SHA-256
A cryptographic hash function that turns any input into a fixed 256-bit output; used to commit to server seeds.
SHA-256 is a hash function from the SHA-2 family standardized by NIST. It takes any input and produces a 256-bit (32-byte) output, usually written as 64 hexadecimal characters.
Properties that matter
- Deterministic: the same input always gives the same output.
- One-way: you cannot work backwards from the output to the input.
- Collision resistant: it is not feasible to find two inputs with the same output.
- Small changes to the input change the output completely.
How provably fair games use it
The casino publishes SHA-256(server seed) before you play. Because of the one-way property, you cannot learn the seed early. Because of collision resistance, the casino cannot later reveal a different seed that matches. SHA-256 is also the hash inside HMAC-SHA256, which generates the results.
Worked example
The SHA-256 of the text "abc" is ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad. Change one letter and the output is unrecognizable. You can check this yourself in any SHA-256 tool.