How to play
Blackjack basics, and what makes Cipher21 different.
Beat the dealer by getting your hand total as close to 21 as possible — without going over.
Cipher21 uses C21 chips — a confidential ERC-7984 token deployed alongside the game — instead of ETH for bets. Your chip balance is encrypted; only your wallet can decrypt it.
Hit Claim 1,000 C21 once per hour from the public faucet. Free, no signups.
Sign one tx to let the table pull chips when you bet — like an ERC-20 approval, but private.
Pick a stack (10 / 25 / 50 / 100 / 250 C21) and deal. You only need a tiny bit of Sepolia ETH for gas.
Face value (a seven is worth 7).
Worth 10.
Worth 1 or 11 — whichever is better for your hand.
You bet between 10 and 500 C21 chips. The contract pulls them via confidentialTransferFrom — encrypted on-chain.
You receive two cards. Only your wallet has the key to decrypt them.
The dealer gets two cards. One is visible; the other is an encrypted ciphertext.
Hit
Draw another card. Do this when your total is low and you need more to beat the house. Each hit is a separate on-chain operation.
Stand
Keep your current total and end your turn. The dealer then reveals their hole card and auto-plays according to house rules.
The house must hit until their total reaches 17. They stand on all 17s. If the dealer busts, any player hand still in play wins automatically.
Every card is generated on-chain using FHE randomness. Your hand stays encrypted to your wallet. The hole card is sealed to everyone until showdown. No peeking.