Introduction

What are stealth addresses?

Stealth addresses are a cryptographic technique that enables unlinkable payments on public blockchains. Every time someone sends you SOL, the payment goes to a unique, one-time address that only you can detect and spend from.

Unlike regular wallet addresses where your entire transaction history is publicly visible, stealth addresses ensure that no outside observer can determine that two payments went to the same person.

The privacy stack

Cloak v1.0 provides three layers of privacy:

How it works

1. Receiver generates a stealth meta-address (spending + viewing keypairs) and shares the public portion.
2. Sender uses ECDH with the receiver's public meta-address to derive a unique one-time stealth address and an ephemeral keypair.
3. Sender transfers SOL to the stealth address and publishes the ephemeral public key on-chain via an Anchor announcement PDA.
4. Receiver scans announcement PDAs, uses their viewing key to detect which payments are addressed to them, then derives the spending key to claim the funds.

Quick example

use cloak_sdk::{
    StealthMetaAddress, PublicMetaAddress,
    StealthPayment, StealthKeypair, Scanner,
};

// Receiver: generate identity
let meta = StealthMetaAddress::generate();
let public_addr = meta.to_public_string();

// Sender: create stealth payment
let recipient = PublicMetaAddress::from_string(&public_addr)?;
let payment = StealthPayment::create(&recipient, 1_000_000_000)?;
// → payment.stealth_address (where to send SOL)
// → payment.ephemeral_pubkey (publish on-chain)

// Receiver: detect and spend
let keypair = StealthKeypair::derive(&meta, &payment.ephemeral_pubkey)?;
let solana_kp = keypair.to_solana_keypair()?;
// Sign transactions with solana_kp

On-chain program

Cloak includes an Anchor program deployed on Solana Devnet with 6 instructions: