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Verifiable Random Function (VRF) System

Our gacha pack system uses Verifiable Random Function (VRF) technology to ensure completely fair and tamper-proof randomness for all pack openings.

How It Works​

1. Deterministic Input Creation​

When you open a pack, the system combines two pieces of data:

  • Your unique pack memo (UUID assigned when you purchase)
  • Your transaction signature (generated by your wallet when confirming the transaction)

2. VRF Proof Generation​

This combined input is processed through our VRF algorithm (ECVRF-SECP256K1-SHA256) using our private key to generate:

  • A cryptographic proof
  • A random number (1 to 100,000,000) that determines your NFT

3. Immutable Storage​

Both the proof and roll number are stored in our database, but also stored permanently on the blockchain.

Why This Is Trustworthy​

  • User-Controlled Randomness: Your wallet's transaction signature is unique and unpredictable - we cannot influence or predict it
  • Deterministic: Given the same memo + transaction signature, the VRF will always produce the same result
  • Tamper-Proof: Once your transaction is confirmed, the randomness cannot be changed or manipulated
  • Cryptographically Secure: Uses industry-standard elliptic curve cryptography

Verification​

Anyone can verify the fairness of any pack opening:

API Verification​

Use our verification endpoint:

GET /api/vrf/verify?memo=YOUR_MEMO_HERE

This returns:

  • valid: Whether the VRF proof is cryptographically valid
  • rollMatches: Whether the stored roll matches the calculated roll
  • proof: The VRF proof for this pack
  • publicKey: Our VRF public key
  • transactionSignature: Your unique transaction signature

Manual Verification​

  1. Take the memo + transaction signature
  2. Hash them together using SHA-256
  3. Use our public key to verify the VRF proof
  4. Calculate the roll from the proof hash

Technical Details​

  • Algorithm: ECVRF-SECP256K1-SHA256-TAI
  • Input: SHA-256(memo + transaction_signature)
  • Output: Deterministic 32-byte hash converted to roll (1-100,000,000)
  • Public Key: Available in verification responses

Transparency​

Every pack opening includes:

  • Immutable transaction record on Solana blockchain
  • VRF proof stored in our database
  • Public verification endpoint for all users
  • Open-source verification logic

This system ensures that neither we nor anyone else can manipulate your pack results after your transaction is confirmed.