Blockchain 101: Understand PoC in One Article

8 min readSep 12, 2019


As early as 2014, the PoC consensus mechanism was released to the public. Until 2019, PoC began to receive attention from some miners in this space. What are the highlights of this consensus mechanism? How did it return to the spotlight of cryptocurrency after being forgotten? What are the PoC related projects? How will it develop in the future? In this article for Blockchain 101, let’s explore the PoC consensus.

1. What is PoC?

PoC (Proof of Capacity) is a consensus algorithm launched by Burst in 2014 that allows mining equipments to take advantage of the idle space of a local computer hard drive to participate in mining.

PoC puts a large number of hash calculations into the initialization phase, that is, the result of the hash calculation is written on the hard disk in advance through “mapping”. The bigger the miner’s hard drive, the higher chance there is to “retrieve a positive solution” (commonly known as disk scanning) before the deadline and get a block reward. In the consensus implementation phase, the need to use a large number of hash calculations in the PoW algorithm is reduced by scanning, so that in PoC mining, only a small amount of hash calculations are used in the execution phase. Compared with the PoW mechanism, PoC truly has the absolute advantage of energy saving and low threshold.

2. Why can PoC return to the stage of cryptocurrency in 2019?

In August 2018, the emergence of BHD completely led to the development of PoC. It combined some popular POS mechanisms and upgraded the consensus algorithm based on Burst:

1). Change the reduction of the block reward from 5% month by month to half every four years, and the block time is 5 minutes, and the block reward is 15BHD/block;

2). Add some rules for conditional mining and unconditional mining, equivalent to a derivative version of PoC.

In short, the concept of pledge is introduced — in the first month of mining, the miners can participate in mining with no requirements, and after that, every 1T of hard disk capacity miners need to pledge 3 BHD two they can get 95% of mining income. (The remaining 5% is reserved for the foundation to expand). This is called Conditional Mining. If miners don’t pledge BHD, they can only obtain 30%, and this is defined as Unconditional Mining.

The founding team of BHD came from China. It was led by Fang Xuchu, the founder of Aisi Community, Alex (Yang Jiaxue) and “Fatty” He Jialun, three of them together formed the vertical ecosystem of BHD. Under their vigorous promotion, BHD has received a lot of attention from the insiders. The PoC has also risen with flow and is gradually known by more people in this space.

3. PoC projects


Launched in 2014, Burst is positioned to become a high-speed payment platform that connects individuals, companies and financial institutions.

Like Bitcoin, the founder of Burstcoin is mysterious. On August 10, 2014, the developer nicknamed “Burstcoin” released Burstcoin to the public on The true identity of the founder is still a big mystery in cryptocurrency. For this reason, Burstcoin did not raise funds or provide premining, and the genesis block was created the next day.

Burst, also known as Burst Coin, is the first project to use the PoC consensus mechanism, featuring energy saving and hard disk mining. The new white paper, Dymaxion, was released at the end of 2017. Burst hopes to incorporate the proven protocols and ideas of other cryptocurrencies through the Dymaxion program, integrating IOTA’s DAG technology, Bitcoin’s lightning network technology and Monero’s anonymous technology to achieve a low-power, A highly scalable, anonymized currency payment system.

Burst has a maximum supply of 2.16 billion, with 2.06 billion mined, which exceeds 95% of the total volume. For miners, the bonus period has passed. In general, Burst as the first PoC project has great developmental implications for the entire PoC space.

2) BHD

BHD was established in August 2018. It creatively uses CPoC mechanism (Conditional Capacity Proof, a derivative version of PoC) , targeting at developing into a pricing financial system that changes the way cryptocurrency is produced.

BHD, with the full name BitcoinHD, is a digital cryptocurrency that is closely related to computer hardware and hard drive. The total supply is 21 million, 85% of which are supplied to miners. The initial TPS is 70 transactions/second, and the initial block size is 8M.

3) Lambda

Lambda was established in May 2018, which innovatively uses PoST mechanism (Time and Space Proof, upgraded PoC) a decentralized database system.

Lambda provides data storing capabilities to decentralized applications (DAPPs) and other public chains through logical decoupling and separate implementation on Lambda Chain (Consensus) and Lambda DB (Storage). In addition, Lambda Chain provides high performance through Sharding technology to support decentralized database services.

The Lambda storage section employs time and space to prove PoST. PoST originated from IPFS. It is essentially an upgraded version of PoC. The computing power is almost equal to the size of the data stored on the hard disk. However, it adds the concept of storage to the PoC. For PoST miners, in addition to the hard disk, they have to save the data of format to form an effective computing power.

The Lambda system has storing miners (providing storage space), verifying miners (guaranteeing data integrity) and retrieving miners (providing bandwidth). In the system, node-retrieving miners can obtain LAMB through mining, and to be a storing or retrieving miner requires LAMB to be pledged.

4) Spock

Spock was founded in 2019 and is positioned as a decentralized project release platform that adopts the PoC consensus mechanism.

Spock, somewhat similar to Ethereum, used the projects built on the PoC consensus mechanism, to encourage hard-drive miners, while adding the features of smart contract. In the future it will improve the features of smart contract and support the issuance of PoC tokens.

Spock borrowed from BHD’s “pledge & mine” system. Miners need pledge tokens to be qualified for mining. The difference is that the amount of pledged tokens that Spock takes is dynamically increasing or decreasing with the change of computing power. The advantages are:

a. avoid the high cost of new miners entering the market after the price of the currency has risen too high;

b. avoid the sudden entry of large computing power to hurt the interests of small miners.

The pledge system that Spock puts on can turn the token price and pledged computing power into a positive cycle, which will promote the development of the project ecosystem and form a positive cycle of ecosystem and the secondary.

Spock’s largest supply is 4.2 billion, with 8% premined and 30 million already mined. The overall still remains profitable to miners, the price of the token has not been significantly increased.

4. The overall comparisons between PoW, PoS and PoC

5. Prospects of PoC

It has only been five years since the birth of PoC and PoC is a consensus mechanism that is marginalized on the whole market, so there are only a handful of related projects on market. It remains to be seen whether PoC can become a consensus mechanism for the blockchain industry and even the entire society.

Updated PoC combines the advantages of PoW and PoS, and has a share on the market for its characteristics of being environmentally friendly, energy-saving and low-threshold. With the increasing popularity since the launch of IPFS and the disappearance of the old altcoin projects, PoC projects may receive another wave of attention. Compared with the small coins in the past, there should be a good increase on the market. To completely become the leader of the market recovery, it depends on whether it can withstand the test of time and gain market recognition.

CoinEx is committed to creating a safe, stable and efficient digital currency trading platform. We are optimistic about the future development of the PoC and willing to cooperate with the excellent projects in the PoC space to push its development. We welcome PoC project teams to contact us.

Further explanations of the PoC mechanism:

1) Hard Drive Mapping

How it works: A large number of Nonce is generated by the ShaBal hashing algorithm, written into the hard drive in the Plot format, and the work of the PoW is advanced to the initialization phase.

2) Mining (looking for the smallest deadline)

How it works: it generates a hash value from the Generation Signature of the previous block and the current block height, and then it performs a modulo operation on 4096, using the result to get the scoop data corresponding to the nonce, and then get the target value through hash calculation with the scoop data and the generation signature. The deadline value will be equal to the first 8 bytes of the target value divided by base target.

3) Network Synchronization

After the deadline information is obtained, the system will start counting down. If a valid block that is broadcast by other miners is received during the deadline, the packaging will be discarded. Otherwise, the wallet will package the current information into the block and broadcast it.

Terms Explanations:

  • Shabal Hashing Algorithm

Shabal is the main cryptographic hash function used by the PoC projects. Shabal is not a high efficient cryptographic hash function, but since hash calculations occur primarily during the drawing phase, the verification required for the operation is sufficient.

  • Plot Files
    When mining, the mining program reads pre-computed hash values from the hard drive and stores them. The files stored on the hard drive are Plot files.
  • Nonce
    Plot files contain some Nonces. A Nonce contains 8192 hashes and has a size of 256K bytes. Each Nonce is 8-byte.
  • Scoop
    Each Nounce contains 8192 hashes that are put into 4096 Scoops, and 2 hashes are placed in each Scoop.
  • Account ID
    This file is associated with the miner’s digital account ID when creating a Plot file. This ID is used to create a random number. Different miners will create different Nounces, although they may use the same nonce number.
  • Generation Signature
    Generation signature is generated based on the generation signature and miner ID of the previous block. This value is also included a block.