using System;
using System.Runtime.InteropServices;
using System.Security;

namespace ConsoleApp138
{
    class Program
    {
        [DllImport("kernel32.dll" )]
        private static extern IntPtr LoadLibrary( IntPtr str);
        [DllImport("kernel32.dll")]
        private static extern IntPtr GetProcAddress(IntPtr lib, IntPtr str);

        /// <summary>
        /// Declare our unknown function (in this case messagebox)
        /// </summary>
        /// <returns></returns>
        delegate int UnknownFunction(int a, string x, string y, int z);


        /// <summary>
        /// Invented and created by gigajew @ www.hackforums.net
        /// Afaik first of it's kind
        /// </summary>
        static void Main(string[] args)
        {
             // call user32!MessageBoxA
            Example1();

            // call user32!MessageBoxA
            Example2();
        }

        static void Example2()
        {
            SecureString ker = new SecureString();
            ker.AppendChar('U');
            ker.AppendChar('s');
            ker.AppendChar('e');
            ker.AppendChar('r');
            ker.AppendChar('3');
            ker.AppendChar('2');
            ker.AppendChar('.');
            ker.AppendChar('d');
            ker.AppendChar('l');
            ker.AppendChar('l');
            SecureString mes = new SecureString();
            mes.AppendChar('M');
            mes.AppendChar('e');
            mes.AppendChar('s');
            mes.AppendChar('s');
            mes.AppendChar('a');
            mes.AppendChar('g');
            mes.AppendChar('e');
            mes.AppendChar('B');
            mes.AppendChar('o');
            mes.AppendChar('x');
            mes.AppendChar('A');
            UnknownFunction unknownFunction1 = GetProcedureSecure<UnknownFunction>(ker, mes);
            unknownFunction1(0, "Hello world 2 ", "Title 2", 2);

        }

        static void Example1()
        {
            SecureString ker = new SecureString();
            ker.AppendChar('U');
            ker.AppendChar('s');
            ker.AppendChar('e');
            ker.AppendChar('r');
            ker.AppendChar('3');
            ker.AppendChar('2');
            ker.AppendChar('.');
            ker.AppendChar('d');
            ker.AppendChar('l');
            ker.AppendChar('l');
            IntPtr lib = LoadLibrarySecure(ker);

            SecureString mes = new SecureString();
            mes.AppendChar('M');
            mes.AppendChar('e');
            mes.AppendChar('s');
            mes.AppendChar('s');
            mes.AppendChar('a');
            mes.AppendChar('g');
            mes.AppendChar('e');
            mes.AppendChar('B');
            mes.AppendChar('o');
            mes.AppendChar('x');
            mes.AppendChar('A');
            IntPtr proc = GetProcAddressSecure(lib, mes);

            UnknownFunction unknownFunction1 = Marshal.GetDelegateForFunctionPointer(proc, typeof(UnknownFunction)) as UnknownFunction;
            unknownFunction1(0, "Hello world", "Title", 0);
        }

        static T GetProcedureSecure<T>(SecureString library, SecureString procedure) where T: class
        {
            IntPtr lib = LoadLibrarySecure(library);
            IntPtr proc = GetProcAddressSecure(lib, procedure);
            T del = Marshal.GetDelegateForFunctionPointer(proc, typeof(T)) as T;
            return del;
        }

        static IntPtr LoadLibrarySecure(SecureString secure )
        {
            IntPtr ptr = Marshal.SecureStringToGlobalAllocAnsi(secure);
            IntPtr lib =  LoadLibrary(ptr);
            if(Equals(lib, IntPtr.Zero) )
            {
                throw new Exception("Couldn't load library");
            }
            Marshal.ZeroFreeGlobalAllocAnsi(ptr);
            return lib;
        }

        static IntPtr GetProcAddressSecure(IntPtr lib, SecureString secure )
        {
            IntPtr ptr = Marshal.SecureStringToGlobalAllocAnsi(secure);
            IntPtr func = GetProcAddress(lib, ptr);
            if(Equals(func, IntPtr.Zero))
            {
                throw new Exception("Couldn't find procedure");
            }
            Marshal.ZeroFreeGlobalAllocAnsi(ptr);
            return func;

        }
    }
}