MINES PROVABLY FAIR VERIFIER
Every Mines board you ever played is frozen inside a hash. Give this page the revealed seed pair and the bet’s nonce and it rebuilds the 5×5 grid tile by tile, showing precisely which squares were rigged with bombs before your first click.
Bomb tiles are drawn from the float stream of HMAC-SHA256(server seed, "clientSeed:nonce:cursor"), one float per mine. Stake and Shuffle boards reproduce exactly here; BC.Game and some others order seeds differently — the scheme table has the details.
Draw Sequence
The whole tension of Mines is information asymmetry: the casino knows where the bombs sit and you are guessing. Provably fair keeps that asymmetry honest — the layout is a deterministic function of a seed pair committed before the round, so “the mine moved under my click” is a checkable claim, not a feeling. Rebuild the board here and see for yourself where the bombs actually were.
HOW MINE POSITIONS ARE CALCULATED
Mines uses a shrinking-pool (Fisher–Yates) shuffle so no two mines land on the same tile:
- Generate one float per mine from the HMAC stream (it advances the cursor automatically as bytes are consumed).
- Start with a pool of tiles [0..24]. For each mine,
idx = floor(float × remaining-pool-size), take that tile, and remove it from the pool.
To sanity-check the port: the vector pair some server seed / some client seed at nonce 1, played with 3 mines, buries the bombs under tiles 15, 21, 4 (counting 1–25 across the rows). Any mine count from 1 to 24 just extends the same draw — more floats, same stream, still reproducible.
BOARD COMBINATORICS: WHAT FAIR LOOKS LIKE
A 5×5 grid with n bombs has “25 choose n” possible layouts: 25 boards with one mine, 2,300 with three, 53,130 with five, and back down to 25 again with twenty-four (only the safe square varies). A fair generator must make each of those layouts equally likely, and the shrinking-pool draw achieves that: the first float picks among 25 tiles, the next among the remaining 24, and so on, exactly like dealing cards from a shuffled deck. It also pins down your real odds — with three mines, the first tile you open is safe 22 times in 25 (88%), and surviving two picks happens with probability 22/25 × 21/24 ≈ 77%. Payout curves are priced against those fractions, minus the house margin.
WHAT REBUILDING A BOARD SETTLES
The one accusation that haunts every Mines table is relocation — that the bomb teleported onto whichever tile you touched. A rebuilt board answers it conclusively: the tile list this page prints comes from data the casino committed to (as a hash) before the round existed, and your client seed was stirred in from your side. If the recomputed bombs sit where you died, the layout predated your clicks; if the revealed seed fails to match its pre-round hash, you hold cryptographic evidence of tampering. That is the entire dispute, resolved either way — though note a fair board still carries the game’s built-in margin, and the commitment scheme itself is worth understanding once.
Related Resources
Play Mines: Stake Mines
Strategy: Mines Strategy Guide
Boards you can rebuild anywhere: the provably-fair operator list