Simple KeyValueStore that I wrote and was unable to use.

KeyValueStore.cs

public interface IKeyValueStore
{
  object this[string key] { get; set; }
}

public static class KeyValueStoreExtensions
{
	public static DateTime GetDateTime(this IKeyValueStore store, string key)
	{
		var val = store[key];
		if (val == null)
			return DateTime.MinValue;

		return DateTime.Parse(val.ToString());
	}
}

public class MemoryStore : Dictionary<string, object>, IKeyValueStore
{
}

public class RegistryStore : IKeyValueStore
{
	private MemoryStore _memoryStore = new MemoryStore();
	private string _keyName = string.Empty;

	public RegistryStore(string keyName)
	{
		if (string.IsNullOrEmpty(keyName))
			throw new ArgumentNullException("keyName");
		
		_keyName = keyName;
	}

	public object this[string key]
	{
		get
		{
			// Use a memory store as a cache to avoid hitting the registry on each request.
			if (!_memoryStore.ContainsKey(key))
				_memoryStore[key] = Registry.GetValue(_keyName, key, null);

			return _memoryStore[key];
		}
		set
		{
			_memoryStore[key] = value;
			Registry.SetValue(_keyName, key, value);
		}
	}
}

public class Storage
{
	private IKeyValueStore _store;

	public Storage()
		: this(new MemoryStore())
	{
		
	}

	public Storage(IKeyValueStore store)
	{
		_store = store;
	}

	public DateTime LastModifiedDate
	{
		get
		{
			return _store.GetDateTime("LastModifiedDate");
		}
		set
		{
			_store["LastModifiedDate"] = value;
		}
	}
}