ZKLINK Documentation

Introduction

ZKLINK is a privacy protocol built natively for Solana that enables fully private transactions using zero-knowledge proofs (zk-SNARKs). Unlike other privacy solutions, ZKLINK hides the sender, receiver, and amount of every transaction.

Quick Start

Get started with ZKLINK in just a few steps. No coding required for basic usage.

How It Works

ZKLINK uses a combination of cryptographic techniques to achieve privacy while maintaining the security guarantees of the Solana blockchain.

The Shielded Pool

When you shield SOL, your funds enter a shared "shielded pool." This pool contains the combined funds of all ZKLINK users, making it impossible to trace individual balances.

Commitments & Nullifiers

Each shielded transaction creates a commitment (a cryptographic hash representing your funds) and a nullifier (a unique value that prevents double-spending). These are stored on-chain but reveal nothing about the actual transaction.

// 1. Shield: Public SOL → Shielded Pool
PublicSOL → createCommitment(amount, secret) → ShieldedBalance

// 2. Transfer: Prove ownership without revealing details
generateProof(oldCommitment, newCommitment, nullifier)
→ Verifier checks proof on-chain
→ ShieldedBalance transferred privately

// 3. Unshield: Shielded Pool → Public SOL
proveOwnership(commitment) → PublicSOL returned

Zero-Knowledge Proofs

ZKLINK uses zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge) to prove transaction validity without revealing any details.

What is a zk-SNARK?

A zk-SNARK allows you to prove that you know something (like a secret key) without revealing what that something is. In ZKLINK's case, you prove:

• You own the funds you're spending
• You're not double-spending
• The transaction amounts balance correctly

All without revealing who you are, who you're sending to, or how much.

Proof Generation

Proofs are generated off-chain on your device, then submitted to Solana for on-chain verification. This keeps proof generation fast while maintaining trustless verification.

Privacy Model

Understanding what ZKLINK hides and what it doesn't is crucial for using it effectively.

What's Hidden

• Sender address — Nobody knows who sent the transaction
• Receiver address — Nobody knows who received the funds
• Amount — The transaction amount is encrypted
• Account balance — Your shielded balance is private

What's Visible

• Transaction occurred — Observers can see a ZKLINK transaction happened
• Approximate timing — When the transaction was included in a block
• Gas fees — The fee paid to Solana validators

SDK Setup

Integrate ZKLINK into your application using our TypeScript SDK.

Installation

# Using npm
npm install @zklink-protocol/sdk

# Using yarn
yarn add @zklink-protocol/sdk

# Using pnpm
pnpm add @zklink-protocol/sdk

Basic Usage

import { ZklinkClient, Keypair } from '@zklink-protocol/sdk';

// Initialize the client
const zklink = new ZklinkClient({
  network: 'mainnet-beta',
  wallet: yourWalletAdapter,
});

// Shield SOL (deposit into private pool)
const shieldTx = await zklink.shield({
  amount: 10 * 1e9, // 10 SOL in lamports
});

// Send private transfer
const transferTx = await zklink.privateTransfer({
  recipient: recipientPublicKey,
  amount: 5 * 1e9, // 5 SOL
});

// Unshield SOL (withdraw from private pool)
const unshieldTx = await zklink.unshield({
  amount: 5 * 1e9,
  recipient: yourPublicKey,
});

Frequently Asked Questions

Is ZKLINK fully non-custodial?

Yes. Your private keys never leave your device. ZKLINK's smart contracts are non-upgradeable and cannot access your funds — only you can move your shielded SOL.

What happens if ZKLINK goes offline?

Your funds remain safe on-chain. The smart contracts are immutable and will continue to function. You can always unshield your funds using any compatible interface or directly via the contracts.

Is ZKLINK audited?

Yes. ZKLINK has been audited by leading security firms. Audit reports are available in our Security section.

What are the fees?

ZKLINK charges a small protocol fee (0.1%) on shield and unshield operations. Private transfers between shielded addresses have no protocol fee — you only pay Solana network fees.

Can I use ZKLINK with hardware wallets?

Yes. ZKLINK works with Ledger and other hardware wallets through Phantom, Solflare, and other wallet adapters.

Security

Security is our top priority. Here's how we keep your funds safe.

Audits

Our smart contracts and cryptographic circuits have been audited by:

• OtterSec — Smart contract security audit
• Trail of Bits — Cryptographic circuit review
• Zellic — Full protocol audit

Bug Bounty

We run a bug bounty program with rewards up to $100,000 for critical vulnerabilities. If you find a security issue, please report it responsibly.