Key Verification

In this example, our aim is to quickly implement the basic licensing functionality into your application.

We assume you have created an project using Visual Studio 2017 and added Cryptolens.Licensing (see this tutorial).

If you would experience any issues, please check common errors section.

Example

It is quite easy to verify a license. This can be done with the code snippet below. In order to make it work, you need to change three parameters:

• RSAPubKey - you can find this key on this page, by going to the API Keys section.
• Access Token - you can find this key on this page, by going to the API Keys section.
• ProductId - you can find it on the product page, which you can find more about here.

For production use cases, it is better to create a specific access token as described here.

The code below should be included whenever you want to verify a license key, which intuitively happens during app start (eg. Form_Load for desktop apps). In addition, you can invoke it whenever a user updates the license key.

Adding namespaces in C#

using SKM.V3;
using SKM.V3.Methods;
using SKM.V3.Models;

Adding namespaces in VB.NET

Imports SKM.V3
Imports SKM.V3.Methods
Imports SKM.V3.Models

Key verification in C#

var licenseKey = "GEBNC-WZZJD-VJIHG-GCMVD";
var RSAPubKey = "{enter the RSA Public key here}";

var auth = "{access token with permission to access the activate method}";
var result = Key.Activate(token: auth, parameters: new ActivateModel()
{
    Key = licenseKey,
    ProductId = 3349,
    Sign = true,
    MachineCode = Helpers.GetMachineCode()
});

if (result == null || result.Result == ResultType.Error ||
    !result.LicenseKey.HasValidSignature(RSAPubKey).IsValid())
{
    // an error occurred or the key is invalid or it cannot be activated
    // (eg. the limit of activated devices was achieved)
    Console.WriteLine("The license does not work.");
}
else
{
    // everything went fine if we are here!
    Console.WriteLine("The license is valid!");
}

Console.ReadLine();

Key verification in VB.NET

Dim licenseKey = "GEBNC-WZZJD-VJIHG-GCMVD"
Dim RSAPubKey = "{enter the RSA Public key here}"

Dim auth = "{access token with permission to access the activate method}"

Dim result = Key.Activate(token:=auth, parameters:=New ActivateModel() With {
                          .Key = licenseKey,
                          .ProductId = 3349,
                          .Sign = True,
                          .MachineCode = Helpers.GetMachineCode()
                          })

If result Is Nothing OrElse result.Result = ResultType.[Error] OrElse
    Not result.LicenseKey.HasValidSignature(RSAPubKey).IsValid Then
    ' an error occurred or the key is invalid or it cannot be activated
    ' (eg. the limit of activated devices was achieved)
    Console.WriteLine("The license does not work.")

Else
    ' everything went fine if we are here!
    Console.WriteLine("The license is valid!")
End If

Common errors

.NET Core issues

The Helpers.GetMachineCode() method is currently not supported on the .NET Core. MachineCode can be any value that allows you to uniquely identify an end user (eg. their computer).

Namespaces missing

This means that Cryptolens.Licensing library was not included into the project. It can be easily added using NuGet packager manager, which you can find by right clicking on the project:

Note, Cryptolens.Licensing has nothing in common with SKGL. There is no need to include SKGL.

Result is null

In most cases, this is because some of the required parameters are missing. These are:

• RSAPubKey
• auth
• ProductId

It can also be that the licenseKey is missing. Please check the beginning of the tutorial on how to find them.

Note, if you have blocked a license key, it will also return a null result.