secure storage windows by mistic0xb · Pull Request #672 · block-core/angor

mistic0xb · 2026-02-24T11:51:46Z

Secure Wallet Storage Implementation (Windows)

Overview

This PR implements passwordless wallet encryption using Windows DPAPI (Data Protection API) and AES-256-GCM authenticated encryption. Users no longer need to enter or remember encryption passwords when creating or importing wallets.

How It Works

Two-Layer Encryption Architecture

The implementation uses an envelope encryption pattern with two distinct layers:

OS-Level Protection (DPAPI)
- A unique 256-bit master key is generated per wallet
- The master key is encrypted by Windows DPAPI bound to the current user account
- DPAPI-encrypted keys are stored in %AppData%\Angor\secure\{walletId}.key
- Keys can only be decrypted by the same Windows user on the same machine
Wallet Data Encryption (AES-GCM)
- The master key encrypts wallet seed words and metadata using AES-256-GCM
- GCM mode provides authenticated encryption (AEAD) — detects tampering automatically
- Encrypted wallet data is stored in the existing LiteDB database

Wallet Creation Flow

User enters seed words -> no password prompt
System generates a random 256-bit master key
Master key is encrypted with DPAPI -> saved to %AppData%\Angor\secure\{walletId}.key
Master key encrypts wallet data with AES-GCM
Master key bytes are cleared from memory

Wallet Access Flow

Application loads encrypted wallet
System reads DPAPI-encrypted key file
DPAPI decrypts the master key silently (no user interaction)
Master key decrypts wallet data with AES-GCM
Seed words returned to application

Security Properties

What's Protected:

Master keys are bound to Windows user + machine (DPAPI CurrentUser scope)
Additional entropy per wallet prevents key reuse attacks
AES-GCM authentication tags detect any tampering with encrypted wallet data
Sensitive data cleared from memory after use
Key files marked as hidden system files

Platform Support

Current: Windows only (DPAPI)
Future: Cross-platform support planned via platform-specific secure storage:

macOS: Keychain
Linux
Android: Android Keystore
iOS: iOS Keychain

The AES-GCM encryption layer remains identical across platforms — only the master key storage mechanism changes.

Breaking Changes

IWalletFactory.CreateWallet signature changed — removed encryptionKey parameter
UI wizard flows updated — removed encryption password step
Existing wallets encrypted with user passwords are not migrated automatically — users must re-import from seed words

Why Two Layers?

This approach separates concerns:

DPAPI layer: Where the secret lives (OS-managed, platform-specific)
AES-GCM layer: What it protects (portable, platform-independent)

Benefits:

Easy to swap DPAPI for Apple-Keychain/Android-Keystore/Linux when going cross-platform

Testing

Manual testing performed on Windows 11. Verify:

Wallet creation completes without password prompt
Wallet loads on app restart without password
.key files created in %AppData%\Angor\secure\
Multiple wallets each get unique keys
Import wallet flow works without password

added secure storage (windows) secure-storage for windows woking

dangershony · 2026-02-24T17:57:35Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Application/IWalletAppService.cs

    Task<Result<Address>> GetNextReceiveAddress(WalletId id);
-    Task<Result<WalletId>> CreateWallet(string name, string seedwords, Maybe<string> passphrase, string encryptionKey, BitcoinNetwork network);
-    Task<Result<WalletId>> CreateWallet(string name, string encryptionKey, BitcoinNetwork network);
+    Task<Result<WalletId>> CreateWallet(string name, string seedwords, Maybe<string> passphrase, BitcoinNetwork network);


I wonder if we should leave the existing way as well?

I agree, this should be an overload.

dangershony · 2026-02-24T17:58:48Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Impl/DefaultSensitiveWalletDataProvider.cs

-            .Bind(wallet => walletEncryption.Decrypt(wallet, "DEFAULT")) // Try to decrypt the wallet with the default encryption key ("DEFAULT")
-            .Map(data => (data.SeedWords, Maybe<string>.None))  // On success, return its seedwords (assume no passphrase)
-            .Compensate(_ => provider.RequestSensitiveData(walletId));  // On failure, delegate to the flow to the inner provider. This is, the default encryption key failed to decrypt the wallet didn't work.
+                          .Bind(wallets => wallets.TryFirst().ToResult("Wallet not found"))


has something changed here? or only removed comments?

dangershony · 2026-02-24T18:03:21Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Impl/DpapiSecureStorage.cs

+                // Set file attributes to hidden and system for additional security
+                File.SetAttributes(keyFilePath, FileAttributes.ReadOnly | FileAttributes.System);
+
+                Console.WriteLine($"[SecureStorage] Master key stored for wallet: {walletId}");


we have loggers so use that instead of console

dangershony · 2026-02-24T18:05:13Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Impl/DpapiSecureStorage.cs

+    /// Stores a master encryption key securely using Windows DPAPI.
+    /// If no key is provided, generates a new one.
+    public async Task<Result<string>> StoreMasterKeyAsync(
+        string walletId,


the masterkey is per wallet? I am not sure we need that level of separation we can just use one master key for all wallets I suppose?

I guess it is not such a big deal but it doeas put a dependency on the database, we must know the wallet id in order to decrypt a wallet.

dangershony · 2026-02-24T18:12:18Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Impl/WalletFactory.cs

+        if (encryptResult.IsFailure)
+            return Result.Failure<Domain.Wallet>(encryptResult.Error);
+
+        // remove existing entry with same ID before saving — safe on retry


remove existing entry with same ID before saving — safe on retry

what is this comment exactly not sure it is even correct?

dangershony · 2026-02-24T18:13:47Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Impl/WalletFactory.cs

-
-    private async Task<Result> SaveEncryptedWalletToStoreAsync(string name, string encryptionKey, WalletData walletData,
-        WalletId walletId)
+    private async Task<Result> SaveEncryptedWalletToStoreAsync(string name, string encryptionKey, WalletData walletData, WalletId walletId)


here we have an encryptionKey?

dangershony · 2026-02-24T18:16:38Z

src/Angor/Avalonia/Angor.Sdk/Wallet/WalletContextServices.cs

        services.AddSingleton<ITransactionHistory, TransactionHistory>();
        services.TryAddSingleton<IWalletAccountBalanceService, WalletAccountBalanceService>();
        services.AddHttpClient();
+        services.AddSingleton<ISecureStorage, DpapiSecureStorage>();


what about none windows devices?

DavidGershony · 2026-02-25T15:22:12Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Impl/DpapiSecureStorage.cs

+
+    private static string GenerateMasterKey()
+    {
+        using var rng = RandomNumberGenerator.Create();


I think you need to use the cryptographically secure random number generator here

DavidGershony · 2026-02-25T15:24:22Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Impl/WalletAppService.cs

+    public async Task<Result<WalletId>> CreateWallet(string name, string seedWords, Maybe<string> passphrase , BitcoinNetwork network)
    {
-        var wallet = await walletFactory.CreateWallet(name ?? SingleWalletName, seedWords, passphrase, encryptionKey, network);
+        var wallet = await walletFactory.CreateWallet(name ?? SingleWalletName, seedWords, passphrase, network);


If you remove this we will only support Windows. you need to have a check if we can create without a password perhaps.

DavidGershony · 2026-02-25T15:28:55Z

src/Angor/Avalonia/Angor.Sdk/Wallet/Infrastructure/Interfaces/IWalletImporter.cs

 public interface IWalletFactory
 {
-    Task<Result<Domain.Wallet>> CreateWallet(string name, string seedwords, Maybe<string> passphrase, string encryptionKey, BitcoinNetwork network);
+    Task<Result<Domain.Wallet>> CreateWallet(string name, string seedwords, Maybe<string> passphrase, BitcoinNetwork network);


We should have both options here.

DavidGershony · 2026-02-25T15:29:33Z

src/Angor/Avalonia/Angor.Sdk/Wallet/WalletContextServices.cs

        services.AddSingleton<ITransactionHistory, TransactionHistory>();
        services.TryAddSingleton<IWalletAccountBalanceService, WalletAccountBalanceService>();
        services.AddHttpClient();
+        services.AddSingleton<ISecureStorage, DpapiSecureStorage>();


Should have a way to check the OS so we know it works as well

DavidGershony · 2026-02-25T15:31:01Z

src/Angor/Avalonia/AngorApp/UI/Shared/Services/WalletContext.cs

    public Task<Result<IWallet>> GetOrCreate()
    {
-        return walletAppService.CreateWallet("<default>",  GetUniqueId(), bitcoinNetwork())
+        return walletAppService.CreateWallet("<default>", bitcoinNetwork())


Delete the method GetUniqueId as well

DavidGershony

Needs some changes

secure storage windows

dfccfd6

added secure storage (windows) secure-storage for windows woking

mistic0xb requested review from DavidGershony and SuperJMN February 24, 2026 11:51

dangershony reviewed Feb 24, 2026

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DavidGershony reviewed Feb 25, 2026

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DavidGershony requested changes Feb 25, 2026

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mistic0xb commented Feb 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Secure Wallet Storage Implementation (Windows)

Overview

How It Works

Two-Layer Encryption Architecture

Wallet Creation Flow

Wallet Access Flow

Security Properties

Platform Support

Breaking Changes

Why Two Layers?

Testing

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mistic0xb commented Feb 24, 2026 •

edited

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