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Private Raffle

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How It Works

1. Authority creates a raffle with a ticket price
2. Players buy tickets with encrypted guesses (1-100)
3. Authority draws by setting an encrypted winning number
4. Players check if their guess matches (encrypted comparison)
5. Winners claim their prize through on-chain verification

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Privacy Guarantees

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Key Features

• Encrypted Guesses: Players submit encrypted numbers, hidden from everyone
• Encrypted Drawing: The winning number is never revealed on-chain
• Private Results: Only ticket owners can see if they won
• On-chain Verification: Winners prove their prize amount with Ed25519 signatures
• Trustless Payout: Prize transfers are verified and executed on-chain

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Quick Example

// Player buys ticket with encrypted guess
const myGuess = 42;
const encryptedGuess = await encryptValue(BigInt(myGuess));

await program.methods
  .buyTicket(hexToBuffer(encryptedGuess))
  .accounts({
    buyer: wallet.publicKey,
    lottery: rafflePda,
    ticket: ticketPda,
    vault: vaultPda,
    // ...
  })
  .rpc();

// Later: check if won (encrypted comparison)
await program.methods.checkWinner().accounts({...}).rpc();

// Decrypt result
const result = await decrypt([isWinnerHandle], { address, signMessage });
const won = result.plaintexts[0] === "1";
console.log("Did I win?", won ? "YES!" : "No");

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Source Code

git clone https://github.com/Inco-fhevm/raffle-example-solana.git