SHA-256
A cryptographic hash that maps any input to a fixed 256-bit digest; casinos use it to commit to server seeds.
SHA-256 belongs to the SHA-2 family of hash functions standardised by NIST. Whatever you feed it, it returns 256 bits (32 bytes), normally displayed as 64 hex characters.
Four properties that matter for fairness
- Deterministic: identical input always yields identical output.
- One-way: the output gives no route back to the input.
- Collision resistant: finding two inputs that hash to the same value is not feasible.
- Avalanche effect: a tiny edit to the input produces a completely different output.
Its two jobs in provably fair games
First, the casino publishes SHA-256 of the server seed before you bet. The one-way property keeps the seed secret until then, and collision resistance stops the casino revealing some other seed that fits. Second, SHA-256 is the hash running inside HMAC-SHA256, the function that produces the results.
Try it yourself
Hash the text "abc" and you get ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad. Alter a single letter and the digest looks nothing alike. Any SHA-256 tool will confirm it.