Clench Wallet

Clench is a Bitcoin-only, non-custodial Bitcoin wallet for Android. It uses Bitcoin Dev Kit and stores wallet data locally on the device.

Wallet features:
- Create single-sig and multisig wallets.
- Import watch-only wallets from descriptors.
- Create or restore BIP-39 seed phrase wallets with an optional passphrase.
- Use native SegWit, nested SegWit, legacy, and Taproot script types.
- Connect to Electrum servers, including personal servers and Tor SOCKS5 routes.
- Use coin control, UTXO freezing, labels, batch payments, RBF fee bumping, CPFP, cancel replacement attempts, raw transaction import, and sweep flows.
- Run node diagnostics for Electrum route, Tor mode, TLS pinning, server version, and tip height.

Hardware-wallet features:
- Exchange PSBTs by animated QR, BBQr, an intentional NFC tap, microSD/user-selected file import, or signed-return import where supported.
- Clench does not communicate with signing devices over USB or Bluetooth. A signer may still use USB for power.
- Work with QR-based signers such as SeedSigner, Keystone, Foundation Passport, and Blockstream Jade. v0.3.28 adds physically unverified protocol presets intended for OneKey Pro, Krux, and Specter DIY; the Krux and Specter DIY presets also include user-selected microSD/file transfer.
- Work with Coldcard Q, Coldcard Mk4, and Coldcard Mk5 transfer paths.
- Check TAPSIGNER NFC Tap Protocol status.
- Sweep SATSCARD active slots with certificate verification and explicit CVC-authenticated unseal confirmation.
- Set up, verify, import, and back up TAPSIGNER cards, and directly sign supported single-signature BIP84 native-SegWit or standard BIP48 native-P2WSH multisig inputs with complete in-app review and returned-signature verification.
- TAPSIGNER payment signing does not support Taproot, legacy, nested SegWit, nonstandard P2WSH, other account paths, or PIN change.
- The OneKey Pro, Krux, Specter DIY, and TAPSIGNER multisig paths have automated coverage but no recorded physical-device acceptance; no model/firmware compatibility claim is made for those new paths.
- Require explicit broadcast confirmation after hardware-wallet signing.

Security and privacy features:
- Encrypt keys with Android Keystore.
- Encrypt the Room application database with SQLCipher. BDK public wallet-state files rely on the Android app sandbox and device encryption.
- Protect wallet access with PIN and biometric authentication where available.
- Validate signed PSBTs and finalized transactions before broadcast.
- Avoid analytics, advertising SDKs, Firebase, Google Play Services, crash reporting services, and account sign-in.

Network use is limited to wallet sync and optional user-triggered fee or price data lookups.

Clench is free software under the MIT License.

Require fresh Android authentication to disable seed/send protections. Reject repeated multisig key material in new policies; warn without changing existing wallets. Harden signing sessions, backup identifiers, QR frames and Electrum input handling. Add explicit signature-collection restart. Update SQLCipher with tested database/WAL upgrade handling. Strengthen signing-secret scope and native dependency checks. Physical-device validation remains outstanding; see release notes for evidence limits