Cryptographically Random Password / Data Set Creator using WPF, MVVM, and TPL

using System;
using System.Collections.ObjectModel;
using System.Windows.Input;
using RandPasswordGen.Helpers;
using RandPasswordGen.Models;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;


namespace RandPasswordGen.ViewModels
{
	public class MainWindowViewModel : BaseViewModel
	{
		private const int NUM_PASS_DEFAULT = 10, PASS_LEN_DEFAULT = 12;

		private RandPasswordModel _Model;
		public RandPasswordModel Model
		{
			get { return this._Model; }
			set
			{
				if (this._Model != value)
				{
					this._Model = value;
					RaisePropertyChanged(() => Model);
				}
			}
		}

		private StatsModel _StatsModel;
		public StatsModel StatsModel
		{
			get { return this._StatsModel; }
			set
			{
				if (this._StatsModel != value)
				{
					this._StatsModel = value;
					RaisePropertyChanged(() => StatsModel);
				}
			}
		}

		private string _AppStatus;
		public string AppStatus
		{
			get { return this._AppStatus; }
			set
			{
				if (this._AppStatus != value)
				{
					this._AppStatus = value;
					RaisePropertyChanged(() => AppStatus);
				}
			}
		}


		#region Commands

		public ICommand GeneratePassesCommand { get { return new DelegateCommand(GeneratePasswords); } }
		public ICommand SetDefaultsCommand { get { return new DelegateCommand(SetDefaults); } }

		#endregion

		#region Ctor
		public MainWindowViewModel()
		{
			AppStatus = "Idle";

			SetDefaults();
		}
		#endregion

		#region Command Handlers


		private void SetDefaults()
		{
			string chars = @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*()";
			char[] allowableChars = chars.ToCharArray();
			Model = new RandPasswordModel(PASS_LEN_DEFAULT, allowableChars, NUM_PASS_DEFAULT);
			StatsModel = new StatsModel(Model.GeneratedPass);
		}

		private void GeneratePasswords()
		{
			AppStatus = "Generating passwords...";

			AsyncCallHelper.RunAync(() =>
			{
				List<string> passes = new List<string>(Model.NumPasses);
				Parallel.For(0, Model.NumPasses, i =>
				{
					int seed = RandomGenHelper.GetCryptographicallyRandomInt32();
					Random r = new Random(seed);
					string pass = RandomGenHelper.GeneratePassword(r, Model.Length, Model.AllowableChars);
					lock (passes)
					{
						passes.Add(pass);
					}
				} );

				Model.GeneratedPass = passes;
				StatsModel = new StatsModel(Model.GeneratedPass);

				AppStatus = string.Format("{0} passwords generated", Model.NumPasses);
			} );

		}


		#endregion

		
	}
}