How to Build a Cross-Platform Algorand Wallet Using C#

Introduction

This guide explores developing a cross-platform Algorand wallet with GUI functionality using C#. While wallet development involves extensive code, we focus on key technologies like Algorand network integration, secure password storage, and Avalonia-based UI design.

Prerequisites: Basic C# knowledge and familiarity with Algorand concepts.

Development Environment

• OS: Windows 10
• IDE: Visual Studio 2019

• Dependencies:

  • dotnet-algorand-sdk (v0.1.2.6) for Algorand connectivity
  • Avalonia for cross-platform GUI
  • BouncyCastle for cryptographic operations

Install dependencies via NuGet. Note: dotnet-algorand-sdk is listed as "Algorand" on NuGet.

Wallet Features

1. Connect to Algorand Network
2. Create/Import Wallets
3. Send/Receive ALGO

4. ASA (Algorand Standard Asset) Management

   • Create, send, and receive ASAs
5. Transaction History

👉 Explore complete code on GitHub

Algorand Connectivity

Connecting to Algorand

Use dotnet-algorand-sdk to connect via:

• Independent Node: Requires IP + algod token
• PureStake: API address + key

string ALGOD_API_ADDR = "API_ADDRESS";  
string ALGOD_API_TOKEN = "API_KEY";  
AlgodApi algodApiInstance = new AlgodApi(ALGOD_API_ADDR, ALGOD_API_TOKEN);  

try {  
    Supply supply = algodApiInstance.GetSupply();  
    Console.WriteLine($"Total Supply: {supply.TotalMoney}");  
} catch (ApiException e) {  
    Console.WriteLine($"Error: {e.Message}");  
}  

Transaction Flow

1. Sign Transactions: Use Account.SignTransaction.
2. Send ALGO:

ulong amount = 100000; // 0.1 ALGO  
Transaction tx = new Transaction(src.Address, destAddr, amount, params);  
SignedTransaction signedTx = src.SignTransaction(tx);  
TransactionID id = algodApiInstance.RawTransaction(encodedMsg);  

ASA Operations

ulong assetAmount = 10;  
tx = Utils.GetTransferAssetTransaction(sender, receiver, assetID, assetAmount, params);  
signedTx = account.SignTransaction(tx);  
Utils.SubmitTransaction(algodApiInstance, signedTx);  

GUI with Avalonia

Why Avalonia?

• Cross-platform XAML framework compatible with .NET Core.
• Similar to WPF, making it easy for WPF developers.

Key Steps:

1. Create Project: Use Avalonia templates in Visual Studio.
2. Design UI: Example AXAML for login screen:

<Window xmlns="https://github.com/avaloniaui">  
    <StackPanel>  
        <TextBox Name="PasswordBox" Watermark="Enter Password"/>  
        <Button Name="SubmitBtn" Content="OK"/>  
    </StackPanel>  
</Window>  

3. Event Handling:

this.FindControl<Button>("SubmitBtn").Click += (sender, e) => {  
    var password = this.FindControl<TextBox>("PasswordBox").Text;  
    // Handle auth  
};  

Secure Key Storage

Encryption Workflow:

1. Generate 48-byte hash using SCrypt (password + salt).
2. Split hash: First 16 bytes for password validation, last 32 for AES-GCM encryption.
3. Encrypt master key with AES-GCM and nonce.

byte[] salt = CryptoUtils.GenerateRandomSalt();  
byte[] scryptedKey = CryptoUtils.GenerateHash(salt, password);  
byte[] masterKey = CryptoUtils.GetMasterKey(scryptedKey);  
byte[] encryptedKey = CryptoUtils.EncryptAesGcm(masterKey, nonce, privateKey);  

Decryption:

byte[] decryptedKey = CryptoUtils.DecryptAesGcm(masterKey, nonce, cipherText, tag);  

FAQ

1. Why use Avalonia over WPF?

Avalonia supports macOS/Linux, while WPF is Windows-only.

2. Is AES-GCM secure for key storage?

Yes, it provides authenticated encryption, ensuring both confidentiality and integrity.

3. Can I migrate wallet files between apps?

Only if nonce values are shared; otherwise, use app-specific nonces.

👉 Learn more about secure key management

Conclusion

This guide covered Algorand SDK integration, Avalonia UI design, and secure key storage. For deeper dives, explore the full project code. Happy coding!