⬡ K E T E R

Privacy-Preserving Compliance for Security Tokens

Where Zero-Knowledge Meets Regulatory Compliance

Problem • How It Works • Architecture • Quick Start • Contracts • Team

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🔮 The Problem

MiCA requires identity verification. GDPR forbids storing it on-chain. Blockchain demands transparency.

Security tokens under MiCA (Markets in Crypto-Assets) regulation must comply with KYC/AML requirements. But storing personal identity data on a public blockchain violates GDPR. This creates an impossible trilemma:

        ┌─────────────────┐
        │   COMPLIANCE    │  ← MiCA requires investor verification
        │   (KYC/AML)     │
        └────────┬────────┘
                 │
    ┌────────────┼────────────┐
    │            │            │
    ▼            ▼            ▼
┌────────┐ ┌─────────┐ ┌──────────┐
│ PRIVACY│ │TRANSPAR- │ │ ON-CHAIN │
│ (GDPR) │ │  ENCY   │ │ IDENTITY │
└────────┘ └─────────┘ └──────────┘
    ✗            ✗            ✗
    
    Traditional approaches fail all three.

Keter solves this. Using zero-knowledge proofs, investors prove they meet compliance requirements without revealing any personal data on-chain.

🧬 How It Works

Keter uses Noir circuits compiled and proven directly in the browser via NoirJS. No backend. No trusted server. Pure client-side ZK.

┌──────────────────────────────────────────────────────────┐
│                      INVESTOR BROWSER                     │
│                                                          │
│  ┌─────────────┐    ┌──────────────┐    ┌─────────────┐ │
│  │  KYC Data    │───▶│  Noir Circuit │───▶│  ZK Proof   │ │
│  │  (private)   │    │  (NoirJS)    │    │  (public)   │ │
│  └─────────────┘    └──────────────┘    └──────┬──────┘ │
│                                                 │        │
└─────────────────────────────────────────────────┼────────┘
                                                  │
                                                  ▼
┌──────────────────────────────────────────────────────────┐
│                    ETHEREUM (SEPOLIA)                     │
│                                                          │
│  ┌────────────────┐  ┌───────────────┐  ┌─────────────┐ │
│  │ UltraVerifier  │  │   Registry    │  │ KeterToken  │ │
│  │ (verify proof) │──│ (store root)  │──│ (ERC-20 ST) │ │
│  └────────────────┘  └───────────────┘  └─────────────┘ │
│                                                          │
└──────────────────────────────────────────────────────────┘

The Flow

1. Investor inputs KYC data (name, age, address, investor type, etc.) in the browser
2. Noir circuit hashes the data into a Poseidon Merkle leaf and generates a ZK proof of compliance
3. Proof is submitted on-chain to the UltraVerifier contract
4. Registry validates the Merkle root and registers the investor's wallet
5. KeterToken (security token) checks the Registry before allowing transfers

🔒 Zero personal data touches the blockchain. Ever.

⚙️ Architecture

keter/
├── circuits/                  # Noir ZK circuits
│   ├── src/
│   │   └── main.nr           # Compliance proof circuit
│   ├── Nargo.toml             # Noir project config
│   └── Prover.toml            # Prover inputs
│
├── contracts/                 # Solidity smart contracts
│   ├── KeterToken.sol         # ERC-20 security token
│   ├── Registry.sol           # Compliance registry
│   └── UltraVerifier.sol      # Auto-generated Noir verifier
│
├── frontend/                  # React frontend (client-side proving)
│   ├── src/
│   │   ├── components/        # UI components
│   │   ├── hooks/             # NoirJS proof generation hooks
│   │   ├── circuits/          # Compiled circuit artifacts
│   │   ├── utils/             # Helpers & contract ABIs
│   │   └── App.tsx            # Main application
│   ├── package.json
│   └── vite.config.ts
│
├── .env.example               # Environment template
└── README.md

🛠 Stack

Layer	Technology	Purpose
ZK Circuits		Compliance proof generation
Proof Engine		Client-side proof compilation & proving
Smart Contracts		On-chain verification & token logic
Frontend		User interface
Styling		UI framework
Build		Bundler
Wallet		Wallet connection & tx signing
Network		Deployment network
Hash		ZK-friendly hashing (Merkle tree)

📜 Deployed Contracts

Network: Ethereum Sepolia Testnet

Contract	Address	Role
Registry	0x4FF9F411b531a14Cd91e6ce0418A3C500E1951F9	Stores Merkle roots & compliance status
UltraVerifier	0xEC3DE79cF2Dd56a5Ae637E03390e52b557C65f93	Verifies Noir ZK proofs on-chain
KeterToken	0x270463352d42B4B891E0605CAC0f5B9Dd5437cF7	ERC-20 security token with compliance gates

🚀 Quick Start

Prerequisites

• Node.js >= 18
• Nargo >= 1.0.0-beta
• A browser wallet (MetaMask) connected to Sepolia

1. Clone & Install

git clone https://github.com/your-org/keter.git
cd keter

2. Setup Environment

cp .env.example .env

3. Compile Circuits

cd circuits
nargo compile
cd ..

4. Launch Frontend

cd frontend
npm install
npm run dev

Open http://localhost:5173 and connect your wallet.

🔑 Environment Variables

# .env.example

# ── Network ──────────────────────────────────────
VITE_RPC_URL=https://eth-sepolia.g.alchemy.com/v2/YOUR_KEY
VITE_CHAIN_ID=11155111

# ── Contracts ────────────────────────────────────
VITE_REGISTRY_ADDRESS=0x4FF9F411b531a14Cd91e6ce0418A3C500E1951F9
VITE_VERIFIER_ADDRESS=0xEC3DE79cF2Dd56a5Ae637E03390e52b557C65f93
VITE_TOKEN_ADDRESS=0x270463352d42B4B891E0605CAC0f5B9Dd5437cF7

# ── Circuit ──────────────────────────────────────
VITE_CIRCUIT_PATH=./circuits/target/keter.json

🔐 ZK Circuit

The Noir circuit verifies that an investor:

• Is of legal age (≥ 18) without revealing their actual age
• Resides in an authorized jurisdiction without revealing their country
• Is an accredited investor type without revealing their classification
• Owns the wallet submitting the proof

All private inputs are hashed with Poseidon into a Merkle tree, and the circuit proves membership against a known root — without exposing any leaf data.

┌─────────────────────────────────────────────────┐
│              NOIR CIRCUIT: main()                │
│                                                  │
│  Private Inputs:                                 │
│  ├── name: Field                                 │
│  ├── surname: Field                              │
│  ├── age: Field                                  │
│  ├── address: Field                              │
│  ├── wallet: Field                               │
│  ├── country_code: Field                         │
│  ├── investor_type: Field                        │
│  ├── salt: Field                                 │
│  └── merkle_path: [Field; DEPTH]                 │
│                                                  │
│  Public Inputs:                                  │
│  ├── merkle_root: Field                          │
│  └── min_age: Field                              │
│                                                  │
│  Constraints:                                    │
│  ├── assert(age >= min_age)                      │
│  ├── assert(country ∈ authorized_set)            │
│  ├── assert(investor_type ∈ valid_types)         │
│  └── assert(merkle_verify(leaf, path, root))     │
│                                                  │
└─────────────────────────────────────────────────┘

🤖 AI-Powered KYC Module

⚠️ Status: Not Implemented Yet

A planned module leveraging AI for automated KYC document verification. The AI model will:

• Extract identity fields from uploaded documents (passport, ID)
• Validate document authenticity
• Feed verified data directly into the Noir circuit for proof generation

All processing will remain client-side to maintain the zero-trust architecture.

🏛 Regulatory Context

Regulation	Requirement	Keter Solution
MiCA	KYC/AML for crypto-asset transfers	ZK proof of identity compliance
GDPR Art. 17	Right to erasure of personal data	No personal data stored on-chain
GDPR Art. 25	Data protection by design	Privacy-first ZK architecture
MiFID II	Investor categorization	ZK proof of investor type

👥 Team

0x7manny Smart Contract Engineer

0x11semprez ZK Engineer

Kamil AI / KYC Module

keuchnotkush Security

🏆 Hackathon

Built in 48 hours — February 20-22, 2026

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_{Built with obsession for privacy and compliance.
Keter Protocol — Because privacy is not a feature, it's a right.}