provably fair calculator

Want to verify a game result yourself instead of trusting a black box? This provably fair calculator lets you independently reproduce outcomes using a server seed, client seed, and nonce. It supports two common output styles: a dice roll (0.00 to 99.99) and a crash-style multiplier.

What “provably fair” means

A provably fair system usually follows a commit-reveal process. Before gameplay, the platform commits to a secret server seed by publishing its hash. Later, it reveals the original server seed. Because hash functions are one-way, the platform cannot easily change the server seed after the fact without breaking the earlier hash commitment.

You can then combine that server seed with your client seed and a nonce (round counter) to regenerate the same cryptographic output. If your reconstructed output matches the published game result, the round is verifiable.

How this calculator computes results

1) Build the message

For each round, the calculator creates a message string in this format:

clientSeed:nonce

2) Generate HMAC-SHA256

The message is hashed with HMAC-SHA256 using serverSeed as the key. This produces a 64-character hexadecimal digest.

3) Convert the hash to a game output

• Dice mode: Uses the first 13 hex chars (52 bits), maps to a uniform value from 0 to under 100, then truncates to two decimals.
• Crash mode: Uses the first 13 hex chars in a common crash multiplier transformation, shown as x.

How to use the tool correctly

• Enter the revealed server seed from the platform.
• Paste the server seed hash (optional but recommended) to verify commitment integrity.
• Enter your client seed.
• Set the starting nonce (the exact round index matters).
• Set number of rounds and click Calculate Results.

Common mistakes that cause mismatches

• Using the wrong nonce (off-by-one errors are very common).
• Accidentally including extra spaces in seeds.
• Comparing to a platform that uses a different message format (for example nonce:clientSeed instead of clientSeed:nonce).
• Using different output formulas than the original game logic.

Interpretation and trust model

A provably fair system can prove consistency of outcome generation, but it does not prove favorable odds or responsible design. Verification shows that a published rule was followed for a given round; it does not remove risk, variance, or house edge.

Quick checklist for independent verification

• Confirm SHA-256(serverSeed) equals the pre-committed server hash.
• Recreate HMAC with the same message format and nonce.
• Apply the same conversion formula used by the game.
• Compare your output to the recorded round result.

This calculator is intended for transparent, educational verification workflows. If a platform documents a different formula, adapt the conversion step accordingly.