Game Boy Seed Signer

Development demo only. Never use real funds, a valuable seed phrase, private keys, passphrases, or production transactions with this repository. It is an unfinished learning project, not a secure hardware wallet.

This repository explores Bitcoin-related workflows on classic Game Boy hardware. It contains early Python experiments, historical ROM-header work, and an actively developed Game Boy Pocket interface for learning about offline workflows.

Security Status

This project does not provide secure key storage, tamper resistance, a secure element, reviewed secp256k1 signing, PSBT parsing, transaction signing, address derivation, or safe production backup handling.

• Never use real funds.
• Never enter a valuable recovery phrase.
• Never place private material in a .sav file, SD card, chat, issue, or screenshot.
• Treat every ROM and helper here as development software only.

Project Layout

• gameboy_wallet/ - Current Game Boy Pocket ROM, build scripts, release snapshots, and emulator/hardware test target.
• gameboy_wallet/releases/ - Versioned, checksummed ROM snapshots for rollback.
• m17_wallet/ - Separate M17/MinUI native signer-development target with host-side PSBT envelope tests.
• prototype/ - Python concepts for wallet and signing workflows.
• roms/ - Earlier ROM-header and cartridge boot experiments.
• docs/ - Project notes and planning.

Current Game Boy ROM

The Pocket ROM includes a navigable monochrome interface, dice-entry audit mode, volatile BIP39-word display for UI research, a Game Boy Pro+ SRAM inbox experiment, and a QR link to this repository. None of these features constitute a safe signer or wallet.

Build the current ROM with GBDK-2020:

cd gameboy_wallet
make

The current testable artifact is gameboy_wallet/releases/v0.6.1/pocket_btc.gb. Verify its checksum before testing:

sha256sum gameboy_wallet/releases/v0.6.1/pocket_btc.gb

See gameboy_wallet/README.md for controls, build requirements, the Pro+ save-file experiment, and important limitations.

M17 Development Target

The SJGAM M17 target runs as a separate MinUI .pak package and is not connected to the Game Boy code. Its first milestone is strict, read-only PSBT file handling; it does not currently parse transactions, decrypt a seed vault, sign, or export signed PSBTs. See m17_wallet/README.md.

Development Workflow

Every successful hardware or emulator build is preserved in gameboy_wallet/releases/vX.Y.Z/ with its ROM, source, generated assets, scripts, and SHA-256 checksum. Do not overwrite an existing release; create a new version for each testable change.

Roadmap

• Improve Game Boy UI and hardware behavior through emulator and Pocket testing.
• Keep file transport and seed-session experiments clearly separated from production wallet claims.
• Add cryptographic functionality only with published test vectors and independent review.
• Do not use this project with real Bitcoin funds until a complete security design and audit exist.