Keystone Hardware Wallet

NozyWallet supports Keystone as an air-gapped hardware signer for Zcash mainnet Orchard sends. Keystone holds spend authority; NozyWallet builds proved transactions (PCZT), shows QR codes for signing, and broadcasts the signed result.

Network: Keystone integration is mainnet only. Testnet wallets cannot enable Keystone pairing or PCZT sends.

Where to find it in NozyWallet

SurfaceLocation
DesktopSettings → Keystone — pair UFVK, enable signing
Desktop sendsSend tab — when Keystone is enabled, uses prepare → sign → broadcast
Mobile (companion API)Keystone screen from dashboard — same PCZT flow via nozywallet-api
APIGET/POST /api/keystone/* on localhost companion — see API endpoints below

What Keystone does (and does not do)

Keystone roleDetails
Signs spendsAdds Orchard spend authorization to a proved PCZT
Can hold seedTypical setup: mnemonic generated or imported on Keystone
View-only pairingUFVK import lets Nozy sync balance and build unsigned PCZTs
Not supportedDetails
Transparent (t1) sendsOrchard shielded only — recipients must be u1… unified addresses
TestnetMainnet config and mainnet Keystone device required
In-wallet QR scan (desktop)Paste signed PCZT / UR frames, or scan on Keystone device
On-chain multisigThis is PCZT co-signing, not Bitcoin-style m-of-n

Prerequisites

  1. Zcash mainnet wallet in NozyWallet (network: mainnet in config — default).
  2. Zebrad + sync — wallet synced to tip before sending (Zebra Node Setup).
  3. Keystone device set to Zcash mainnet with firmware that supports Zcash PCZT (zcash-pczt UR type).
  4. Matching keys — Keystone must control the same Orchard account as NozyWallet (see setup paths below).

Setup (pairing)

Path A — Seed on Keystone (recommended)

  1. Create or restore your Zcash wallet on Keystone (mainnet).
  2. On Keystone, export the UFVK (unified full viewing key).
  3. In NozyWallet, import or restore the same mnemonic so sync and PCZT building work locally.
    Alternatively, store only the UFVK in Nozy config for watch-only sync if your workflow uses Keystone as the sole signer — spending still requires the seed on Keystone.
  4. Settings → Keystone → Export UFVK (or confirm stored UFVK matches Keystone). Mainnet UFVKs start with uview1.
  5. Import that UFVK on Keystone if not already paired; confirm the same unified receive address (u1…) on both devices.
  6. Enable Keystone.

Path B — Seed in NozyWallet first

  1. Create or restore wallet in NozyWallet (mainnet).
  2. Settings → Keystone → Export UFVK → import on Keystone.
  3. Import the same mnemonic into Keystone so it can sign PCZTs.
  4. Confirm matching u1… receive address.
  5. Enable Keystone.

UFVK is read-only. It can reveal shielded activity to whoever holds it. It cannot spend funds. See Private Key Management.

Sending with Keystone (desktop)

  1. Ensure Settings → Keystone shows Enabled and mainnet.
  2. Open Send — you should see Keystone signing enabled (mainnet).
  3. Enter recipient (u1…), amount, optional memo → Review & prepare.
  4. Prepare for Keystone — proving may take several minutes on first send.
  5. Scan the PCZT QR on Keystone (multiple UR frames if shown — scan all).
  6. Sign on Keystone.
  7. Paste signed PCZT hex or UR frames back into NozyWallet.
  8. Broadcast signed tx — transaction is submitted via your Zebrad node.

Success shows a txid and a link to mainnet.zcashexplorer.app.

Sending with Keystone (mobile + API)

When using the mobile app with nozywallet-api:

  1. Open Keystone from the dashboard.
  2. Enable Keystone and export UFVK for pairing (same as desktop).
  3. Prepare for Keystone → scan UR on device → paste signed data → Broadcast signed tx.

API calls mirror the desktop Tauri commands — useful for automation or custom frontends.

Receiving ZEC

  • Into NozyWallet: Share your Nozy Receive address (u1…). Anyone (including Keystone) can send shielded ZEC to it.
  • From Keystone to NozyWallet: Use Keystone’s send UI with your Nozy receive address, or use the PCZT flow above with Nozy as the builder/broadcaster.

If Keystone and Nozy share the same wallet, synced balance appears in Nozy after compact sync — no separate “receive from Keystone” step.

API endpoints

Local companion only (nozywallet-api, default http://127.0.0.1:3000):

MethodPathPurpose
GET/api/keystone/statusEnabled, UFVK paired, pending send, network
POST/api/keystone/enableEnable/disable Keystone
POST/api/keystone/export-ufvkExport and store Orchard UFVK
POST/api/keystone/prepare-sendBuild proved PCZT + UR frames
POST/api/keystone/complete-sendDecode signed PCZT, broadcast

See API Server Setup for running the companion.

Troubleshooting

ProblemWhat to check
“Keystone requires mainnet”Set network to mainnet in wallet config; disable testnet.
Invalid recipientUse mainnet Orchard unified address (u1…), not t1 or Sapling-only.
Keystone won’t signSeed must match UFVK; device on Zcash mainnet; scan all UR frames.
Broadcast failsSync to tip; Zebrad reachable; signed PCZT not expired (re-prepare if needed).
UFVK mismatchRe-export from the wallet that holds the seed; confirm uview1 on mainnet.
Balance zero after pairRun sync; UFVK alone does not import notes without scan.

More: Common Issues, Desktop Troubleshooting.

Security notes

  • Treat UFVK export like sharing a read-only copy of your shielded history.
  • Verify recipient and amount on Keystone’s screen before signing.
  • Air-gapped signing reduces hot-wallet exposure; proving still runs on the Nozy machine.
  • Back up your mnemonic — Keystone and/or Nozy depending on where the seed lives (Backup Strategies).