A deliberately constrained search problem
Bitcoin Puzzles are public challenges in which funds were placed at addresses whose private keys were selected from deliberately limited numerical ranges. The range restriction turns an otherwise astronomically large private-key space into a smaller, well-defined search problem. “Smaller” does not mean small: later puzzles still contain so many candidates that exhaustive search remains a substantial computational task.
A search engine takes a start key, an end key and a public target. It derives the public information corresponding to each candidate and checks for a match. This is different from Bitcoin mining. Mining repeatedly varies block-header data to satisfy a network difficulty target; a puzzle search tests candidates inside a fixed private-key interval for one known target.
Why coordination matters
Two independent computers can both perform valid work and still waste collective effort if they search the same interval. That duplication becomes increasingly expensive as more participants join. OpenPuzzle treats a hexadecimal interval as a work unit, records which intervals are assigned or completed and prevents completed space from being issued again.
The coordinator does not make an interval more or less likely to contain the key. Its job is accounting: identify what has been searched, what is in progress and what can safely be assigned next. The cryptographic work remains on participants’ machines.
Coverage is not a prediction
If ten percent of a uniformly defined keyspace has been exhaustively searched, that proves something useful: those tested candidates did not contain the target key. It does not make the next individual candidate intrinsically “hotter”. Among the unsearched candidates, each remains one candidate in the remaining set.
This distinction is important when presenting live statistics. A coverage percentage is an audit metric. It should not be presented as a countdown, an expected discovery date or a guarantee. Search speed can estimate how quickly ranges are processed, but not where the unknown key sits inside the remaining interval.
What counts as useful evidence
A trustworthy distributed search needs more than a counter. It needs explicit boundaries, non-overlap rules, progress checkpoints, completion validation and clear treatment of cancelled or interrupted work. A partially searched range must not silently become “complete”. OpenPuzzle therefore separates completed, assigned, failed, cancelled and expired lifecycle states.