Winner Selection
EverDraw uses a commit-reveal mechanism powered by Monad block hashes to select winners. The process is fully on-chain, verifiable, and manipulation-resistant.
How it works
Step 1 — Commit
When the sales window closes, the keeper calls the commit function. The contract records a targetBlockNumber — a future block a fixed number of blocks ahead (currently 10 blocks, approximately 10–20 seconds on Monad).
The target block number is locked on-chain and cannot be changed. This is the commitment.
Step 2 — Draw
Once the target block is mined, anyone can call the draw function. The contract reads blockhash(targetBlockNumber) — the hash of the committed block — and uses it as the source of randomness.
The winning ticket is calculated as:
winningTicket = uint256(blockhash(targetBlockNumber)) % totalTicketsTicket ranges are mapped to buyer addresses sequentially. If you bought tickets 50–99 out of 200 total and ticket 73 is drawn, you win.
Step 3 — Verification
The winning ticket, the winner’s address, and the block hash used are all recorded on-chain and permanently verifiable. Any participant can independently verify the draw outcome by reading the contract state.
Why this design
It’s manipulation-resistant. No one knows what the block hash will be at the time of commitment. A block producer would need to control the exact target block and sacrifice the block reward to manipulate the outcome — economically irrational for any realistic prize pool size.
It’s transparent. The randomness source, the winning calculation, and the result are all public and verifiable on-chain. There is no black box.
It’s cheap. No oracle fees. No VRF subscription costs passed on to users. The block hash is native to Monad’s infrastructure.
Probability is strictly proportional
Your probability of winning = your tickets / total tickets in the round.
There are no bonus multipliers, no premium tiers, and no house edge. 1 ticket out of 100 total = 1% chance. 50 tickets out of 100 = 50% chance. The system is linear and fair by construction.