Get started
Connect your wallet, turn on privacy with one signature, and register your privacy key so that you can hold NOIR in private notes and receive private sends.
Turning on privacy takes one signed message and one small transaction. After that, you can buy NOIR straight into a private note, shield NOIR you already hold, and receive private sends from other people.
What you need
| Item | Why |
|---|---|
| A browser wallet that signs with an ordinary key (an EOA), such as MetaMask | It signs the activation message and every private spend. See Supported wallets. |
| A little ETH on Robinhood Chain | Registration, purchases, approvals and shields are normal transactions paid from your address. |
The app talks to the wallet injected in the browser. On a phone, open the app inside your wallet's own browser.
Turn on privacy
Connect your wallet
Press Connect wallet and approve the connection. The app asks the wallet to switch to Robinhood Chain (chain ID 4663), and to add the network if it does not know it yet.
Sign the activation message
Press Turn on privacy. Your wallet shows a Sign-In with Ethereum message. It costs no gas. It names the app's domain and the address of the noircash vault (see Deployments), and reads like this:
noircash.app wants you to sign in with your Ethereum account:
0xYourAddress
Activate privacy for the noircash vault 0xvaultaddress. This signature derives the keys that reveal your private balance. Sign it only on noircash.app.The app derives your privacy keys from this signature: a viewing key that finds and decrypts your notes, and a nullifier key that proves you own them. You never write down a new seed phrase. See Keys.
Sign it a second time (first use only)
The first time, the wallet asks for the same signature again. The app compares the two. If they differ, your wallet does not sign deterministically, so your keys would not come back next time and any note sent to you would be lost. The app then refuses the wallet with an error and registers nothing.
On later visits the app asks for one signature and checks that it gives the key already registered for your address.
Register your privacy key
The app sends one transaction from your address to the vault. It publishes your owner key and your viewing public key in the vault's on-chain registry. You pay its gas in ETH.
From then on, other people can send you NOIR privately: their app reads your keys from the registry and creates a note that only you can find and spend. NOIR that reaches your address in an ordinary transfer or purchase is still public NOIR: shield it to make it private.
The activation signature reveals every note you own to whoever has it. It cannot move them: each spend needs a fresh confirmation in your wallet. Sign it only on the official app domain. See Staying private.
What the app keeps
- Your keys stay in memory only. Nothing is saved to the browser's storage or sent to a server.
- The session survives moving between pages of the app, such as the wallet and the history.
- Reloading or closing the tab ends the session. Connect again and sign the message once more: the same wallet gives the same keys, so your notes come back.
- Nothing to back up. Your notes are stored on-chain, encrypted. On any device, the same wallet and the same signature find them again.
Registration is public: anyone can see that your address has activated privacy. It reveals nothing about what you hold.
Next
- Buy NOIR straight into a private note.
- Shield NOIR you already hold.
- Read your balance and history.