VeilPay

Private Payments with Public UX on Solana

VeilPay is a privacy-first payment protocol on Solana that enables fully private SPL token transfers while preserving wallet-like UX, notifications, and auditability. Built with Arcium confidential SPL and Helius privacy-safe indexing.

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Problem Statement

On Solana today, every payment leaks sensitive financial data:

• Wallet balances are public
• Transfer amounts are visible
• Wallets can be clustered through address reuse
• Indexers expose full transaction history

VeilPay solves this by combining encrypted balances with privacy-safe metadata indexing.

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Architecture

Core Components

Arcium Confidential SPL (cSPL) - Encrypted balances and transfers
Helius Privacy-Safe Indexing - Activity feeds without exposing sensitive data
Stealth Addresses - Prevents wallet clustering
Selective Disclosure Proofs - Optional compliance and audits

Privacy Model

Private:

• Wallet balances (encrypted with Arcium MPC)
• Transfer amounts (never revealed on-chain)
• Sender/receiver identities (hidden via commitments and stealth addresses)

Public:

• Transaction existence (timestamp and slot)
• Validity proofs (cryptographic commitments)
• Event metadata (non-sensitive data for indexing)

Account Structure

ConfidentialBalance Account:
- owner_commitment: [u8; 32]  (Hashed owner pubkey)
- encrypted_balance: [u8; 64] (Arcium encrypted value)
- nonce: u64                  (Replay protection)
- bump: u8                    (PDA bump seed)

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Features

Core

• Confidential balance storage using Arcium MPC
• Private transfers with encrypted amounts
• Stealth addresses for recipient privacy
• Replay protection via nonces
• Owner verification through commitments
• Privacy-safe event emission for indexing

Security

• End-to-end encryption for sensitive data
• Range proofs for balance validation
• Zero-knowledge proofs for correctness
• Access control via owner commitments

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Installation

Prerequisites

• Rust 1.75+
• Solana CLI 1.18+
• Anchor 0.32+
• Node.js 18+

Setup

# Clone repository
git clone <repository-url>
cd veilpay

# Build program
cd veilpay
anchor build

# Run tests
anchor test

# Setup frontend
cd ../frontend
npm install
cp .env.example .env.local
# Edit .env.local with your configuration
npm run dev

Environment Variables

NEXT_PUBLIC_SOLANA_NETWORK=devnet
NEXT_PUBLIC_RPC_URL=https://api.devnet.solana.com
NEXT_PUBLIC_PROGRAM_ID=your_program_id
NEXT_PUBLIC_HELIUS_API_KEY=your_helius_key
NEXT_PUBLIC_ARCIUM_API_KEY=your_arcium_key

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Usage

Initialize Balance

const balancePda = PublicKey.findProgramAddressSync(
  [Buffer.from("balance"), owner.publicKey.toBuffer()],
  program.programId
)[0];

await program.methods
  .initBalance()
  .accounts({
    confidentialBalance: balancePda,
    owner: owner.publicKey,
    systemProgram: SystemProgram.programId,
  })
  .signers([owner])
  .rpc();

Private Transfer

const encryptedAmount = encryptAmount(100);
const commitmentHash = generateCommitmentHash(encryptedAmount, nonce, recipientPubkey);
const encryptedTag = generateEncryptedTag(recipientPubkey, senderSecret);

await program.methods
  .privateTransfer(encryptedAmount, new BN(nonce), commitmentHash, encryptedTag)
  .accounts({
    senderBalance: senderBalancePda,
    receiverBalance: receiverBalancePda,
    sender: sender.publicKey,
  })
  .signers([sender])
  .rpc();

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Testing

cd veilpay
anchor test

Test coverage includes:

• Mint initialization
• Balance initialization
• Private transfers (success and error cases)
• Replay attack prevention
• State consistency validation
• Integration scenarios

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Deployment

Devnet

cd veilpay
anchor build
anchor deploy --provider.cluster devnet

Mainnet

anchor build
anchor deploy --provider.cluster mainnet-beta

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Security

VeilPay implements multiple security layers:

1. Encryption - All balances encrypted with Arcium MPC
2. Access Control - Owner commitment verification and signature requirements
3. Privacy - Stealth addresses and encrypted tags prevent clustering
4. Replay Protection - Nonce-based transaction validation

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Project Structure

veilpay/
├── veilpay/              # Solana Program
│   ├── programs/
│   │   └── veilpay/
│   │       └── src/
│   │           ├── instructions/
│   │           ├── state/
│   │           ├── utils/
│   │           └── lib.rs
│   └── tests/
│
└── frontend/             # Next.js Frontend
    ├── app/
    ├── components/
    ├── contexts/
    └── lib/

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Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests for new functionality
5. Ensure all tests pass
6. Submit a pull request

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License

MIT License - see LICENSE file for details.

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Documentation

• PROJECT_SUMMARY.md - Detailed project overview
• FRONTEND_SETUP.md - Frontend setup guide
• TEST_COVERAGE.md - Test coverage details
• IMPLEMENTATION_SUMMARY.md - Implementation guide

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External Resources

• Solana Documentation
• Anchor Documentation
• Arcium Documentation
• Helius Documentation

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Built with ❤️ for Solana - Making privacy practical, one transaction at a time.