Settings.cs

using System;
using System.IO;
using System.Reflection;
using System.Security.Cryptography;
using System.Text;
using System.Xml.Serialization;
using Livet;

namespace Azyobuzi.HatenaDiaryClient.Models
{
    public class Settings : NotifyObject, ICloneable
    {
        private static readonly byte[] entropy = Encoding.UTF32.GetBytes("futonmofumofufutonmofumofu");

        private static readonly string settingsFile =
            Path.GetDirectoryName(Environment.GetCommandLineArgs()[0]) + @"\settings.xml";

        private Settings() { }

        string _HatenaId;
        [XmlIgnore]
        public string HatenaId
        {
            get
            { return _HatenaId; }
            set
            {
                if (_HatenaId == value)
                    return;
                _HatenaId = value;
                RaisePropertyChanged("HatenaId");
            }
        }
        
        string _Password;
        [XmlIgnore]
        public string Password
        {
            get
            { return _Password; }
            set
            {
                if (_Password == value)
                    return;
                _Password = value;
                RaisePropertyChanged("Password");
            }
        }

        public string EncryptedIdPassword { set; get; }

        private void Encrypt()
        {
            EncryptedIdPassword = Encoding.UTF32.GetString(
                ProtectedData.Protect(
                    Encoding.UTF32.GetBytes(string.Join(":", this.HatenaId, this.Password)),
                    entropy,
                    DataProtectionScope.LocalMachine
                ));
        }

        private void Decrypt()
        {
            var idPass = Encoding.UTF32.GetString(
                ProtectedData.Unprotect(
                    Encoding.UTF32.GetBytes(this.EncryptedIdPassword),
                    entropy,
                    DataProtectionScope.LocalMachine
                ))
                .Split(':');
            this.HatenaId = idPass[0];
            this.Password = idPass[1];
        }
        
        public static Settings Load()
        {
            try
            {
                using (var sr = new StreamReader(settingsFile, Encoding.UTF32))
                {
                    var xs = new XmlSerializer(typeof(Settings));
                    var re = (Settings)xs.Deserialize(sr);
                    re.Decrypt();
                    return re;
                }
            }
            catch
            {
                return new Settings();
            }
        }

        public void Save()
        {
            this.Encrypt();
            using (var sw = new StreamWriter(settingsFile, false, Encoding.UTF32))
            {
                var xs = new XmlSerializer(typeof(Settings));
                xs.Serialize(sw, this);
            }
        }

        public object Clone()
        {
            this.Save();
            return Load();
        }
    }
}