Hash-Chain Auditor

What is a cryptographic hash chain?

Bustabit popularized the technique in the early crypto casino era. The idea: commit to millions of results before the first bet lands. The operator takes one random seed and runs it through SHA-256 over and over — sometimes as many as 10 million iterations — instead of rolling random numbers as each round happens.

Before any betting opens, the house publishes the final link in that chain (the “genesis” hash). SHA-256 only works one way, so nobody can reverse it to peek at upcoming seeds. But once rounds unfold in reverse order — last chain position played first — anyone can check that each revealed hash is the true SHA-256 parent of the one published for the prior round.

The math: Recursive SHA-256 hashing

Generation runs forward at setup; play and auditing run backward through the chain:

1. Forward generation (Casino setup)

Starting from a secret base seed ($S_0$), the operator applies the hash function $N$ times:

S₁ = SHA-256(S₀)
S₂ = SHA-256(S₁)
...
S_N = SHA-256(S_{N-1})  (This is the Genesis Hash, made public first)

2. Reverse verification (Player audit)

Play proceeds from round $N$ down to round 1. At any point $k$, take the current round’s hash ($S_k$) and confirm that hashing it reproduces the neighboring value ($S_{k+1}$):

SHA-256(S_k) = S_{k+1}

Step-by-step audit: Verifying a session log

Say you’ve finished a block of 100 crash rounds and want to check them. Most provably fair casinos export history logs as CSV files listing round numbers alongside their hashes:

1. Grab the CSV from your casino’s game history page.
2. Select the column holding the hex hashes.
3. Paste those hashes into the auditor box above.
4. Hit “Verify.” The tool hashes each row recursively and compares it against the next entry.
5. A fully green result means every round resolved correctly: none skipped, none inserted, none rewritten.

Frequently asked questions