Keystone is the closest hardware analogue to Coldstar: transactions cross by QR code, the device never touches USB data or Bluetooth, and the firmware is published. The question is whether you want that model in a $149 appliance or in software you run yourself.
Keystone for the human-operated vault; Coldstar for the automated or delegated signing that a device with a fingerprint reader can't do.
| Coldstar | Keystone 3 Pro | |
|---|---|---|
| Upfront cost | ~$10 — any USB drive. The software is free and MIT-licensed. | $149 (bundle $254.80). |
| Where the key lives | AES-256-GCM encrypted keyfile on a drive you own. Plaintext exists only in memory-locked RAM for the ~100 µs it takes to sign, then is zeroized. | Three secure elements (Microchip ATECC608B, Maxim DS28S60, Maxim MAX32520). Certification level not stated on Keystone's pages. |
| How a transaction reaches the key | Build online → QR (or file) to an offline machine → sign → QR back → broadcast. Fully air-gapped; the drive is storage, not a signer. | QR camera and microSD. No USB data, Bluetooth, Wi-Fi, or NFC. Fully air-gapped. |
| Source code | Open source (MIT) — every line that touches the key is readable on GitHub. | Firmware published (Rust/C) and marketed as 100% open. Caveat from the repo: the MH1903 MCU library ships as a pre-compiled binary for IP reasons. |
| What you trust | Code you can read, plus your own offline machine. No vendor silicon, firmware, cloud, or account. | Published firmware, the SE vendors, one pre-compiled MCU library, and Keystone's release signing. |
| Recovery | Passphrase + encrypted keyfile. The drive is disposable: lose it and the file is useless without the passphrase; re-flash a new one. | BIP39 12/24 words, Shamir backup, passphrase. No cloud recovery. |
| Automation & policy | CLI-first, scriptable, headless. Policy-gated agent signing: limits, allowlists, rate caps, escalation to air-gapped approval. | None. Each transaction is a QR round-trip with fingerprint or PIN approval. |
| Solana wallets | Coldstar CLI and Seeker app. | Solflare extension (firmware ≥1.1.0) and Solflare mobile via QR. |
| Maturity | Beta — independent audit planned before the production release. | Third-generation device; shipping product with an established user base. |
If you like the air-gap model and want it in a box, Keystone is the device to buy. Coldstar is the same model as software: free, MIT-licensed, scriptable, and with no pre-compiled blobs between you and the key.
Keystone and Coldstar agree on the important thing: the key should never be on a machine with a network path, and transactions should cross the gap as data a human can inspect. Keystone implements that with dedicated hardware and a camera; Coldstar implements it with any offline computer and a USB drive holding an encrypted keyfile.
Where they differ is what protects the key at rest. Keystone stores the seed in secure elements, which is strong against physical theft of the device. Coldstar never stores a plaintext key anywhere: the file on the drive is AES-256-GCM ciphertext, and losing the drive costs you nothing without the passphrase.
Keystone is a shipping third-generation product. Coldstar is beta ahead of an independent audit. Weigh that honestly.
Keystone is a purpose-built device; Coldstar is software you run on an offline machine. Keystone protects the seed in secure elements; Coldstar stores only an encrypted file and decrypts into RAM for microseconds. Coldstar is also scriptable and policy-gated, which a device operated by fingerprint is not.
Its firmware is published under an open licence, but the repository notes that one MCU library is included as a pre-compiled binary for IP reasons. Coldstar's signing path is entirely source.
Coldstar shows the decoded transaction on the offline machine's terminal before signing. It is less pretty than a 4-inch touchscreen, and just as inspectable.
Open source, MIT. macOS, Linux, Windows — and on the Solana Seeker dApp Store.
pip install coldstar
Third-party facts were checked against the vendor's own pages on the date above. Pricing and feature sets change; if something here is out of date, tell us and we will fix it.