remove license validation of MarkdownPad 2 by Mono Cecil

check.cs

// MarkdownPad2.Core.StartupHelper
public StartupResult Check(string key, string email)
{
    Mod mod = new Mod();
    bool flag = false;
    try
    {
        flag = mod.Verify(key, email);
    }
    catch (Exception)
    {
    }
    if (flag)
    {
        this._name = mod.get_Args().get_Name();
        this.IsProcessed = true;
        return StartupResult.Mod;
    }
    LicenseEngine licenseEngine = new LicenseEngine();
    bool flag2 = licenseEngine.VerifyLicense(key, email);
    if (flag2)
    {
        this._name = licenseEngine.License.Name;
        this.IsProcessed = true;
        return StartupResult.Oem;
    }
    return StartupResult.None;
}

LicenseEngine.cs

public bool VerifyLicense(string licenseKey, string email)
	{
		if (string.IsNullOrEmpty(licenseKey) || string.IsNullOrEmpty(email))
		{
			return false;
		}
		try
		{
			this.License = this.Decrypt(licenseKey);
			this.LicenseProcessed = true;
		}
		catch (System.FormatException exception)
		{
			LicenseEngine._logger.ErrorException("Bad license format", exception);
			MessageBoxHelper.ShowWarningMessageBox(LocalizationProvider.GetLocalizedString("License_BadFormat", false, "MarkdownPadStrings") + StringUtilities.GetNewLines(2) + LocalizationProvider.GetLocalizedString("License_PleaseVerify", false, "MarkdownPadStrings"), LocalizationProvider.GetLocalizedString("License_ErrorTitle", false, "MarkdownPadStrings"));
			bool result = false;
			return result;
		}
		catch (OpenSslException exception2)
		{
			LicenseEngine._logger.ErrorException("Error decrypting license", exception2);
			MessageBoxHelper.ShowWarningMessageBox(LocalizationProvider.GetLocalizedString("License_ErrorMessage", false, "MarkdownPadStrings") + StringUtilities.GetNewLines(2) + LocalizationProvider.GetLocalizedString("License_PleaseVerify", false, "MarkdownPadStrings"), LocalizationProvider.GetLocalizedString("License_ErrorTitle", false, "MarkdownPadStrings"));
			bool result = false;
			return result;
		}
		catch (System.Exception exception3)
		{
			LicenseEngine._logger.ErrorException("Error processing license: " + licenseKey, exception3);
			MessageBoxHelper.ShowErrorMessageBox(LocalizationProvider.GetLocalizedString("License_ErrorMessage", false, "MarkdownPadStrings") + StringUtilities.GetNewLines(2) + LocalizationProvider.GetLocalizedString("License_PleaseVerify", false, "MarkdownPadStrings"), LocalizationProvider.GetLocalizedString("License_ErrorTitle", false, "MarkdownPadStrings"), exception3, "");
			bool result = false;
			return result;
		}
		if (this.License == null || this.License.Email == null || this.License.Product == null)
		{
			return false;
		}
		bool flag = this.License.Email == email;
		bool flag2 = this.License.Product == "MarkdownPad2";
		return flag && flag2;
	}

LicenseEngine_m.cs

// MarkdownPad2.Licensing.LicenseEngine
private License Decrypt(string payload)
{
    return new License
    {
        Name = "MarkdownPad2 Cracker",
        Email = "[email protected]"
    };
}

// MarkdownPad2.Licensing.LicenseEngine
public bool VerifyLicense(string licenseKey, string email)
{
    this.License = this.Decrypt(licenseKey);
    this.LicenseProcessed = true;
    return true;
}

MarkdownPad_Cracker.cs

using System.Diagnostics;
using System.IO;
using System.Linq;
using Mono.Cecil;
using Mono.Cecil.Cil;
using Mono.Cecil.Rocks;

namespace MarkdownpadCracker
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var name = "MarkdownPad2.exe";
            if (args != null && args.Length == 1)
            {
                name = args[0];
            }

            var target = string.Format("{0}_bak.exe", name.Substring(0, name.LastIndexOf('.')));
            if (File.Exists(target))
            {
                File.Delete(target);
                Debug.WriteLine("remove " + target);
            }

            File.Copy(name, target);

            Debug.WriteLine("read assembly from " + name);
            var asm = AssemblyDefinition.ReadAssembly(name);

            const string TypeName = "LicenseEngine";
            const string DecryptName = "Decrypt";
            const string SetLicenseName = "set_License";
            var licenseEngine = asm.MainModule.Types.First(type => type.Name == TypeName);
            Debug.WriteLine(licenseEngine.FullName);

            var decrypt = licenseEngine.Methods.First(method => method.Name == DecryptName);
            var setLicense = licenseEngine.Methods.First(method => method.Name == SetLicenseName);

            const string LicenseName = "License";
            const string SetName = "set_Name";
            const string SetEmail = "set_Email";
            var license = asm.MainModule.Types.First(type => type.Name == LicenseName);
            Debug.WriteLine(license.FullName);

            var nameMethod = license.Methods.First(method => method.Name == SetName);
            Debug.WriteLine("method >>> " + nameMethod.Name);
            var emailMethod = license.Methods.First(method => method.Name == SetEmail);
            Debug.WriteLine("method >>> " + emailMethod.Name);

            var processor = decrypt.Body.GetILProcessor();

            var ins = decrypt.Body.Instructions;
            var i = 0;
            ins.Insert(i, processor.Create(OpCodes.Nop));
            i++;
           
            const string licenseFullName = "MarkdownPad2.Licensing.License";
            Debug.WriteLine("try to load {0}", licenseFullName);
            var tdLicense = asm.Modules.Select(module => module.Types.First(type => type.IsPublic && type.FullName == licenseFullName)).FirstOrDefault();
            var licenseConstructor = tdLicense.GetConstructors().First();
            var constructorRef = licenseConstructor.GetElementMethod();

            ins.Insert(i, processor.Create(OpCodes.Newobj, constructorRef));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Stloc_1));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldloc_1));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldstr, "Ur Name"));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Callvirt, nameMethod));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Nop));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldloc_1));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldstr, "[email protected]"));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Callvirt, emailMethod));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Nop));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldloc_1));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Stloc_0));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldloc_0));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Stloc_2));
            i++;
            //            ins.Insert(i, processor.Create(OpCodes.Br_S));
            //            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldloc_2));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ret));

            const string verifyName = "VerifyLicense";
            const string processName = "set_LicenseProcessed";
            var licenseType = asm.MainModule.Types.First(type => type.Name == TypeName);
            Debug.WriteLine(licenseType.FullName);
            var process = licenseType.Methods.First(method => method.Name == processName);
            var verify = licenseType.Methods.First(method => method.Name == verifyName);

            Debug.WriteLine("method >>> " + verify.Name);
            processor = verify.Body.GetILProcessor();
            ins = verify.Body.Instructions;
            //            ins.Clear();
            i = 0;
            ins.Insert(i, processor.Create(OpCodes.Nop));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldarg_0));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldarg_0));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldarg_1));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Call, decrypt));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Call, setLicense));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Nop));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldarg_0));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldc_I4_1));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Call, process));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Nop));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldc_I4_1));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Stloc_0));
            i++;
            //            ins.Insert(i, processor.Create(OpCodes.Br_S));
            //            i++;
            ins.Insert(i, processor.Create(OpCodes.Ldloc_0));
            i++;
            ins.Insert(i, processor.Create(OpCodes.Ret));

            asm.Write(name);
        }
    }
}