Bitcoin Silver Android Wallet

Mobile wallet for BitcoinSilver (BTCS)
Built with Flutter for Android & iOS

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Features

• BIP39 Seed Phrase Support: Create or restore wallets using 12 or 24-word recovery phrases.
• Cross-Platform Compatibility: Uses standard derivation path m/44'/0'/0'/0/0 (same as Web Wallet 2.2).
• Advanced Recovery: Support for raw private key (WIF) recovery and generation.
• Local Transaction Signing (No Node Key Exposure): Transactions are built and signed in-app using local keys, then broadcast as raw hex.
• Seed + WIF Wallet Modes: Users can create/use both mnemonic-based and WIF-based wallets.
• Advanced Send / Coin Control: Select specific confirmed UTXOs, paginate inputs, estimate fees, and preview net send amount.
• Send and Receive: Seamless BTCS transfers for both legacy and SegWit destination types.
• BTCS Address Compatibility: Supports BTCS Bech32 (bs1...) and legacy Base58 address handling in signer and send flow.
• Address Validation Improvements: Debounced validation, scanner/address-book parity, and resilient fallback validation for BTCS RPC edge cases.
• QR Code Scanning: Reads BIP21 payment requests (bitcoinsilver:<address>?amount=..&message=..) and fills in both the address and the amount.
• Payment Requests: Request an amount with a QR code or a shared message that includes a link for the web wallet. Requests can also be pasted into the Send screen.
• Address Book: Labelled contacts with .btcs import/export, compatible with the web wallet.
• Transaction Tracking: Real-time history with smart confirmation tracking and pending-state management.
• Smart Pending Handling: Tracks local pending spends, avoids double-spend UTXO reuse, and keeps balances accurate during mempool transitions.
• Biometric Security: Protect your wallet and recovery phrase with fingerprint or face recognition.
• Secure Storage: Sensitive keys and mnemonics are stored in encrypted secure storage.

Latest Updates

Version 6.4.1 (details in CHANGELOG.md), together with web wallet 3.1.1:

• Faster start: the app no longer waits for the servers before showing the wallet; history and balance load in the background.
• Returning to the app keeps the transaction list on screen while it refreshes (no more brief "No Transactions Yet").
• Fingerprint lock covers every screen when returning to the app, including Send, Receive and Settings.
• Payment requests: the name in a request is marked as not verified, a warning appears when a request borrows a saved contact's name, and hidden characters are removed.
• Address book: each contact has a Send button.

Version 6.4, released together with web wallet 3.1:

• Scanning a payment request now fills in the amount, not only the address, and shows the request's note.
• Payment requests shared from the Receive screen include a web wallet link.
• Fixed: exporting the address book over an older file could leave part of the old file behind, making it impossible to import.

Earlier:

• Qr code scanner added to Address Book

• Added "Subtract Fee from amount" toggle in send view

• Chat has been removed due to a recent Google Play policy change/update

• Refined Send fee UX with a clearer fee source selector (Manual vs Auto (Node Fee)) and active-state highlighting.

• Simplified estimated fee card layout with clearer grouping: estimated fee, fee source, fee rate, and net send after fee (advanced input-selected mode).

• Improved simple mode fee estimation to be amount-aware using confirmed UTXOs, producing more realistic estimates than a fixed baseline example.

• Kept advanced mode fee behavior input-aware from selected UTXOs (coin control), so detailed estimates remain tied to selected inputs.

• Upgraded to Flutter 3.47.2 • channel stable

• Upgraded to Android Gradle Plugin (AGP) 9.7.1

• Upgraded to Kotlin 2.4.10

• Migration Flow Hardening:

  • Added explicit migration warning + acknowledgment step before migration starts.
  • Added funded-wallet pre-check for smart fee availability and blocks migration when node fee estimation is unavailable.
  • Added pending-transaction guard: migration is delayed while unconfirmed/pending transactions exist.
  • Added secure-storage preflight and fail-closed behavior before irreversible sweep operations.
  • Added migration integrity checks for migrated private key/address consistency before success handoff.
  • Added detailed failure dialog path so users get clear migration error reasons.
  • Added stage-based migration progress dialogs for both pre-send preparation and send/finalize phases.
  • Added migration interruption handling with explicit user guidance when app context changes mid-flow.
  • Added migration cancellation feedback dialog so exits are not silent.
  • Added one-tap "Copy All Backup Data" action (formatted address + seed + WIF + optional sweep amount).
  • Enforced post-success backup confirmation dialog before final completion.
  • Updated empty-wallet migration success wording to avoid claiming a transaction was sent.

• Fee Estimation Hardening:

  • Handles estimatesmartfee failures explicitly (RPC errors, missing feerate, and feerate: -1 / no estimate).
  • Adds send-time manual fee entry fallback when estimation is unavailable.
  • Shows fee estimation status on Send screen with loading state and warning indicator.
  • Blocks signing/broadcast until a valid fee rate is provided (estimated or manual).
  • Fee-bump retry dialog only runs for transactions that started from estimator-provided fee rates.

• Manual Fee UX Improvements:

  • Unit toggle for sat/vB and BTCS/kvB with conversion.
  • Network-condition presets tuned to current conditions:
    • Low: 0.00000226 BTCS/kvB
    • High: 0.0004 BTCS/kvB

• Resume/Background Reliability:

  • Improved silent transaction refresh behavior so latest transactions are reloaded after app resume/background transitions.
  • Added shared wallet sync coalescing for timer/resume/manual refresh to avoid overlapping sync races.
  • Reduced startup blocking when RPC is unavailable while preserving RPC warning visibility.

• Send Preview Consistency:

  • Transaction preview now updates live on amount edits.
  • Auto input-selection mode now shows computed expected change instead of "Auto".

• Performance improvements and dependency updates.

Quick Start

# Install dependencies
flutter pub get

# Run in development (uses public RPC)
flutter run

# Build APK
flutter build apk

# Build with custom RPC
flutter build apk --release --obfuscate --split-debug-info=build/app/outputs/symbols --dart-define-from-file=dart_defines.json

Configuration

The wallet connects to the public RPC proxy at https://bitcoinsilver.eu/btcs-rpc by default (no authentication required).

For custom RPC node, create dart_defines.json:

{
  "RPC_URL": "http://your-rpc:port",
  "RPC_USER": "your_user",
  "RPC_PASSWORD": "your_password"
}

Build for Production

# Android APK
flutter build apk --release --dart-define-from-file=dart_defines.json

# Android App Bundle (Play Store)
# --extra-gen-snapshot-options=--strip removes the DWARF debug info that newer
# Flutter otherwise leaves in the native library (it would partly undo
# --obfuscate). `flutter build` has no --strip flag of its own. The symbols
# needed to read crash reports are still written to --split-debug-info.
flutter build appbundle --release --obfuscate \
  --extra-gen-snapshot-options=--strip \
  --split-debug-info=build/app/outputs/symbols \
  --dart-define-from-file=dart_defines.json

# iOS
flutter build ios --release --dart-define-from-file=dart_defines.json

Output locations:

• APK: build/app/outputs/flutter-apk/app-release.apk
• AAB: build/app/outputs/bundle/release/app-release.aab
• Debug symbols (upload to Play Console for readable crash reports): build/app/outputs/symbols

With --extra-gen-snapshot-options=--strip, Flutter (3.47) ends the bundle build with "Release app bundle failed to strip debug symbols from native libraries" and exit code 1, although the .aab is complete, signed and stripped. Its check expects a debug-symbol entry for libapp.so, which --strip intentionally leaves empty. Check that build/app/outputs/bundle/release/app-release.aab has a fresh timestamp before uploading.

Before each Play Store upload, raise versionCode in android/app/build.gradle.kts (the Play Console refuses a code it has seen, including internal test uploads).

iOS Release (GitHub Actions)

The workflow .github/workflows/ios_release.yml ("iOS Release Build") builds a signed iOS app on a GitHub macOS runner and uploads it to TestFlight. It never runs on a push: it only starts when you start it. Commits that should not be picked up by any future automatic workflow can still carry [skip ci] in the message.

Before starting it

1. Commit and push everything that should be in the build; the workflow builds the main branch as it is on GitHub.
2. Raise the version in pubspec.yaml (version: 6.4.1+5). iOS uses it directly: 6.4.1 is the version users see, and the number after + is the build number, which must be higher than any build already uploaded to App Store Connect, including TestFlight uploads.
3. Check that the signing files have not expired: the Apple Distribution certificate (yearly) and the provisioning profile (yearly). Renewing either means updating its repository secret (below).

Starting it

On GitHub: open the repository → Actions → iOS Release Build → Run workflow → branch main → Run workflow.

Or from a terminal with the GitHub CLI:

gh workflow run ios_release.yml -R bitcoin-silver/wallet --ref main
gh run watch -R bitcoin-silver/wallet        # follow it (choose the new run)
gh run list -R bitcoin-silver/wallet --workflow ios_release.yml -L 5

A run takes roughly 8 to 10 minutes. When it succeeds, the build appears in App Store Connect → TestFlight after Apple's processing (usually 10 to 30 minutes). The .ipa is also kept as the run's ios-ipa artifact, even when the TestFlight upload fails.

What it uses

• Flutter 3.47.5, pinned in the workflow to the version used for local and Android builds. When you upgrade Flutter locally, raise flutter-version in the workflow too.
• Bundle ID top.bitcoinsilver.bitcoinsilverWallet, manual signing with the "Apple Distribution" certificate.
• Repository secrets (Settings → Secrets and variables → Actions):

Secret	Used for
IOS_DIST_CERT_P12_BASE64, IOS_DIST_CERT_PASSWORD	Apple Distribution certificate (.p12, base64) and its password
IOS_PROVISION_PROFILE_BASE64	App Store provisioning profile (.mobileprovision, base64)
KEYCHAIN_PASSWORD	Any password for the temporary keychain on the runner
APPSTORE_TEAM_ID	Apple developer team ID
APPSTORE_API_KEY_ID, APPSTORE_API_ISSUER_ID, APPSTORE_API_PRIVATE_KEY	App Store Connect API key used to upload to TestFlight
RPC_URL, NOTIFICATION_API_KEY, LIVECOINWATCH_API_KEY	Written into dart_defines.json, like the local dart_defines.json
RPC_USER, RPC_PASSWORD	Optional; not needed for the default public RPC proxy

To store a file as a base64 secret: base64 -i file.p12 | pbcopy on macOS, or base64 -w0 file.p12 on Linux, then paste the output as the secret's value.

If it fails

Open the run on GitHub and look at the first red step:

• Import signing certificate…: a certificate or profile secret is wrong or expired.
• Build signed IPA: a code or dependency problem; try flutter build ios --release locally on a Mac with the same Flutter version.
• Upload to TestFlight: usually a build number that was already used (raise the number after + in pubspec.yaml) or an App Store Connect API key issue.

Security

• Private keys stored in encrypted secure storage (Keychain/KeyStore)
• Optional biometric authentication
• RPC credentials injected at build time, never hardcoded
• No personal data collected

Never commit dart_defines.json or .env to version control.

Migration Safety Checklist

Use this quick checklist after migration-related changes:

• Warning + Consent: Migration starts only after user acknowledgment dialog is accepted.
• Pending Guard: Migration is blocked while pending/unconfirmed transactions exist.
• Fee Guard: Funded migration is blocked when smart fee estimation is unavailable.
• Storage Guard: Secure storage preflight succeeds before sweep/save steps.
• Integrity Guard: On success, migrated private key and derived address are validated.
• Backup Gate: Success requires user backup confirmation dialog completion.
• Backup Copy Action: Users can copy all migration backup data in one formatted payload.
• Interruption UX: Context-loss/interruption is surfaced with a retry-in-one-go notice.
• Failure UX: Any failure path shows a clear reason dialog and keeps old wallet active.
• Resume Sync: After app resume/background transitions, latest transactions reload correctly.

Suggested manual smoke test sequence:

1. Empty wallet migration (12-word and 24-word).
2. Funded wallet migration with small amount.
3. Funded wallet migration with larger/fragmented UTXOs.
4. Pending transaction scenario (verify migration is delayed).
5. Smart fee unavailable scenario (verify migration is blocked with explanation).

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/my-feature)
3. Commit your changes (git commit -m 'Add my feature')
4. Push to the branch (git push origin feature/my-feature)
5. Open a Pull Request

For bugs or feature requests, please open an issue.

Current Google Play version: 6.3

License

MIT