SHA-256
A hash function that turns any input into a fixed 256-bit fingerprint. Casinos use it to lock in their server seed.
SHA-256 is part of the SHA-2 family of hash functions, standardised by NIST. Feed it anything, and it gives back 256 bits (32 bytes), usually shown as 64 hex characters.
What makes it useful
- Same input in, same output out, every time.
- One-way: you can't go from the output back to the input.
- Collision resistant: finding two inputs with the same output just isn't doable.
- Change one tiny thing in the input and the output looks completely different.
Where you'll see it
The casino shows you SHA-256(server seed) before you play. Since it only goes one way, you can't figure out the seed early. Since collisions aren't doable, the casino can't later reveal some other seed that matches. SHA-256 is also the hash running inside HMAC-SHA256, which makes your results.
Try it yourself
Hash the word "abc" and you get ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad. Swap one letter and you get something totally unrecognisable. Any free SHA-256 tool online will show you.