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

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Creating a secure, user-friendly cryptocurrency wallet is one of the most practical and empowering applications in blockchain development. In this comprehensive guide, we’ll walk through how to build a cross-platform Algorand wallet using C#, combining modern .NET capabilities with robust cryptographic security and intuitive UI design.

Whether you're a developer exploring decentralized finance (DeFi) or building tools for the Algorand ecosystem, this tutorial equips you with the foundational knowledge to create a fully functional desktop wallet that supports ALGO transfers, ASA (Algorand Standard Asset) management, and secure key storage.

Development Environment & Core Dependencies

To ensure cross-platform compatibility and maintainability, we use industry-standard tools and libraries within the .NET ecosystem:

💡 Note: The Algorand SDK on NuGet is not always up-to-date. Use version 0.1.2.6 for stability and full feature support.

These components allow us to write once and deploy across platforms—perfect for desktop wallet applications.

👉 Discover powerful crypto development tools to enhance your Algorand projects.

Core Features of the Algorand Wallet

This wallet implementation includes essential functionalities required by any modern blockchain wallet:

The complete source code is available in the open-source repository RileyGe/algo-wallet, though this article focuses on core concepts rather than full code replication.

Connecting to the Algorand Network

Interacting with Algorand starts with establishing a connection to an algod node. You can connect either through a local node or a third-party service like PureStake.

Initialize Algod Client

string ALGOD_API_ADDR = "https://testnet-algorand.api.purestake.io/ps2";
string ALGOD_API_TOKEN = "your-api-key";
AlgodApi algodApiInstance = new AlgodApi(ALGOD_API_ADDR, ALGOD_API_TOKEN);

try 
{
    Supply supply = algodApiInstance.GetSupply();
    Console.WriteLine("Total Algorand Supply: " + supply.TotalMoney);
    Console.WriteLine("Online Algorand Supply: " + supply.OnlineMoney);
}
catch (ApiException e)
{
    Console.WriteLine("Exception when calling algod#getSupply: " + e.Message);
}

This single block establishes connectivity and retrieves network-wide data such as total supply—validating that your SDK integration works.

Signing Transactions: The Backbone of Blockchain Security

Every operation on the Algorand blockchain must be cryptographically signed to prove ownership and intent.

Why Signing Matters

As Vitalik Buterin once described, blockchains are like a "world computer"—decentralized and always on. To prevent spam and unauthorized actions, every transaction must:

  1. Be signed by the sender’s private key
  2. Include a fee (in microAlgos) to enter the ledger

Signing ensures accountability and security without central oversight.

Common Signing Methods

In the .NET SDK:

These methods return a SignedTransaction, which is then encoded and broadcast to the network.

Executing ALGO Transfers

Transferring ALGO involves constructing a transaction, signing it, and submitting it to the network.

Step-by-Step Transfer Example

ulong amount = 100000; // 0.1 ALGO in microAlgos
ulong lastRound = firstRound + 1000;
string mnemonic = "typical permit hurdle hat song detail cattle merge oxygen crowd arctic cargo smooth fly rice vacuum lounge yard frown predict west wife latin absent cup";
Account src = new Account(mnemonic);
string DEST_ADDR = "KV2XGKMXGYJ6PWYQA5374BYIQBL3ONRMSIARPCFCJEAMAHQEVYPB7PL3KU";

Transaction tx = new Transaction(
    src.Address,
    new Address(DEST_ADDR),
    amount,
    firstRound,
    lastRound,
    genesisID,
    genesisHash
);

SignedTransaction signedTx = src.SignTransactionWithFeePerByte(tx, feePerByte);

try 
{
    var encodedMsg = Algorand.Encoder.EncodeToMsgPack(signedTx);
    TransactionID id = algodApiInstance.RawTransaction(encodedMsg);
    Console.WriteLine("Successfully sent tx with id: " + id.TxId);
}
catch (ApiException e)
{
    Console.WriteLine("Exception when calling algod#rawTransaction: " + e.Message);
}
✅ Pro Tip: Use Utils.SubmitTransaction(algodApiInstance, signedTx) for one-step encoding and submission.

Managing Algorand Standard Assets (ASA)

ASAs extend Algorand’s utility beyond simple payments—enabling tokens, NFTs, and custom assets.

ASA Transfer Example

var transParams = algodApiInstance.TransactionParams();
ulong assetAmount = 10;

Transaction tx = Utils.GetTransferAssetTransaction(
    senderAddr: acct1.Address,
    receiverAddr: acct3.Address,
    assetId: assetID,
    amount: assetAmount,
    txnParams: transParams,
    closeRemainderTo: null,
    note: Encoding.UTF8.GetBytes("transfer message")
);

SignedTransaction signedTx = acct1.SignTransaction(tx);

try 
{
    TransactionID id = Utils.SubmitTransaction(algodApiInstance, signedTx);
    Console.WriteLine("Transaction ID: " + id.TxId);
    Console.WriteLine(Utils.WaitTransactionToComplete(algodApiInstance, id.TxId));
}
catch (Exception e)
{
    Console.WriteLine(e.Message);
}

This pattern applies to all ASA operations including creation, opt-in, freeze, and clawback.

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Building the UI with Avalonia

While .NET offers backend power, Avalonia brings true cross-platform GUI capabilities.

Why Avalonia?

Creating an Avalonia Project

  1. Install the Avalonia Visual Studio extension
  2. Create a new “Avalonia Application” project named algo_wallet_tutorial

  3. Choose between:

    • Code-behind: Simpler for small apps (used here)
    • MVVM: Better for complex state management

Designing the Interface

Here’s a simplified login dialog layout:

<Window xmlns="https://github.com/avaloniaui">
  <StackPanel Margin="20">
    <TextBlock Text="Enter Password" FontSize="16" Margin="0,0,0,10"/>
    <PasswordBox Name="passwordBox" Margin="0,0,0,20"/>
    <Button Name="btn_enterpsd_ok" Content="OK" HorizontalAlignment="Right" Width="80"/>
  </StackPanel>
</Window>

Handling Button Clicks in Code-Behind

public MainWindow()
{
    InitializeComponent();
    this.FindControl<Button>("btn_enterpsd_ok").Click += BtnEnterpsdClicked;
}

private void BtnEnterpsdClicked(object sender, RoutedEventArgs e)
{
    var btn = sender as Button;
    btn.Content = "Clicked";
}

This clean separation keeps logic manageable while enabling responsive interactions.

Secure Private Key Storage

One of the most critical aspects of any wallet is secure local key storage.

Security Requirements

  1. Never store raw private keys
  2. Encrypt keys using strong algorithms
  3. Only unlockable with user password
  4. Support optional portability across devices

Encryption Strategy: Scrypt + AES-GCM

We combine two proven techniques:

Key Derivation Process

  1. Generate 16-byte random salt → store locally
  2. Use Scrypt to derive 48-byte hash from password + salt

  3. Split hash:

    • First 16 bytes → checksum (for password verification)
    • Last 32 bytes → AES encryption key
  4. Encrypt master key using AES-GCM with fixed nonce (for portability)

Decryption Flow

  1. Recompute Scrypt hash from input password and stored salt
  2. Compare first 16 bytes with stored checksum
  3. If match, decrypt master key using derived AES key
🔒 Using BouncyCastle ensures FIPS-compliant cryptography without dependencies on platform-specific APIs.

👉 Secure your blockchain applications with best-in-class infrastructure.

Frequently Asked Questions (FAQ)

Q: Can I run this wallet on Linux or macOS?
A: Yes! Thanks to .NET 6+ and Avalonia, the app compiles and runs natively on all major operating systems.

Q: Is the private key encryption method safe against brute-force attacks?
A: Yes. Scrypt is memory-hard and resistant to GPU/ASIC cracking. Combined with AES-GCM, it meets modern security standards.

Q: Can users migrate their wallets between different apps?
A: Only if they use compatible encryption schemes. Our method allows migration by using a fixed nonce ("algo--wallet"), but you can disable this for higher security.

Q: How do I handle transaction fees dynamically?
A: Use algodApiInstance.TransactionParams() before each transaction to get current suggested fees.

Q: What’s the difference between .axaml and .xaml files?
A: .axaml is Avalonia’s custom extension introduced in v0.9.11 to avoid conflicts with Visual Studio’s built-in XAML processing.

Q: Where can I find documentation for the Algorand .NET SDK?
A: Official tutorials are available at developer.algorand.org, including guides on account management and ASA operations.

Conclusion

Building a cross-platform Algorand wallet in C# is not only feasible but efficient thanks to mature libraries like dotnet-algorand-sdk and Avalonia. From connecting to the network and managing transactions to designing responsive UIs and securing private keys, this guide covers the essential pillars of wallet development.

By leveraging .NET’s performance and security stack, developers can create professional-grade blockchain applications that are maintainable, extensible, and ready for real-world use.

Whether you're extending this project into a full DeFi suite or learning blockchain fundamentals, this foundation sets you on the right path.

🚀 Want to go further? Integrate real-time price feeds, QR code scanning, or hardware wallet support to elevate your wallet experience.