public async Task <IActionResult> OnPostAsync()
        {
            if (!ModelState.IsValid)
            {
                return(Page());
            }

            string pw = Gebruiker.PASSWORD;

            var hashed = PasswordStorage.HashPassword(Encoding.UTF8.GetBytes(pw), PasswordStorage.GenerateSalt(), 50000);

            pw = Convert.ToBase64String(hashed);

            Gebruiker.PASSWORD = pw;

            _context.Users.Add(Gebruiker);
            await _context.SaveChangesAsync();

            return(RedirectToPage("./Index"));
        }