CKB Testnet Mining Competition Round 2: Earn 4,000,000 CKB here!

To reward our community for participating in the construction of Nervos CKB, the Nervos Foundation is sponsoring Round 2 of the CKB testnet mining competition! Anyone can participate in the testnet mining, and potentially win a total of 4 million mainnet CKB tokens.

After the first round of our mining competition, we released RFC (Request for Comment) on our forum to ready us for the second round. We gathered comments from our community members and adapted the rules as follows:

Time: July 13 6:00 AM (UTC) - July 27 6:00 AM (UTC)

Reward distribution:

The community pool rewards (2,000,000 CKB)

All addresses that have mined at least 4,000 CKB testnet token will share this reward pool and receive CKB rewards in proportion with the blocks produced by each address.

The lucky block rewards (2,000,000 CKB in total, 80 winners)

On the current Nervos CKB testnet, there is one difficulty adjustment epoch in about every four hours. We expect there will be 84 epochs in total during the two weeks’ mining competition based on what we saw in the mining competition phase 1. From Epoch 1 to Epoch 80, any address that mined the first block aka lucky block in each epoch will be rewarded 25,000 CKB. Note the genesis Epoch (Epoch 0) is not included.

Competition Process

7.13 5:00 UTC, Release CKB testnet v0.16.0 in Github ( ONLY using this testnet version can participate in mining competition.

7.13 6:00 UTC Competition begin. Blockchain explorer will be ready in two hours.

7.27 6:00 UTC, competition is over. We will release the result within one day in this website.

How to participate

To start mining on CKB testnet, simply follow the steps outlined in the official guide or community-created tutorials on Nervos Talk. A CKB blockchain explorer is also available to look up your mining rewards.

CKB-Mine-Lord website created by our community member to show the rank of all the addresses, you can check it to get your real-time rank, here is the code of this website for your reference.

Upon the completion of the competition, we will calculate block rewards mined by each address. The accumulated block reward of each address during the competition will form a basis for CKB mainnet token rewards (testnet tokens gained by transactions will NOT be counted as block rewards).

Rewards will be distributed directly to respective addresses on CKB mainnet. Please exercise caution when managing your private key as it will be your sole means of claiming your CKB token rewards.


  • How are the block rewards in CKB different from those in Bitcoin?
    • For Bitcoin, the block rewards are fixed in each block you mine; For CKB, the total block rewards are fixed in each difficulty adjustment epoch. CKB consensus adjusts difficulty to adjust block time, when difficulty increases, there will be less blocks mined during one epoch, but block rewards in each block mined will be increased.
  • What is difficulty adjustment epoch in CKB?
    • On the current Nervos CKB testnet, we target difficulty adjustments at every four hours (In Bitcoin, the difficulty adjust happens every 2016 blocks, while the block interval is 10 mins). For more details please refer to our Consensus RFC.
  • Why do the community pool rewards only apply to addresses that mined at least 4,000 CKB testnet token ?
    • The native token CKByte represents state storage space on the Common Knowledge Base blockchain. A cell is the basic data structure in the blockchain, and you can put any arbitrary data in a cell. It requires 60 CKBytes to create a cell.
    • During mining competition phase ONE, 105,000,000 CKB testnet token were mined, and we expect the same amount of testnet token will be mined in phase 2. Given the community pool rewards of 2000,000 CKBytes, it requires you to have at lease 3,150 CKB testnet token mined to be able to receive the 60 CKBytes rewards. We add some buffer and require at least 4,000 CKB testnet token to receive rewards.
  • When should I increase my hashrate in order to get the lucky block reward?
    • Increase the hashrate when getting closer to the start number of next epoch. You can calculate the start number of next epoch based on the current epoch start number (block height) and the length of each epoch in CKB explorer.
  • After mining a block, how long does it take to receive the block rewards?
    • The block rewards from Block N will be received in Block “N + 11” (about 3 minutes) via Cell Base Transaction.
  • How to know the value of token?
    • There’s 33.6 billion CKBytes mainnet token in genesis block ,more info will be disclosed later.

Things to Note

  • This is the second round of competition in a series. It is possible that any future rounds will have different rules and rewards.
  • CKB tokens rewards will have a lock-up period of 6 months. The specific block height at which these reward tokens get unlocked will be announced prior to mainnet release.
  • Addresses for the same private key might be different on testnet and on mainnet due to difference in algorithm. Participants only need to hold on to their private key to be able to claim rewards.
  • Participation in this event means that you have read and understood the competition terms.
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