Keystone

Is Keystone safe?

Yes, for keeping keys offline, with a caveat about how much outside testing it has had. The Keystone 3 Pro creates your keys on the device, stores them behind three secure elements and signs transactions by showing and scanning QR codes, so your phone or computer never touches the key. Its firmware is public under the MIT licence. We found no theft, CVE or data leak tied to Keystone. We score it 83/100, a B.

What holds it back is depth of scrutiny rather than any known failure. Keystone sells far fewer devices than Ledger or Trezor, the one published third-party audit covered only its Zcash code, and part of the code on its main chip is a closed binary from the chip maker.

How Keystone keeps your keys offline

The Keystone 3 Pro is a pocket-sized device (62 by 100 mm) with a 4-inch touchscreen, a camera and a fingerprint reader. You pair it with a software wallet such as MetaMask, Sparrow or BlueWallet by scanning a QR code that holds only public keys. To send, the software wallet shows the unsigned transaction as a QR code, the Keystone scans it, you check and approve it on the device, and the Keystone shows a signed QR code back. A microSD card can do the same job. There is a USB-C port for charging and WebUSB firmware updates, and Air-Gapped Mode switches its data connection off.

The README lists the hardware: an MH1903 main chip plus three secure elements from two makers, a Microchip DS28C50, a Maxim MAX32520 and a Microchip ATECC608A. Keystone says opening the case triggers anti-tamper circuits that wipe the device. Backups are standard BIP-39 words or Shamir shares, and you can add a passphrase, use dice rolls for entropy, set up multisigMultisigA crypto wallet that needs approval from several keys to move funds, for example any 2 of 3, rather than from a single key.More in the glossary and hold up to three separate seeds on one device.

That puts it in the top band for key security, at 88. It sits just below Trezor at 90 for one reason the Coldcard case made urgent: we found no independent review of how Keystone generates seeds.

Has anyone checked the seed generator?

Partly. In the public firmware, the function that creates a new seed takes random bytes from the main chip's generator and from two of the secure elements, and mixes them with HKDF and a hash of the device password. Combining several sources means one weak chip should not make the seed guessable on its own. That is a sound design on paper.

The only published audit we could find is narrower. Least Authority reviewed the Keystone firmware and SDKs for the Zcash community between January and March 2025. It looked at Zcash key generation, signing and the QR protocol, found five suggestions and no security issues, and said it "did not identify any areas of concern" in the use of randomness within that scope. Keystone's blog says SlowMist audited the Keystone 3 Pro firmware and Keylabs the hardware, but we could not find either report published. A full review of the general seed path would close the gap.

Open source, with one closed piece

The Keystone 3 firmware has been on GitHub since September 2023. GitHub's licence label shows "NOASSERTION", but the LICENSE file itself is the MIT licence, held by Yanssie HK Limited. Hardware schematics and the bill of materials are in the same repo, and a Docker-based guide explains how to build a release and compare its checksum with the one on your device. WalletScrutiny lists the Keystone 3 Pro as "source available" and has worked on a build script, but has not marked it reproducible.

Two things keep transparency at 76. A library from the main chip's maker ships only as a compiled file because of the vendor's licence terms, which Keystone states openly. And the bug bounty has a clear scope but no published reward amounts; payouts are at Keystone's discretion.

Will Keystone stop me signing a drainer?

It helps. You confirm every transaction on the device's own screen, which a hacked phone cannot change. For Ethereum contract calls, Keystone decodes the data using an ABI pack and ENS database it publishes on GitHub, so you see the function and the addresses instead of raw hex. It does not simulate the outcome, so a valid-looking "approve" for an unknown contract still needs a careful read. Bitcoin transactions show outputs and amounts plainly. We score this 83.

How to stay safe with a Keystone

1. Buy from keyst.one or an authorised reseller, and check that the device has not been set up before.
2. Generate the seed on the device, write it on paper or metal, and never type it into a phone, computer or website.
3. Leave Air-Gapped Mode on; you only need USB for firmware updates.
4. Read the address and amount on the Keystone's screen, not on your phone, before approving.
5. Add a passphrase for larger holdings, and treat the extra seed slots as spending wallets, not your savings.

How we scored it

Key security (88) is Keystone's strongest factor: keys stay on a device with three secure elements that signs without a data cable. Security record (82) reflects a clean record on a smaller, less tested user base. Transparency (76) is the weakest: the firmware is MIT-licensed and rebuildable, but the only published audit covered Zcash code and one chip library is closed. Keystone scores level with Trezor and above SafePal, the other QR-based hardware walletHardware walletA small dedicated device that stores crypto private keys offline and signs transactions inside the device, so the keys never touch your computer.More in the glossary we cover, mainly because its firmware is fully published.