pbkdf2 problem when compare password with the hash on mysql

Question

i have a problem when i want to compare my password with that password that hashed in mysql database and always say incorrect while i login it is my code for hashing and comparing:

 

 

class Hashing
 {
     const int salt_size = 32;
     const int hash_size = 32;
     const int iteration = 167319;

     public static string Generate(string password)
     {

         var salt = new byte[salt_size];
         using (RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider()) {
             rng.GetBytes(salt);
         }


         using (Rfc2898DeriveBytes pbkdf2 = new Rfc2898DeriveBytes(password, salt, iteration))
         {
             byte[] hash = pbkdf2.GetBytes(salt_size);


             return Convert.ToBase64String(salt) + "|" + iteration + "|" + Convert.ToBase64String(hash);
         }


     }

     public static bool isCorrect(string pass,string hash)
     {


         string[] hashsplit = hash.Split('|');
         byte[] salt = Convert.FromBase64String(hashsplit[0]);
         int iteration = Int32.Parse(hashsplit[1]);
         string hashed = hashsplit[2];


         using (Rfc2898DeriveBytes pbkdf2 = new Rfc2898DeriveBytes(pass,salt,iteration))
         {
             byte[] Hash = pbkdf2.GetBytes(salt_size);


             if (hashed == Convert.ToBase64String(Hash))
             {
                 return true;
             }
             else
             {

                 return false;
             }
         }

     }
 }

 

and this code is for checking username and password from mysql:

 

class Lg : Msql_connection
 {

     private string username { set; get; }
     private string pass { set; get; }

     public bool validate_Login(string username, string pass)
     {
         bool check = false;
         MySqlDataReader mdr;
         MySqlDataReader mdr2;
         MySqlDataReader mdr3;
         string passw = "";
         using (MySqlCommand mcmd3 = new MySqlCommand())
         {
             mcmd3.CommandText = "select password from login";
             mcmd3.Connection = msc;
             msc.Close();
             msc.Open();
             mdr3 = mcmd3.ExecuteReader();
             if (mdr3.Read())
             {
                 passw = mdr3["password"].ToString();
             }
             msc.Close();
         }

             using (MySqlCommand mcmd2 = new MySqlCommand())
         {
             mcmd2.CommandText = "select hid,attempt,time from login_attempt";
             mcmd2.Connection = msc;

             msc.Close();
             msc.Open();
             mdr2 = mcmd2.ExecuteReader();

             if (mdr2.Read()&&int.Parse(mdr2["attempt"].ToString()) < 4)
             {
                 using (MySqlCommand mcmd = new MySqlCommand())
                 {
                     mcmd.CommandText = "select username,password from login where binary username=@user and password=@pass";
                     mcmd.Connection = msc;
                     msc.Close();
                     msc.Open();
                     mcmd.Parameters.Add("@user", MySqlDbType.VarChar).Value = this.username=username;
                     mcmd.Parameters.Add("@pass", MySqlDbType.Text).Value = this.pass = Hashing.isCorrect(pass, passw).ToString();
                     mdr = mcmd.ExecuteReader();

                     if (mdr.HasRows)
                     {

                         if (mdr.Read())
                         {
                             reset_Attempt();
                             MessageBox.Show("correct");
                             check = true;
                         }
                     }
                     else
                     {
                         check = false;
                         update_Attempt();

                         MessageBox.Show("incorrect");
                     }
                 }

             }
             else if (int.Parse(mdr2["attempt"].ToString()) >= 4)
             {
                 check = false;
                 MessageBox.Show("You have been restrict");
                 set_time();

             }

         }

         msc.Close();

         return check;
     }
}