using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp6
{
    public partial class Form1 : Form
    {
        ConversionHandler c = new ConversionHandler();
        private HMAC myMAC;

        public void MACHandler()
        {
            myMAC = new System.Security.Cryptography.HMACMD5();
        }

        public bool CheckAuthenticity(byte[] mes, byte[] mac, byte[] key)
        {
            myMAC.Key = key;
            if (CompareByteArrays(myMAC.ComputeHash(mes), mac, myMAC.HashSize / 8) == true)
            { return true; }
            else
                return false;
        }
        public byte[] ComputeMAC(byte[] mes, byte[] key)
        {
            myMAC.Key = key;
            return myMAC.ComputeHash(mes);
        }
        public int MACByteLength()
        {
            return myMAC.HashSize / 8;
        }

        private bool CompareByteArrays(byte[] a, byte[] b, int len)
        {
            for (int i = 0; i < len; i++)
                if (a[i] != b[i])
                    return false;
            return true;
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }


        private void button1_Click(object sender, EventArgs e)
        {
            MD5CryptoServiceProvider myMD5 = new MD5CryptoServiceProvider();
            byte[] hashValue = myMD5.ComputeHash(c.StringToByteArray(textBox1.Text));
            textBox3.Text = c.ByteArrayToHexString(hashValue);

        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox4_TextChanged(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            MACHandler();
            byte[] rezultat = ComputeMAC(c.StringToByteArray(textBox1.Text), c.StringToByteArray(textBox4.Text));


            textBox2.Text = c.ByteArrayToHexString(rezultat);
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox1_TextChanged_1(object sender, EventArgs e)
        {

        }

        private void button3_Click(object sender, EventArgs e)
        {
            MACHandler();
            byte[] rezultat = ComputeMAC(c.StringToByteArray(textBox1.Text), c.StringToByteArray(textBox4.Text));
            if (CheckAuthenticity(c.StringToByteArray(textBox1.Text), rezultat,  c.StringToByteArray(textBox4.Text)) == true)
            { System.Windows.Forms.MessageBox.Show("MAC OK !!!"); }
            else { System.Windows.Forms.MessageBox.Show("MAC NOT OK !!!"); }
        }
    }
}