Libskycoin for .Net

.Net client library for Skycoin API. This library is a .Net assembly generated with SWIG to access Skycoin API from .Net.

Table of Contents

• Installation
• Using the API
  • Naming
  • Parameters
    • Handles
    • Byte Slices
    • Structures
    • Fixed Size Arrays
    • Other Slices
    • Memory Managemanet
• Make rules
• Development setup

Installation

Before installing, make sure you understand the choices available to install a Nuget package and the level of support in your platform for each possible configuration. For instance, in case of installing Nuget client tools the process would look like this, using dotnet add package command.

dotnet add package LibSkycoinNet

... or using Nuget install command ...

nuget install LibSkycoinNet

It is possible to install the package using Visual Studio Package Manager Console by executing the following command and then follow the instructions to install and use a package in Visual Studio.

Install-Package LibSkycoinNet

For getting similar results using a graphical IDE interface consider package name to be LibSkycoinNet and consult the articles listed below:

• Install and use a package in Visual Studio
• Package Manager UI reference for Windows users
• Including a NuGet package in your project using Mac OS

Install from sources

Download the repository from http://github.com/simelo/libskycoin-dotnet.git. Execute (nuget restore LibskycoinNet.sln) to install the library. Although executing (nuget install NUnit.Runners -Version 2.6.4 -OutputDirectory testrunner) is a better choice for making changes to the library. However, when using tox these commands are not required at all because calling tox will make any necessary installation and execute the tests.

Usage

Naming

The exported function in Libskycoin .NET have the following naming format: SKY_package_func_name where package is replace by the package where the original Skycoin function is and func_name is the name of the function. For example, LoadConfig function from cli package is called in .Net SKY_cli_LoadConfig

Parameters

All skycoin exported functions return an error object as the last of the return parameters. In .NET error is return as an uint and it is the first return parameter. The rest of the parameters are returned in the same order.

Receivers in Skycoin are the first of the input parameters. Simple types, like integer, float, string will be used as the corresponding types in .NET, except what act as pointers.

Handles

Some of Skycoin types are too complex to be exported to a scripting language. So, handles are used instead. Therefore all functions taking a complex type will receive a handle instead of the original Skycoin type. For example, having these functions exported from Skycoin:

  func LoadConfig() (Config, error)
  func (c Config) FullWalletPath() string

Config is a struct type that is treated as a handle in Libskycoin .Net . The usage in .Net will be:

using skycoin;
namespace LibskycoinNet
{
    public class Skycoin : skycoin.skycoin
    {
    public function main(){
      var configHandle = new_Config_HandlePtr();
      var err = SKY_cli_LoadConfig(configHandle);
      if(err == SKY_OK) {
        // SkY_OK means no error
        var fullWalletPath = new _GoString()_;
        err = SKY_cli_FullWalletPath(configHandle,fullWallerPath);
        Assert.AreEqual(err,SKY_OK);
        Console.WriteLine(fullWallerPath.p);

        //Close the handle after using the it
        //so the garbage collector can delete the object associated with  it.
        SKY_handle_close( configHandle );
      } else {
        #Error
        Console.WriteLine(err);
      }
    }
  }
}

Byte slices

Parameters of type byte[] will treated as string . Example, this function in Skycoin:

func (s ScryptChacha20poly1305) Encrypt(data, password []byte) ([]byte, error)

... should be invoked like this:

var encrypt_settings = new encrypt__ScryptChacha20poly1305();
var data = new GoSlice(); //It will be passed as a parameter of type []byte
var pwd = new GoSlice(); //As []byte too
var dataStr = new _GoString();
var pwdStr = new _GoString();
var encrypted = new GoSlice();

dataStr.setString("Data to encrypt" );
data.convertString(dataStr);
pwdStr.SetString("password");
pwd.convertString(pwdStr);

var err = SKY_encrypt_ScryptChacha20poly1305_Encrypt(encrypt_settings, data, pwd,encrypted);
if(err == SKY_OK){
  Console.WriteLine(encrypted.getString().p); //Encrypted is GoSlice
}

Structures

Structures that are not exported as handles are treated like .NET classes. In the previous example type ScryptChacha20poly1305 is created in .NET like:

var encrypt_settings = new encrypt__ScryptChacha20poly1305()

And passed as first parameter in call to SKY_encrypt_ScryptChacha20poly1305_Encrypt.

Fixed Sized Arrays

Parameters of fixed size array are wrapped in structures when called from .NET.

Given these types in Skycoin and this exported function:

  type PubKey [33]byte
  type SecKey [32]byte

  func GenerateDeterministicKeyPair(seed []byte) (PubKey, SecKey)

This is a way to use them to write assertions in .NET:

//Generates random seed
var data = new GoSlice();
var err = SKY_cipher_RandByte(32,data);

Assert.AreEqual(err,SKY_OK);

var pubkey = new cipher_PubKey();
var seckey = new cipher_SecKey();

err = SKY_cipher_GenerateDeterministicKeyPair(data, pubkey,seckey);

In the example above pubkey and seckey are objects of an structure type containing a field named data holding the corresponding instance of PubKey and SecKey. Something like:

  cipher_PubKey struct{
    data [33]byte;
  } cipher_PubKey;

  cipher_SecKey struct{
    data [32]byte;
  } ;

Other Slices

Other slices of base type different from byte are indeed wrapped inside classes. Let's see how to call the following function:

func GenerateDeterministicKeyPairs(seed []byte, n int) []SecKey

In C# this how it should be used to generate a deterministic sequence of pairs of public / private keys given a random seed:

//Generates random seed
var seed = new GoSlice();
var err = SKY_cipher_RandByte(32,seed);
var seckeys = new cipher__SecKeys();

err = SKY_cipher_GenerateDeterministicKeyPairs(seed, 2,seckeys);

for(int i=0;i<seckeys.count,i++){
  var pubkey = new cipher_PubKey();
  var seckey = new cipher_SecKey();
  seckeys.getAt(seckey,i);

  SKY_cipher_PubKeyFromSecKey(seckey, pubkey);
  err = SKY_cipher_PubKey_Verify(pubkey);
  Assert.AreEqual(err,SKY_OK);
}

Memory Management

Memory management is transparent to the user. Any object allocated inside the library is left to be managed by the .NET garbage collector.

Make Rules

The following make rules are available after git checkout of this repository. They all require Skycoin to be checked out as a git submodule of libskycoin .NET .

• build-libc
  • Compiles skycoin C language library.
• build-swig
  • Creates the wrapper C code to generate the .NET library.