Getting Challenges

How Miners Obtain Challenges

Miners obtain challenges simply by running an OP_NET node. When an epoch ends, the node automatically:

1. Processes all transactions from the epoch's five Bitcoin blocks.
2. Executes smart contracts deterministically.
3. Generates the final state root.
4. Calculates the checksum root from this state.
5. Makes the challenge available to mining software.

Challenge Timing

Understanding when challenges become available and when solutions must be submitted is critical for miners.

The following provides a step-by-step explanation of each timeline element.
Values in angle brackets are examples for Block 569 and Epoch 113.

• Block N<569> (Epoch X<113> Ends):
  • All transactions from blocks N-4<565> to N<569> are finalized.
  • Nodes generate checksum root from final state.
  • Challenge becomes available immediately.
  • Mining competition begins.
• Blocks N<569> to N+4<574> (Epoch X+1<114> Submission Window):
  • Miners submit solutions via Bitcoin transactions.
  • Each solution includes SHA-1 collision proof.
  • Must attest to state from Epoch X-4<109> (blocks N-24<545> to N-20<549>).
  • No submissions accepted after block N+5<574>.
• Block N+6<575> (Winner Determined):
  • All nodes evaluate submissions from blocks N+1<570> to N+4<574>.
  • Highest SHA-1 collision quality wins.
  • Winner receives fees from Epoch X+3<116> (future epoch).