protocol. A CPOC blockchain follows its own algorithm and reward structure rather than copying every element of another Proof of Space design.
CPOC in XHD
A miner needs a wallet address before creating plot files. The wallet provides the account details used during plotting. The hard drive provides the capacity. Once plots are ready, the miner competes for block rewards on every new block.