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SeedSigner

Open-source, DIY Bitcoin signing device built from commodity hardware. Designed for air-gapped seed generation, transaction signing, and multisig coordination without trusting proprietary hardware.

What It Is​

SeedSigner is a Bitcoin-only hardware signer assembled from a Raspberry Pi Zero W, a Waveshare 1.3-inch LCD HAT, and a Pi Camera Module. It runs purpose-built firmware that generates and stores seeds, displays QR codes for transactions, and signs PSBTs entirely offline.

Key Features​

  • Air-gapped signing: No WiFi, Bluetooth, or USB data used after initial setup. Transactions flow in and out via QR codes.
  • Seed generation: Creates BIP39 seed phrases using camera entropy (image noise) or manual dice rolls.
  • Multisig support: Generates xpubs, coordinates multisig setups, and signs PSBTs for multisig transactions.
  • Verifiable build: All components are off-the-shelf and firmware is open source. Anyone can inspect, build, and flash.
  • Low cost: Approximately $50-70 in parts vs. $100-200+ for commercial hardware wallets.

Security Model​

SeedSigner is designed for users who want to verify every layer of their signing stack:

  • No closed-source chips or secure elements
  • No vendor-update mechanism that could be coerced
  • Entire stack inspectable: hardware schematics, firmware code, build process
  • Trade-off: no tamper-resistant enclosure or secure element. Physical security and supply-chain verification are the user's responsibility.

Use Cases​

  • Cold storage signing: Generate a seed, record the words, then power down. Sign transactions later by booting from SD card.
  • Multisig coordinator: Use SeedSigner as one key in a 2-of-3 or 3-of-5 setup alongside commercial hardware wallets.
  • Workshop/education: Build and understand a hardware wallet from first principles at meetups or self-study.

Relation to Round Rock Bitcoiners​

  • Featured in node-building and custody-focused meetups as part of the DIY/maker ethos
  • Significantly lower cost than commercial hardware wallets; fits the community's focus on accessible self-custody
  • Demonstrates the distinction between hardware wallets (proprietary, closed) and verifiable signing devices (open, inspectable)

Resources​

See also​

  • [concepts/custody-models.md] — trade-offs between hot, warm, and cold storage
  • [entities/simple-proof.md] — complementary Bitcoin-native security tools
  • [entities/jade.md] — commercial hardware wallet alternative with different trust assumptions