Winner Selection

Our automated smart contract randomly selects a winner once the threshold is met and the raffle has expired. Winner selection is verifiable on the blockchain. Instant winner notification.

Overview

Our raffle system uses a transparent, verifiable, and fair process to select winners. The selection happens entirely on the Solana blockchain, which means it's tamper-proof and publicly verifiable.

The Two-Step Process

We use a two-step process to ensure maximum fairness:

1. Random Ticket Selection: First, our smart contract generates a random winning ticket number

2. Winner Identification: Then, the system identifies which user purchased that ticket

Technical Implementation

Step 1: Random Ticket Drawing

The smart contract uses Solana's SlotHashes as a source of randomness. Here's what happens:

1. The contract accesses the most recent SlotHashes sysvar (system variable) on Solana

2. It extracts the most recent block hash (the first 8 bytes of data)

3. The contract combines this hash with the current timestamp to create a unique seed value

4. Using this seed, it generates a number between 0 and the total number of tickets sold (using modulo operation)

5. This number becomes the winning ticket

This implementation ensures:

• No one (not even us) can predict which ticket will win

• The randomness comes from the blockchain itself

• Anyone can verify the process by checking the transaction on-chain

Step 2: Winner Identification

Once the winning ticket number is determined:

1. The smart contract searches through all entry records to find which entry contains the winning ticket

2. Each entry record contains:

   • The owner's wallet address

   • The ticket count

   • The starting ticket index

3. The entry is found where: starting_index ≤ winning_ticket < (starting_index + ticket_count)

4. The owner of this entry is identified as the winner

Verification

Users can verify this process by:

1. Checking the raffle state on-chain, which includes the winning ticket number

2. Reviewing the transaction where the winner was determined

3. Confirming that their entry's ticket range does or doesn't include the winning number

Example

Let's say a raffle sold 100 tickets total:

• Alice bought tickets 0-9 (10 tickets)

• Bob bought tickets 10-29 (20 tickets)

• Charlie bought tickets 30-99 (70 tickets)

If the random process selects ticket #23:

1. The system identifies that ticket #23 falls within Bob's range (10-29)

2. Bob is declared the winner

3. This result is recorded on-chain and cannot be altered

The probability of winning is directly proportional to the number of tickets purchased - Bob had a 20% chance with his 20 tickets.