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name: bitcoin-hardware-krux description: | Krux: DIY airgap signer running on Sipeed M5StickV / Maix Amigo. Open-source, multi-language, stateless. USE WHEN: integrating Krux, evaluating M5StickV-based signers. allowed-tools: Read, Grep, Glob

Krux

Bitcoin-only airgap signer for Sipeed M5StickV and Maix Amigo hardware. Open-source firmware. Stateless: seed enters on use.

Hardware

• Sipeed M5StickV (~$50).
• Maix Amigo (~$80, larger screen).
• Built-in camera + display.
• USB-C charging only (no data).

Operation

1. Power on, boot Krux firmware from internal flash.
2. Enter seed via:
   • 24-word manual entry.
   • SeedQR scan.
   • Tinyseed (metal plate decoder).
3. Sign PSBTs via animated QR.

Features

• Multi-language UI (English, Spanish, French, etc.).
• Multi-output signing (PSBT, message signing).
• BIP39 word entry helper.
• Tiny seed decoder for steel backup plates.

Compatible wallets

• Sparrow.
• Specter.
• BlueWallet (limited).

Use cases

• Cheaper than SeedSigner DIY if you don't have a Pi.
• Educational — explore HW signer internals.
• Privacy-focused — no permanent identity.

Limitations

• Smaller screen (M5StickV).
• Sipeed hardware availability varies by region.
• No SE — same caveat as SeedSigner.

See also

• seedsigner/SKILL.md
• specter-diy/SKILL.md
• passport/SKILL.md