ExactOdds

Fair outcomes you can prove. Rules you can prove. Both, or neither.

ExactOdds is a protocol for provably-fair gaming with two halves: commit-reveal seeds (the outcome was fixed before your bet) and the exactness law (the game program produces byte-identical output on every target seat — Python, JavaScript, TypeScript, C, C++ — or the program is refused). Today's "provably fair" proves only the outcome. ExactOdds proves the rules too: the program an auditor gates is the only program that can pass, so a house can't run different rules in production than the ones it showed the auditor.

What's here

• games/ — the three reference games: provably-fair-dice.cuni, provably-fair-coin-flip.cuni, and provably-fair-roulette.cuni. Short, readable, deterministic: seeds in, result out.
• gate/ — the exactness gate runner (run-gate.sh), golden fixtures (fixtures/), and the per-seat gate report (GATE_REPORT.md).
• receipts/ — source-hash receipts from the verified 2026-09-26 runs.
• paper/ — PAPER.md (the full protocol paper), PAPER.pdf, and OPERATOR_ONEPAGER.md (one page for casino operators).

Verify a game in 5 steps (players)

You need the game's source, a SHA-256 tool, and any one of: Python 3, node, or gcc.

1. Get the source. games/provably-fair-coin-flip.cuni in this repo, or the copy your house publishes.
2. Hash it. sha256sum games/provably-fair-coin-flip.cuni must equal the source_hash in receipts/provably-fair-coin-flip.receipt.json. If not, that's a different game — stop.
3. Check the revealed seed. After your round the house reveals its server_seed. echo -n "$server_seed" | sha256sum must match the commitment published before you bet.
4. Re-run the round. Plug the revealed server seed, your client seed, and the round number into the program's flip function — any seat works; the gate guarantees they all agree. The output must match the result the house reported for your round.
5. Check the receipt. receipts/ holds the gated verdict. Auditors can re-run ./gate/run-gate.sh to reproduce the PASS.

Run the gate (auditors, operators)

./gate/run-gate.sh

This needs the ExactOdds reference compiler. Point it at your build:

PROVABLY_COMPILER=/path/to/cuni ./gate/run-gate.sh

It defaults to ../cuni-langs/target/debug/cuni (the lab tree), then ~/workspace/cuni-langs/target/debug/cuni, then cuni on PATH. For each game it emits all five native seats, runs them, demands byte-identical stdout, writes a fresh source-hash receipt into receipts/, and checks the output against the golden fixtures. Exit 0 means every game passed and no fixture drifted.

Reference

• Full protocol: paper/PAPER.md (also paper/PAPER.pdf)
• Operator summary: paper/OPERATOR_ONEPAGER.md
• Seat-by-seat evidence: gate/GATE_REPORT.md

License

Dual-licensed: AGPL-3.0 (LICENSE.AGPL-3.0) or the Slid Phi Labs Commercial License (LICENSE.COMMERCIAL). See LICENSE and NOTICE.

Copyright (c) 2026 Slid Phi Labs / Corey Tasz.

What this is not

Not a casino, not a gaming license, no custody of funds, not a randomness source. See §5 of the paper.