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NEO Lux

NEO light wallet / blockchain API for C#.

Contents

• Description
• Compatibility
• Installation
• Usage
• Console Demo
• Light Wallet Demo
• Unity Support
• Transaction Listening
• Advanced operations
• TODO
• Credits and License

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Description

NEO Lux was developed to provide an easy way to interact with Smart Contracts in the NEO blockchain using C#.

It is not necessary to run a full node, because NEO Lux connects to Neon DB, which is the same API used by the Neon wallet.

Compatibility

Platform	Status
.NET framework	Working
UWP	Working
Mono	Working
Xamarin / Mobile	Untested
Unity	Working

Installation

PM> Install-Package NeoLux

Usage

Import the package:

using Neo.Lux;

For invoking a Smart Contract, e.g.:

	var privKey = "XXXXXXXXXXXXXXXXprivatekeyhereXXXXXXXXXXX".HexToBytes();	 // can be any valid private key
	var myKeys = new KeyPair(privKey);
	var scriptHash = "de1a53be359e8be9f3d11627bcca40548a2d5bc1"; // the scriptHash of the smart contract you want to use	
	// for now, contracts must be in the format Main(string operation, object[] args)
	var api = NeoDB.ForMainNet();
	var result = api.CallContract(myKeys, scriptHash, "registerMailbox", new object[] { "ABCDE", "[email protected]" });

For transfering assets (NEO or GAS), e.g.:

	var privKey = "XXXXXXXXXXXXXXXXprivatekeyhereXXXXXXXXXXX".HexToBytes();	 
	// can be any valid private key in raw format, for WIF use KeyPair.FromWIF
	var myKeys = new KeyPair(privKey);
	// WARNING: For now use test net only, this code is experimental, you could lose real assets if using main net
	var api = NeoDB.ForTestNet();
	var result = api.SendAsset("AanTL6pTTEdnphXpyPMgb7PSE8ifSWpcXU" /*destination address*/, "GAS", 3 /*amount to send */ , myKeys);

For getting the balance of an address:

	var api = NeoDB.ForTestNet();
	var balances = api.GetBalancesOf("AYpY8MKiJ9q5Fpt4EeQQmoYRHxdNHzwWHk");
	foreach (var entry in balances)
	{
		Console.WriteLine(entry.Key + " => " + entry.Value);
	}

NEP5 Token support

Neo-Lux allows to abstract interaction with Neo tokens via the NEP5 C# class.

Here's an example of interaction with a NEP5 token:

	var api = NeoDB.ForMainNet(); 
	var redPulse_token = api.GetToken("RPX");	
	Console.WriteLine($"{redPulse_token.Name} ({redPulse_token.Symbol})");
	Console.WriteLine($"Total Supply: {redPulse_token.TotalSupply} ({redPulse_token.Symbol})");
	
	// you can also request transfers of tokens
	var privKey = "XXXXXXXXXXXXXXXXprivatekeyhereXXXXXXXXXXX".HexToBytes();	 // can be any valid private key
	var myKeys = new KeyPair(privKey);
	redPulse_token.Transfer(myKeys, "AanTL6pTTEdnphXpyPMgb7PSE8ifSWpcXU" /*destination*/, 123 /*amount to send*/); 

You can also instantiate a NEP5 token from a script hash.

Look up the script hashes here or use your own if you're developing your own NEP5 token.

	var api = NeoDB.ForMainNet(); 	
	var redPulse_contractHash = "ecc6b20d3ccac1ee9ef109af5a7cdb85706b1df9";
	var redPulse_token = new NEP5(api, redPulse_contractHash);

Console Demo

A console program is included to demonstrate common features:

• Loading private keys
• Obtaining wallet address from private key
• Query balance from an address
• Invoking a NEP5 Smart Contract (query symbol and total supply)

Light Wallet Demo

A winforms demo is included to showcase how simple is to create a light wallet.

The light wallet demo is able to login into any wallet by inserting a private key in either raw format or WIF format, and also to transfer funds (NEO or GAS) to any address.

Please beware of using this wallet to transfer funds in Neo main net, as this wallet was created just for demonstration purpose and not exhaustively tested.

City of Zion cannot be responsibilized for loss of funds caused by using this light wallet.

Unity Support

NEOLux can be used together with Unity to make games that interact with the NEO blockchain. A Unity demo showcasing loading a NEO wallet and querying the balance is included.

Use caution, as most NEOLux methods are blocking calls; in Unity the proper way to call them is using Coroutines.

    IEnumerator SyncBalance()
    {
        var balances = NeoAPI.GetBalance(NeoAPI.Net.Test, this.keys.address);
        this.balance = balances["NEO"];
    }
	
	// Then you call the method like this
	StartCoroutine(SyncBalance());

Note: If you get compilation errors in Unity uou will need to go to Settings -> Player and change the Scripting Runtime version to .NET 4.6 equivalent

Using with Unity

In order to get the demo running in Unity, you'll want to open Unity and then open a new project. Open the folder located here.

Next, you'll want to open the Assets menu in your toolbar and import an asset package. This package can be found here.

You should now be able to hit play and see the demo in action!

If you're still receiving errors in the Console window, you'll want to go to Unity's Build Settings > Player Settings > and set the API compatibility level to .NET 4.6.

Airdrop / Snapshots

Latest versions of NEOLux have support for doing snapshots of the blockchain. This can be useful for example to find every wallet with a certain token balance at a certain date. Running a full local node using neo-cli full synced is extremely recommended when using snapshot features.

The following code extracts all transactions related to a specific NEP5 token.

	var api = new LocalRPCNode(10332, "http://neoscan.io");

	uint startBlock = 2313827;
	uint endBlock = 2320681;

	var token = api.GetToken("SOUL");
	var soul_tx = SnapshotTools.GetTokenTransactions(token, startBlock, endBlock);
	var soul_lines = new List<string>();
	foreach (var tx in soul_tx)
	{
		soul_lines.Add(tx.Hash+","+tx.Serialize().ByteToHex());
	}
	File.AppendAllLines("soul_txs.txt", soul_lines.ToArray());

Transaction Listening

Many applications will need to react to certain transactions once they appear on the chain. The ScriptInspector class can be used for decoding contract calls along with their arguments.

// First declare a BlockIterator
var iterator = new BlockIterator(api);
var targetContractHash = "AY9o94nWrUCEJ29UWhAodaJjQ16byjH852".AddressToScriptHash();
var token = new NEP5(api, targetContractHash);
var targetAddress = "AY9o94nWrUCEJ29UWhAodaJjQ16byjH852";

// You can listen for specific transactions of a specific type
var tx = api.WaitForTransaction(iterator, x => x.type == TransactionType.ContractTransaction);
if (tx != null) {
	Console.WriteLine($"Transaction {tx.Hash} is a asset transfer");
}

// You can listen for specific transactions arriving to a specific address 
var tx = api.WaitForTransaction(iterator, x => x.HasOutput(targetAddress));
if (tx != null) {
	Console.WriteLine($"Transaction {tx.Hash} was sent to {targetAddress}");
}

// You can listen for specific transactions coming from a specific address 
var tx = api.WaitForTransaction(iterator, x => x.HasInput(targetAddress));
if (tx != null) {
	Console.WriteLine($"Transaction {tx.Hash} was sent from {targetAddress}");
}

// You can listen for specific transactions that contain certain contract operations
var tx = api.WaitForTransaction(iterator, x => new ScriptInspector(x.script, targetContractHash).Any(y => y.operation == "transfer"));
if (tx != null) {
	Console.WriteLine($"Transaction {tx.Hash} contains transfer for {token.Name}");
	var inspector = new ScriptInspector(tx.script);
	foreach (var call in inspector.Calls) {
		if (call.operation == "transfer") {
			var from = new UInt160(call.arguments[0]);
			var to = new UInt160(call.arguments[1]);
			var amount = new BigInteger(call.arguments[2]);
			Console.WriteLine($"Transfer of {amount} from {from.ToAddress()} to {to.ToAddress()});
		}
	}
}

// You can listen for specific transactions that contain certain new contract deployments
var tx = api.WaitForTransaction(iterator, x => new ScriptInspector(x.script, targetContractHash).Deployments.Any());
if (tx != null) {
	Console.WriteLine($"Transaction {tx.Hash} deployed a new contract");
}

Advanced operations

NEOLux supports some advanced transaction operations specially useful for those doing an ICO in NEO.

Withdrawing NEO from an ICO contract address

After an ICO finishes, it is necessary to withdraw the received funds outside of the contract address. Now the problem is, for contracts the private key is not known.

// first read the AVM bytecode from the disk. This AVM must be exactly the same deployed in the main net
var bytes = System.IO.File.ReadAllBytes(@"d:\code\crypto\my_ico\MyICOContract.avm");

// the team keys must match what is written in the contract. Usually only a single address will have withdraw permissions
var team_keys = Neo.Lux.Cryptography.KeyPair.FromWIF("XXXXXXXXXXXXXX");

var ICO_address = "AY9o94nWrUCEJ29UWhAodaJjQ16byjH852"; // this should be the contract address, the one where the sale funds are stored

// finally, execute the withdraw. It is recommended to first try withdrawing a small amount and check if the transaction gets accepted
var amount = 50;
var tx = api.WithdrawAsset(team_keys, ICO_address, "NEO", amount, bytes);
if (tx != null){
	Console.WriteLine("Unconfirmed tx " + tx.Hash);
}
else {
	Console.WriteLine("Sorry, transaction failed");
}

Claiming GAS from an ICO contract address

After an ICO finishes, if the sale received tons of NEO but you don't withdraw it right away, then the address will have a large amount of unclaimed GAS. With NEOLux it is possible to claim it, and later send it to another address using the withdraw method.

// first read the AVM bytecode from the disk. This AVM must be exactly the same deployed in the main net
var bytes = System.IO.File.ReadAllBytes(@"d:\code\crypto\my_ico\MyICOContract.avm");

// the team keys must match what is written in the contract. Usually only a single address will have withdraw permissions
var team_keys = Neo.Lux.Cryptography.KeyPair.FromWIF("XXXXXXXXXXXXXX");

var ICO_address = "AY9o94nWrUCEJ29UWhAodaJjQ16byjH852"; // this should be the contract address, the one where the sale funds are stored

// execute the claim. Note that this operation is quite slow and can take several seconds to execute the transaction
var amount = 50;
var tx = api.ClaimGas(team_keys, ICO_address, bytes);
if (tx != null){
	Console.WriteLine("Unconfirmed tx " + txw.Hash);
}
else {
	Console.WriteLine("Sorry, transaction failed");
}

After the GAS is claimed it is available and you can use api.WithdrawAsset() to move it to other address.

Credits and License

Created by Sérgio Flores (http://lunarlabs.pt/).

Credits also go to the other devs of City Of Zion(http://cityofzion.io/), as this project started as a port of code from their NEON wallet from Javascript to C#. Of course, credits also go to the NEO team(http://neo.org), as I also used some code from their NEO source.

This project is released under the MIT license, see LICENSE.md for more details.