ssc3

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

namespace ssclab3
{
    public partial class Form1 : Form
    {
        MD5CryptoServiceProvider myMD5 = new MD5CryptoServiceProvider();
        RandomNumberGenerator rnd = RandomNumberGenerator.Create();
        byte[] input = new byte[20];
        byte[] hashValue;
        //generates some random input rnd.GetBytes(input);
        //computes the hash hashValue = myMD5.ComputeHash(input);
        private HashAlgorithm hashAlgorithm;
        private ConversionHandler convert = new ConversionHandler();
        private HMAC myMAC;
        private string comboBoxSelection;
        private string inputTextString;

        public void MACHandler(string name)
        {
            if (name.CompareTo("SHA1") == 0)
            {
                myMAC = new System.Security.Cryptography.HMACSHA1();
            }
            if (name.CompareTo("MD5") == 0)
            {
                myMAC = new System.Security.Cryptography.HMACMD5();
            }
            if (name.CompareTo("RIPEMD") == 0)
            {
                myMAC = new System.Security.Cryptography.HMACRIPEMD160();
            }
            if (name.CompareTo("SHA256") == 0)
            {
                myMAC = new System.Security.Cryptography.HMACSHA256();
            }
            if (name.CompareTo("SHA384") == 0)
            {
                myMAC = new System.Security.Cryptography.HMACSHA384();
            }
            if (name.CompareTo("SHA512") == 0)
            {
                myMAC = new System.Security.Cryptography.HMACSHA512();
            }
        }

        public HashAlgorithm selectAlgorithm(string name)
        {
            switch (name)
            {
                case "SHA1":
                    hashAlgorithm = SHA1.Create();
                    break;
                case "MD5":
                    hashAlgorithm = MD5.Create();
                    break;
                case "SHA256":
                    hashAlgorithm = SHA256.Create();
                    break;
            }
            return hashAlgorithm;
        }

        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 button1_MouseClick(object sender, MouseEventArgs e)
        {
            MACHandler(comboBoxSelection);
            selectAlgorithm(comboBoxSelection);
            input = convert.StringToByteArray(inputTextString);
            hashValue = hashAlgorithm.ComputeHash(input);
            label2.Text = convert.ByteArrayToHexString(hashValue);
        }

        private void comboBox1_SelectedValueChanged(object sender, EventArgs e)
        {
            ComboBox combobox = new ComboBox();
            comboBoxSelection = combobox.GetItemText(comboBox1.SelectedItem);
        }

        class ConversionHandler
        {

            public byte[] StringToByteArray(string s) { return CharArrayToByteArray(s.ToCharArray()); }

            public byte[] CharArrayToByteArray(char[] array) { return Encoding.ASCII.GetBytes(array, 0, array.Length); }

            public string ByteArrayToString(byte[] array)
            {
                return Encoding.ASCII.GetString(array);
            }


            public string ByteArrayToHexString(byte[] array) { string s = ""; int i; for (i = 0; i < array.Length; i++) { s = s + NibbleToHexString((byte)((array[i] >> 4) & 0x0F)) + NibbleToHexString((byte)(array[i] & 0x0F)); } return s; }

            public byte[] HexStringToByteArray(string s)
            {
                byte[] array = new byte[s.Length / 2]; char[] chararray = s.ToCharArray(); int i; for (i = 0; i < s.Length / 2; i++)
                {
                    array[i] = (byte)(((HexCharToNibble(chararray[2 * i]) << 4) & 0xF0) | ((HexCharToNibble(chararray[2 * i + 1]) & 0x0F)));

                }
                return array;
            }

            public string NibbleToHexString(byte nib) { string s; if (nib < 10) { s = nib.ToString(); } else { char c = (char)(nib + 55); s = c.ToString(); } return s; }

            public byte HexCharToNibble(char c)
            {
                byte value = (byte)c; if (value < 65)
                {
                    value = (byte)(value - 48);
                }
                else { value = (byte)(value - 55); }
                return value;
            }
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            inputTextString = textBox1.Text;
        }
    }
}