A provably fair verification tool is suitable for users who can enter a game’s server seed and client seed to verify shuffle fairness; this appeals to crypto‑casino players and builds authority in blockchain gaming.

Provably Fair Verification Free Tool

Provably Fair Verification (HMAC-SHA256):

Verify Seeds, Reproduce Results, Prove Integrity

This page lets players, reviewers, and compliance teams verify provably fair games by checking the server seed commit (SHA-256), combining it with the client seed and nonce, and recomputing the outcome. No black boxes, no vibes—just deterministic HMAC-SHA256 and reproducible RNG.

What “provably fair” actually means

• Server seed commit (pre-game): the operator publishes SHA-256 hash of a secret server seed.
• Play: outcome is derived from HMAC-SHA256(server_seed, pattern(client_seed, nonce)).
• Reveal (post-game): the operator discloses the server seed; the commit must match.
• Verification: anyone can reproduce results with the same inputs. If it doesn’t match, it’s not fair.

Tags: provably fair casino, HMAC-SHA256 commit, server seed reveal, client seed, nonce, deterministic RNG, fairness verification tool.

Supported games & output ranges

Game	Source of randomness	Output range	Notes
Dice	Unbiased ints from HMAC stream	0–99 or 0–99.99	Precision selectable.
Roulette (EU)	Unbiased int mod 37	0–36	Single zero wheel.
Roulette (US)	Unbiased int mod 38	0–36 + 00	37 maps to “00”.
Crash (generic)	First 52 bits → r; mult=(1−edge)/(1−r)	≥ 1.00×	Edge and decimals configurable.
Card Shuffle	Deterministic Fisher–Yates	52-card permutation	Output top N cards.

How to verify (step-by-step)

1. Paste server seed (revealed) and the commit hash supplied before play.
2. Paste client seed and starting nonce; choose round count.
3. Pick the game. Adjust precision/edge if relevant.
4. Click Verify & Generate.
5. Compare the tool’s results to the operator’s game log. Commit must match and round outputs must align exactly.

Why the commit matters

Without a pre-committed hash, the operator could swap server seeds post-facto to fit favorable outcomes. A SHA-256 commit → reveal guarantees precommitment: the revealed seed either hashes to the original commit (honest) or it doesn’t (caught).

Security model: what’s guaranteed (and what isn’t)

• Guaranteed: No post-game tampering if the commit matches and outcomes recompute bit-for-bit.
• Not guaranteed: payout policies, RTP, rounding rules, third-party integrations, or off-chain salts an operator didn’t publish. Always verify the exact message pattern (e.g., {client}:{nonce}) and any salts the operator documents.

Common pitfalls

• Wrong message pattern (token order, separators).
• Using the wrong nonce (0-based vs 1-based).
• Comparing EU vs US roulette incorrectly (00 handling).
• Crash decimals/edge mismatched with house rules.
• Hex vs UTF-8 confusion for seeds (operators should use text seeds, not hex blobs—this tool expects UTF-8 strings).

Compliance & trust benefits

• Audit trail: Reproduce historical rounds for KYC/RG investigations.
• Dispute resolution: Cryptographic proof beats screenshots.
• Link-worthy resource: Affiliates and compliance blogs naturally cite provably fair verification pages with tools.

Troubleshooting checklist

• Does SHA256(server_seed) equal the published commit?
• Is your client seed identical (case/whitespace)?
• Is the nonce the same as in the game log?
• Does the message pattern match the operator’s spec?
• For batch rounds, do results align round-by-round?

FAQ (for rich snippets)

What is a provably fair commit hash?
A SHA-256 hash of the server seed is published before play. It proves the seed existed and couldn’t be changed later without breaking the hash.

Which hash/HMAC does this tool use?
SHA-256 for commits and HMAC-SHA256 (server seed as key) for per-round randomness—an industry-standard approach.

Can I verify crash multipliers?
Yes. The tool derives r from the first 52 bits of HMAC output and computes mult = (1 − edge) / (1 − r). Configure house edge and decimals to match the operator.

What if an operator uses a different format?
Use “Advanced” to set the message pattern (e.g., {client}|{nonce}) and include any extra salts the operator documents.

Does this prove RTP?
No. It proves result integrity, not payout math. RTP is statistical and policy-dependent.