How Results Are Generated

This article is for players who want the technical details. It explains how we turn your seeds into random numbers.

Step 1: Create random bytes

We use HMAC-SHA256. The server seed is the key. The message is your client seed, the nonce and a cursor, joined with colons:

HMAC_SHA256(key = serverSeed, message = clientSeed + ":" + nonce + ":" + cursor)

Each HMAC gives 32 bytes. The cursor starts at 0. If a game needs more than 32 bytes, we run the HMAC again with the cursor set to 1, then 2, and so on. We join the outputs in order.

Step 2: Turn bytes into numbers between 0 and 1

We split the bytes into groups of 4. Each group becomes one number, called a float, between 0 (included) and 1 (not included). So each HMAC gives 8 floats.

For a group of 4 bytes (b1, b2, b3, b4), the float is:

float = b1/256 + b2/256² + b3/256³ + b4/256⁴

Example

Say the first 4 bytes are 163, 244, 224 and 172.

• 163 / 256 = 0.636719

• 244 / 65,536 = 0.003723

• 224 / 16,777,216 = 0.000013

• 172 / 4,294,967,296 = 0.00000004

Adding them up gives a float of about 0.640455.

Step 3: Turn floats into a game result

Each game uses its floats in its own way. For example, Dice multiplies the float by 10,001, rounds down, and divides by 100. A float of 0.640455 gives a roll of 64.05.

See Game results for how every game uses its floats.