Full Keystone HW Wallet Support #355

n13 · 2026-01-08T01:02:13Z

Overview

Improvements to multiple account handling (actually works now)
UX for add hardware wallet - feature flag protected
UX for multiple mnemonics in settings
UX for add / import additional wallets
Send overlay for scanning QR codes in the case of hardware wallet
Testing facilities to test partially signed transactions
Added UR scanning library in Rust - UR is a standard for moving QR codes

Demo

Caveats

The send overlay is super complicated now, follow up PR will refactor this to make it smaller and factor our things into a hardware wallet service.

Will be fixed here:
#356

this helps the hardware wallet. there may be another way to do this but for now dummy signature works well.

lol

upgrade dependencies to pointy castle 4.0.0 to be compatible with the latest polkadart version. also upgrade human checksum dart to v1.1.0 tag so we are compatible with pointycastle.

The HW wallet will need to blake2 the output before signing.

These are useful as a reference implementation

removed uneeded file, fix doc comment, formatting

Alles was nicht erlaubt ist ist verboten!

no need for hex encoding since UR is CBOR encoded

add known value test

mobile-app/lib/features/components/button.dart

mobile-app/lib/features/main/screens/account_settings_screen.dart

mobile-app/lib/features/main/screens/accounts_screen.dart

dewabisma · 2026-01-08T05:32:47Z

mobile-app/lib/features/main/screens/accounts_screen.dart

+      Item(value: _WalletMoreAction.importWallet, label: 'Import wallet'),
+    ];
+
+    if (FeatureFlags.isFeatureEnabled('keystone_hardware_wallet')) {


Let's make the flag an enum

I just wanted to fit in the system. As I am concerned we could just have some booleans. Not sure why we have this fancy system with strings.

Not related to this PR - should be follow up PR refactor.

Okay, we can do either way, using string just ain't safe enough

mobile-app/lib/features/main/screens/accounts_screen.dart

mobile-app/lib/features/main/screens/send/qr_scanner_screen.dart

dewabisma · 2026-01-08T05:40:50Z

quantus_sdk/lib/src/constants/app_constants.dart

@@ -1,5 +1,6 @@
 class AppConstants {
  static const globalDebug = false;
+  static const debugHardwareWallet = false;


Is this used at all?

Yes. Not sure we should leave this debug code in there now that it works. Hmm...

Moved this to the end of the file and added a comment since this is quite intricate.

dewabisma · 2026-01-08T06:23:05Z

GEMINI PRO 3 REVIEW

The branch n13/hardware_wallet_support implements comprehensive support for Keystone hardware wallets using an air-gapped QR code flow. The changes span the Flutter mobile app, the Dart SDK, and the Rust bridge.

Summary of Changes

Mobile App UI (mobile-app/lib/features/main/screens/...):
- New Screens: AddHardwareAccountScreen for importing hardware accounts via QR code.
- Updated Flows: AccountsScreen now handles multiple wallets and grouping by wallet index. Added SelectWalletForRecoveryPhraseScreen to handle multiple wallets.
- Signing Flow: SendProgressOverlay now supports a hardware signing state (hardwareSign, hardwareScan). It displays the unsigned transaction as a QR code (UR encoded) and scans the signature back.
- Settings: Added "Disconnect Wallet" functionality in AccountSettingsScreen.
SDK Core (quantus_sdk/lib/src/...):
- QuantusPayloadParser: New class to parse SCALE-encoded transaction payloads into human-readable details (toAddress, amount, isReversible), essential for the hardware wallet display.
- QuantusSigningPayload: Extends SigningPayload to ensure the raw payload is returned (not hashed) for hardware signing, matching the polkadart update.
- UR Support: Added ur.rs (Rust) and corresponding Dart bindings to handle Uniform Resources (UR) encoding/decoding for QR codes.
Rust Bridge (quantus_sdk/rust/...):
- Exposed crypto constants (public_key_bytes, etc.).
- Added ur.rs wrapping quantus-ur for efficient QR encoding.

Code Review

Positives:

Architecture: Logic for parsing payloads and handling UR encoding is cleanly separated in the SDK and Rust layer.
Safety: The feature is correctly flagged behind keystone_hardware_wallet in feature_flags.dart, ensuring it doesn't leak into production before readiness.
Testing: Added unit tests for the Rust UR implementation (ur.rs) and payload parser.

Issues / Suggestions:

Unused Import:
In mobile-app/lib/features/main/screens/send/qr_scanner_screen.dart, line 2:
```
import 'package:quantus_sdk/quantus_sdk.dart' as crypto;
```
This alias crypto appears to be unused, as the file also imports the package without an alias.
Debug Code:
In mobile-app/lib/features/main/screens/add_hardware_account_screen.dart, _fillDebugAddress contains a hardcoded address. It is correctly guarded by if (kDebugMode) in the build method, so this is acceptable for development but good to be aware of.
Code Consistency:
In SendProgressOverlay.dart, the check if (account.accountType == AccountType.keystone || AppConstants.debugHardwareWallet) correctly redirects the flow. The debug simulation button is also correctly guarded by AppConstants.debugHardwareWallet.

Recommendation

The implementation looks solid. I recommend removing the unused import in qr_scanner_screen.dart before merging.

The branch n13/hardware_wallet_support implements hardware wallet (Keystone) support with a new QR-code-based signing flow.

Key Changes

Mobile App:
- New Screens: AddHardwareAccountScreen for importing wallets via QR and SendProgressOverlay updates for the "sign and scan" flow.
- Multi-wallet Support: AccountsScreen now groups accounts by wallet index.
- Feature Flag: Protected by keystone_hardware_wallet.
SDK:
- Payload Parsing: QuantusPayloadParser decodes SCALE payloads for display on the hardware device.
- UR Support: New Rust bridge (ur.rs) for Uniform Resources QR encoding/decoding.

Review Actions

I found one minor issue and fixed it:

Removed unused import: import 'package:quantus_sdk/quantus_sdk.dart' as crypto; in qr_scanner_screen.dart was redundant.

The rest of the code looks well-structured, with clear separation between UI, SDK logic, and Rust crypto primitives. The feature is safely flagged for incremental rollout.

dewabisma

I have manually reviewed it and also use gemini pro 3 to review.

dewabisma · 2026-01-08T09:19:51Z

mobile-app/lib/features/main/screens/accounts_screen.dart

  }

+  int getSelectedWalletIndex(List<Account> accounts) {
+    final selectedWallet = _selectedWalletIndex ?? (accounts.isNotEmpty ? accounts.first.walletIndex : 0);


I mean can we not use ternary? We can do if else instead.

if (_selectedWalletIndex != null) { return _selectedWalletIndex } else if (accounts.isNotEmpty) { return accounts.first.walletIndex } else { return 0 }

whats all this hate for ternary?

I mean to me this if statement is less clear than the original... I have to think about it more

The original is simply this

if it's defined, return it

if it's not defined, return some sort of reasonable default...

if there are wallets, return the first wallet index

if not, return 0 - but this case never happens here, thats just there to make this function return an int thats' not optional.

dewabisma

LGTM! Just have one non blocking request for change

n13 added 30 commits December 14, 2025 16:53

add wallet index

0668eb9

add account type

aa207a8

UX for adding hardware

dc021f0

melos format

bd9f22c

scan QR added, debug fill button added

ec5dd30

do fee estimate without signing the transaction

2a24647

this helps the hardware wallet. there may be another way to do this but for now dummy signature works well.

hardware wallet simulator

dcc4ee2

debug and management tools

198f970

add remove wallets for hw wallet added

9a985ff

remove stray wallet selector added by AI

a44a999

lol

debug hw is false by default

07a5e58

formatting

ee4a7c8

linter fixes

7a7e503

upgrade dependencies to pointy castle 4.0.0 to be compatible with the latest polkadart version. also upgrade human checksum dart to v1.1.0 tag so we are compatible with pointycastle.

simplify UnsignedTransactionData

d06a784

mark fields final

9379399

minor bugfix - the entire copy area is clickable

7f6b702

packing the entire keystone UX into the send overlay!

ca6e811

remove debug code from scanner overlay

3b5e4ac

raw signing payload for the HW wallet

e1be15e

The HW wallet will need to blake2 the output before signing.

add comment and remove printout

f1dfd22

Add payload parser, parser tests

09b3a50

These are useful as a reference implementation

fix payload parser to correctly return milliseconds for timestamps

0754122

remove print

16b7f30

test reversible transfer parsing with real world values

cb61a11

fix unused import

d2ac80c

linter fixes

97a1a18

removed uneeded file, fix doc comment, formatting

adding rust based payload parser

accddc7

cast 32 to 64 instead of vice versa

08d18e5

rust parser throwing errors for anything not allowed

b50cd31

Alles was nicht erlaubt ist ist verboten!

recovery screen shows phrases for all non hardware wallets

5d41dd0

n13 added 8 commits December 19, 2025 20:29

adding random segment test and comment on UR in general

796c9bd

use byte encode / decode

0024e24

no need for hex encoding since UR is CBOR encoded

parsing signature and pubkey confirmed

147b941

add known value test

Merge branch 'main' into n13/4-scan-ur-animated-qr-codes

86d0a5a

hardware wallet feature flag

aefec85

recover widget tests and mocks

7aa632f

melos format

6c1ff47

add cursor to git ignore

4ef2721

dewabisma reviewed Jan 8, 2026

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n13 added 2 commits January 8, 2026 14:16

remove ai comment

2b7c2ab

move selected wallet index into its own method

b8c4fd3

delete commented code

db71514

dewabisma requested changes Jan 8, 2026

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n13 added 2 commits January 8, 2026 14:24

delete duplicate import

cdd3aa2

move debug hw flag

d8274ac

n13 requested a review from dewabisma January 8, 2026 06:28

add disabled to danger outline button, format

76e056c

dewabisma reviewed Jan 8, 2026

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dewabisma approved these changes Jan 8, 2026

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Merge branch 'main' into n13/hardware_wallet_support

fed6486

n13 merged commit af9dedd into main Jan 8, 2026
1 check passed

dewabisma deleted the n13/hardware_wallet_support branch January 9, 2026 04:13

Full Keystone HW Wallet Support #355

Full Keystone HW Wallet Support #355

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n13 commented Jan 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Overview

Demo

Caveats

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dewabisma commented Jan 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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GEMINI PRO 3 REVIEW

Summary of Changes

Code Review

Recommendation

Key Changes

Review Actions

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n13 commented Jan 8, 2026 •

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