SwitchBitcoin — coordinator-free Bitcoin atomic swaps (pre-alpha)

TESTNET/REGTEST ONLY · NO REAL FUNDS · external cryptographer review pending. Mainnet has no configuration variant — by construction, not by convention.

SwitchBitcoin (formerly "Swap Key", the internal codename) is a pre-alpha wallet implementing v3.16 adaptor-signature atomic swaps: MuSig2 (BIP327) key aggregation, Taproot escrows, TRUC/v3 + P2A anchors, signed-parameter governance, and a pre-armed-refund + second-device watchtower story built around one load-bearing invariant: a funded escrow always has a driven exit — complete or refund — at all costs.

• Website + tester kit: https://switchbitcoin.com
• Tester package: GitHub release v0.1.0-prealpha (zip SHA256 published on the site and in the release notes)
• Binaries: switchbitcoin-cli (the wallet), switchbitcoin-manifest (operator signing tooling — testers never need it)

Verify a release against this repo

switchbitcoin-cli version prints the crate version, the git commit the binary was built from, and the pinned manifest trust root:

fedd62229b6c8a194d6d174d68ad0ce303623cbd49df4b968b9b06ea9e6ec7fe

The embedded commit hash must exist in this repository (releases are tagged), the zip SHA256 must match the site AND the release notes, and the per-file SHA256SUMS inside the package must verify. A binary printing an UNSHIPPABLE banner carries a test trust root and must never be run — report it.

Build from source

Verified host: Windows x86_64-pc-windows-gnu (rustup GNU toolchain + MinGW gcc). Linux/macOS: best-effort, same script.

cargo test                       # default suite
cargo test --features bitcoind   # + the wallet binary and its gates
cargo clippy --all-targets       # clean, both configs
scripts/build-release.sh         # gates -> release build -> shippability
                                 #   gate -> dist/ package + SHA256SUMS

The release script refuses to package a dirty tree, a failing suite, or a binary whose trust-root pin is not the real operator key.

Exact toolchain pins and byte-for-byte release reproduction (pinned rustc via rust-toolchain.toml, --locked, normalized PE timestamp): see BUILDING.md.

Safety posture (read before running anything)

• Testnet4/regtest only. The seed you generate guards worthless coins.
• ~50% of swap attempts refuse and close through refunds BY DESIGN — a role↔CSV safety stop-gate held deliberately until the external cryptographer review clears it. Funds always come back at the refund timelock; retrying is free.
• Settlement parameters arrive ONLY on BIP340-signed, strictly-versioned manifests verified against the compile-time pin — never from config. See docs/params-governance.md.
• Onboarded coins mature behind a dual wall-clock + block-height anchor drawn per coin (privacy decorrelation); shifting a system clock cannot collapse the delay.
• The watchtower can only ever broadcast your own pre-armed refund (or a CPFP bump of it) — it holds no session keys, cannot steal, cannot grief. Design argument: src/wallet/watch.rs module docs.
• The external cryptographer review (adaptor + timelock composition, extraction correctness, nonce lifecycle, role↔CSV pre-commitment) is pending; its review surfaces are deliberately isolated in src/crypto/ and src/signing/.

Naming note (do not "fix")

newkey-* domain-separation tags, NEWKEY_GIT_HASH, the newkey-scaffold folder name, and the skt1 ticket HRP are deliberate spec literals from the protocol lineage (v3.16) and stay verbatim across the SwitchBitcoin rebrand — changing them breaks signed-artifact compatibility.

Where to read

• docs/TESTER-GUIDE.md — the tester walkthrough (limitations banner first; §8 is the dead-device watchtower drill).
• docs/params-governance.md — why params are signed constants, the issuance workflow, and the per-round governance log (v1 → v3).
• docs/artifacts/ — committed live evidence: first live testnet4 swaps, the ≥23 h serve soak, refund + watchtower drills, the tester-round log.
• docs/BUG-REPORT-TEMPLATE.md — how to report what breaks.

License

MIT — see LICENSE.