Documentation
Mining Process
Introduction
OP_NET mining is fundamentally different from Bitcoin mining. Instead of competing to create new blocks, OP_NET miners compete to checkpoint epochs; groups of five Bitcoin blocks that have already been mined. This section explains exactly how OP_NET mining works, what miners compute, and why this design creates fork-impossible consensus.
OP_NET miners do not create blocks or determine transaction inclusion. They function as witnesses competing to checkpoint deterministic execution that has already occurred. Mining provides proof-of-work security for state finalization rather than transaction ordering.
End of Epoch
When an epoch ends, it produces a checksum root. A checksum root is a cryptographic fingerprint of the entire epoch's final state. This checksum root becomes the challenge that miners must solve. The challenge isn't a puzzle like "find a hash with N leading zeros." Instead, it's "find the best SHA-1 near-collision with this specific checksum root."
Checksum Root
The checksum root is a SHA-256 hash representing every balance, every contract's storage, every single bit of data in the epoch's final state. If anything differs by even a single bit, the checksum root completely changes.
Deterministic Generation
Every node independently calculates the same checksum root by executing all transactions in the epoch deterministically. No voting or coordination is needed.
Immutable Target
Once an epoch ends, its checksum root is fixed. Miners cannot change it, manipulate it, or choose a different one. The challenge is set in stone.
Public Availability
The checksum root is publicly available to all nodes and miners immediately when the epoch ends. No special access or permissions are required.
SHA-1 Near-Collision Mining
OP_NET uses SHA-1 near-collision mining rather than Bitcoin's SHA-256 mining while serving a similar proof-of-work purpose. This choice is intentional: SHA-1 provides computational feasibility with sufficient security for the use case.
SHA-1 Design Rationale
Collision Search Speed
SHA-1 is faster to compute than SHA-256, allowing miners to try more attempts in the same time period. This creates a competitive mining market without requiring excessive hardware investment.
Near-Collision Difficulty
Finding SHA-1 near-collisions (high bit-match counts) is computationally expensive. Achieving 80+ matching bits requires significant proof-of-work, providing security against manipulation.
Not About Full Collisions
OP_NET doesn't require full SHA-1 collisions (which are theoretically breakable). It requires near-collisions with a specific target, which remains computationally hard.
Deterministic Comparison
SHA-1 hashes provide deterministic comparison: given two solutions, counting matching bits produces the same result on every node, enabling fork-impossible winner selection.
The Attestation Requirement
Every epoch solution must include an attestation to the state from 4 epochs ago. This is the mechanism that makes OP_NET forks mathematically impossible.
By requiring attestations to state from four epochs ago, approximately 21 blocks deep, OP_NET ensures all nodes reference identical historical data. This eliminates ambiguity since the system references deeply-buried history that all participants must agree on rather than recent blocks.
Mining Economics
OP_NET mining creates a unique economic model with future reward payouts.
Computational Cost
Miners invest in computing hardware, electricity, and Bitcoin transaction fees to submit solutions with no guarantee of winning.
Future Rewards
Winners receive gas fees from 3 epochs in the future (~150 minutes delay), preventing manipulation and incentivizing long-term network health.
Pure Market
High network usage creates high gas fees and rewards; low usage creates low rewards. The market naturally adjusts mining participation based on profitability.