/// <summary>
/// Reads the high scores XML file and returns a collection of PlayerScore objects, each representing a high score
/// As the high scores XML file is encrypted, this method decypts it.
/// </summary>
/// <returns>A collection of PlayerScore objects representing the high scores</returns>
/// <exception cref="System.Exception">Error occured while reading data.</exception>
private List <PlayerScore> LoadScores()
{
if (File.Exists(FileName))
{
try
{
//read the XML file
XmlDocument xmlDoc = new XmlDocument
{
PreserveWhitespace = true
};
xmlDoc.Load(FileName);
// Create a new RSA key. This key will encrypt a symmetric key,
// which will then be imbedded in the XML document.
//need to move the key into the webconfig
CspParameters parameters = new CspParameters
{
KeyContainerName = ConfigurationSettings.AppSettings["ScoresFileEncryptionKey"]
//KeyContainerName = "XML_ENC_RSA_KEY"
};
RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(parameters);
// Decrypt the "Player" element.
TrippleDESDocumentEncryption.Decrypt(xmlDoc, rsaKey, "rsaKey");
List <PlayerScore> list = new List <PlayerScore>(); //Create a new list
XmlNodeList elementsByTagName = null;
elementsByTagName = xmlDoc.GetElementsByTagName(HIGHSCORE); //find each score entry in the XML file
foreach (XmlNode node in elementsByTagName)
{
//for each score found in the XML file, create a new PlayerScore object with the data
PlayerScore item = new PlayerScore
{
Player = node[PLAYER].InnerText,
Score = Convert.ToInt32(node[SCORE].InnerText),
Date = Convert.ToDateTime(node[DATE].InnerText)
};
list.Add(item); //and add it to the collection
}
return(list); //when finished, return this collection
}
catch (XmlException)
{
//throw an exception if an error occured
throw new Exception("Error occured while reading data.");
}
}
return(new List <PlayerScore>()); //if no XML file exists, return an empty list
}
/// <summary>
/// Creates a new high scores XML file using a collection of PlayerScore objects. If the file already exists, it will be overwritten.
/// This method encrypts the name of the player in the XML file.
/// </summary>
/// <param name="scores">A collection of PlayerScore objects, representing all the high scores needed to be stored</param>
private void SaveScores(List <PlayerScore> scores)
{
try
{
//create the XML file
XmlDocument xmlDoc = new XmlDocument();
XmlTextWriter writer = new XmlTextWriter(FileName, Encoding.UTF8)
{
Formatting = Formatting.Indented
};
writer.WriteProcessingInstruction("xml", "version='1.0' encoding='UTF-8'");
writer.WriteStartElement(SCORES);
writer.Close();
//Blank the file
xmlDoc.PreserveWhitespace = true;
xmlDoc.Load(FileName);
// Create a new RSA key. This key will encrypt a symmetric key,
// which will then be imbedded in the XML document.
CspParameters parameters = new CspParameters
{
KeyContainerName = ConfigurationSettings.AppSettings["ScoresFileEncryptionKey"]
//KeyContainerName = "XML_ENC_RSA_KEY"
};
RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(parameters);
// Decrypt the "Player" element.
TrippleDESDocumentEncryption.Decrypt(xmlDoc, rsaKey, "rsaKey");
//Add each high score to the XML file
foreach (PlayerScore score in scores)
{
//get the main node
XmlNode documentNode = xmlDoc.DocumentElement;
//create a new child node for each high score
XmlElement highScoreChild = xmlDoc.CreateElement(HIGHSCORE);
//create new elements for the name, score and date/time
XmlElement ScoreElement = xmlDoc.CreateElement(SCORE);
XmlElement PlayerElement = xmlDoc.CreateElement(PLAYER);
XmlElement DateElement = xmlDoc.CreateElement(DATE);
XmlText scoreText = xmlDoc.CreateTextNode("score");
XmlText playerText = xmlDoc.CreateTextNode("player");
XmlText dateText = xmlDoc.CreateTextNode("date");
//add the new high score child node to the main node
documentNode.AppendChild(highScoreChild);
//and add all the data to the high score child node
highScoreChild.AppendChild(ScoreElement);
highScoreChild.AppendChild(PlayerElement);
highScoreChild.AppendChild(DateElement);
ScoreElement.AppendChild(scoreText);
PlayerElement.AppendChild(playerText);
DateElement.AppendChild(dateText);
scoreText.Value = score.Score.ToString();
playerText.Value = score.Player;
dateText.Value = score.Date.ToString();
// Encrypt the "Player" element.
TrippleDESDocumentEncryption.Encrypt(xmlDoc, PLAYER, rsaKey, "rsaKey");
}
xmlDoc.Save(FileName); //save the file
}
catch (Exception exception4)
{
}
}
