public int Id {get;set;}
public string Username { get; set; }
public string Pwd { get; set; }

public class ConfirmPassword : IValidatableObject
{
    [Required]
    public string Password { get; set; }
    [Required(ErrorMessage="Confirm Password field is required.")]
    public string ConfirmPwd { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        string regex1 = @"^.{8,10}$";                   // 8 - 10 characters

        Match requirement1 = Regex.Match(Password, regex1);

        if (Password != ConfirmPwd)
            yield return new ValidationResult("Password and Confirm Password is not identical.");

        if (!requirement1.Success)
            yield return new ValidationResult("Password must be between 8 and 10 characters.");


    }
}

namespace
{
    public class User
    {
public int Id {get;set;}
public string Username { get; set; }
public string Pwd { get; set; }

    }
}


namespace
{
    public class ConfirmPassword : IValidatableObject
    {
        [Required]
        public string Password { get; set; }
        [Required(ErrorMessage="Confirm Password field is required.")]
        public string ConfirmPwd { get; set; }

        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
        {
            string regex1 = @"^.{8,10}$";                   // 8 - 10 characters
            string regex2 = @"(?:.*?[A-Z]){1}";             // 1 uppercase
            string regex3 = "";             // 1 lowercase
            string regex4 = "";                // 1 numeric

            Match requirement1 = Regex.Match(Password, regex1);
            Match requirement2 = Regex.Match(Password, regex2);
            Match requirement3 = Regex.Match(Password, regex3);
            Match requirement4 = Regex.Match(Password, regex4);

            if (Password != ConfirmPwd)
                yield return new ValidationResult("Password and Confirm Password is not identical.");

            if (!requirement1.Success)
                yield return new ValidationResult("Password must be between 8 and 10 characters.");

            if (!requirement2.Success)
                yield return new ValidationResult("Password must contain at least 1 uppercase letter.");

            if (!requirement3.Success)
                yield return new ValidationResult("Password must contain at least 1 lowercase letter.");

            if (!requirement4.Success)
                yield return new ValidationResult("Password must contain at least 1 numeric character.");

        }
    }
}

public LoginViewModel()
{
  [Required]
  public string LoginId {get; set;}

  [DataType(DataType.Password)]
  public string Password {get; set;}

  [DataType(DataType.Password)]
  public string ConfirmPassword {get; set;}

 // this validation is not db related and can be done client side...
 public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        string regex1 = @"^.{8,10}$";                   // 8 - 10 characters

        Match requirement1 = Regex.Match(Password, regex1);

        if (Password != ConfirmPwd)
            yield return new ValidationResult("Password and Confirm Password is not identical.");

        if (!requirement1.Success)
            yield return new ValidationResult("Password must be between 8 and 10 characters.");


    }

}

[HttpGet]
public ActionResult Login()
{
   var model = new LoginViewModel();

   return View("Login",model);
}

[HttpPost]
public ActionResult Login(LoginViewModel model)
{

   var user = GetUserFromRepositoryByUsername(model.username);

   if(user != null)
    {
      if(user.password == model.Password)
      {
        RedirectToAction("YouLoggedInYay!");
      }
    }

    // if we made it this far, the user didn't exist or the password was wrong.
    // Highlight the username field red and add a validation error message.
    ModelState.AddError("Username","Your credentials were invalid punk!");

   return View("Login",model);
}

public class ConfirmPassword
{
    User model;

    [Required]
    public string Username
    {
        get { return this.model.Username; }
        set { this.model.Username = value; }
    }
    [Required]
    [DataType(DataType.Password)]
    public string Password
    {
        get { return this.model.Pwd; }
        set { this.model.Pwd = value; }
    }

    [Required(ErrorMessage = "Confirm Password field is required.")]
    [Compare("NewPassword",
       ErrorMessage = "The new password and confirmation password do not match.")]
    [RegularExpression(@"^.{8,10}$")]
    [DataType(DataType.Password)]
    public string ConfirmPwd { get; set; }

    public ConfirmPassword()
    {
        this.model = new User();
    }

    public ConfirmPassword(User model)
    {
        this.model = model;
    }

}