SEEL

Privacy-preserving income attestation on Solana — prove your real-world income with client-side ZK proofs and unlock higher LTV borrowing on DeFi, without revealing any financial data.

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How It Works

1. User connects to Plaid via OAuth — income data stays in the browser
2. A Circom Groth16 ZK circuit runs locally and answers: "Is my 6-month average income above the threshold?"
3. The proof (no names, no exact figures, no employer) is sent to the backend for verification
4. User pays a small USDC attestation fee via x402
5. A Soulbound SPL Token-2022 is minted on Solana — valid for 30 days, non-transferable
6. Lending protocols (Kamino, Save) read the token and unlock a higher LTV

Raw income data never leaves the client.

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Architecture

Browser
  ├── OAuth (Plaid)                income data stays client-side
  └── Circom Groth16 (snarkjs)     ZK proof generated locally

Backend (Node.js + TypeScript, port 3001)
  ├── /auth      OAuth callback, session token
  ├── /income    Plaid income data (never forwarded to logs)
  ├── /proof     snarkjs Groth16 proof verification
  ├── /payment   x402 USDC attestation fee
  └── /solana    Anchor program interaction, token minting

Solana (devnet)
  ├── Anchor Program   verify Groth16 proof (BN254), mint/expire/revoke attestation
  └── SPL Token-2022   Soulbound (NonTransferable) attestation token

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Income Tiers

Tier	Monthly Average (6-month floor)	LTV
1	>= $2,000	75%
2	>= $5,000	80%

The circuit checks all 6 months have positive income and computes the floor average. The threshold is a private input — the verifier only sees the resulting tier.

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Tech Stack

Layer	Technology
ZK Circuit	Circom 2.0 + snarkJS (Groth16, BN254)
Solana Program	Rust, Anchor 0.30, SPL Token-2022
Backend	Node.js 18+, TypeScript, Express
Frontend	Next.js 14, Tailwind CSS
Wallet	Solana Wallet Adapter (Phantom, Solflare)
Income APIs	Plaid
Payment	x402 (USDC micropayment)
DeFi	Kamino SDK

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Project Structure

seel/
├── circuits/
│   └── income_proof_circom/   Circom circuit + trusted setup artifacts
├── programs/seel/             Anchor program (Rust)
├── backend/                   Node.js API
├── frontend/                  Next.js app
└── sdk/                       Integration SDK for lending protocols

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Getting Started

Prerequisites

• Node.js 18+
• Rust + Anchor CLI 0.30
• Solana CLI (devnet)
• circom + snarkJS (for circuit setup)

Backend

cd backend
cp .env.example .env   # fill in your credentials
npm install
npm run dev

Frontend

cd frontend
npm install
npm run dev

Anchor Program

anchor build                              # production build
anchor build --features verify-skip      # local testing only — never deploy
anchor deploy --provider.cluster devnet

Never build for production with --features verify-skip.

Circom Circuit

cd circuits/income_proof_circom
npm run setup   # compile, trusted setup, export verification key
# artifacts land in frontend/public/circuits/ automatically

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Environment Variables

Copy backend/.env.example to backend/.env and fill in:

Variable	Description
PLAID_CLIENT_ID	Plaid API client ID
PLAID_SECRET	Plaid API secret
PLAID_ENV	sandbox or production
SESSION_SECRET	Express session secret (random string)
SOLANA_RPC_URL	Solana RPC endpoint
SEEL_PROGRAM_ID	Deployed Anchor program address
USDC_MINT	USDC mint address (devnet or mainnet)
BACKEND_KEYPAIR_PATH	Path to Solana keypair file
BACKEND_WALLET_ADDRESS	Solana address to receive attestation fees

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Deployed Addresses (Devnet)

Resource	Value
Program ID	DwiHe1VWW9KXeWXJFaRFoMNzPt3mVs2Ac84gPbaeBkoJ
USDC Mint	4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU

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Privacy Guarantees

• Income figures are private circuit inputs — they never leave the browser
• The server receives a proof and public outputs only (tier: 1 or 2)
• API responses containing income data are never logged on the server
• The on-chain token stores only tier, timestamps, and a proof hash