static void Main(string[] args)
{
// Variables
string hexEncodedStr = "1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736";
ScoredMessage[] decodedTopFiveResults = new ScoredMessage[5];
// Populate decodedTopFiveResults
for (int i = 0; i < decodedTopFiveResults.Length; i++)
{
decodedTopFiveResults[i] = new ScoredMessage();
}
// Pass hexEncodedStr to DiscoverSingleCharacterKey object for decoding
DiscoverSingleCharacterKey key = new DiscoverSingleCharacterKey(hexEncodedStr);
// Get top five decoded results
decodedTopFiveResults = key.getTopFive();
// Display top five decoded results
for (int i = 0; i < decodedTopFiveResults.Length; i++)
{
Console.WriteLine(decodedTopFiveResults[i].ToString());
}
}
/// <summary>
/// Orders decoded messages by their scores and selects
/// top five most likely candidates based on character
/// frequency.
/// </summary>
/// <returns>array of top 5 scored messages</returns>
public ScoredMessage[] getTopFive()
{
// Initialize ScoredMessage object topFive
ScoredMessage[] topFive = new ScoredMessage[5];
ArrayList msgArray = new ArrayList();
int index = 25;
// Add objects from scoredMessages to msgArray
foreach (ScoredMessage value in scoredMessages)
{
msgArray.Add(value);
}
// Sort message array.
msgArray.Sort();
// Populate top five ScoredMessage array.
for (int i = 0; i < topFive.Length; i++)
{
topFive[i] = (ScoredMessage)msgArray[index];
index--;
}
return(topFive);
}
public int CompareTo(object obj)
{
if (obj is ScoredMessage)
{
ScoredMessage sMsg = (ScoredMessage)obj;
return(Score.CompareTo(sMsg.Score));
}
else
{
throw new NotImplementedException();
}
}
/// <summary>
/// Default constructor for DiscoverSingleCharacterKey
/// class. Takes in message as argument.
/// </summary>
/// <param name="message"></param>
public DiscoverSingleCharacterKey(string message)
{
this.message = message;
//assign values to the array
for (int i = 0; i < scoredMessages.Length; i++)
{
scoredMessages[i] = new ScoredMessage();
}
twoDigitHexValueSeperation = separateHexValueIntoPairs(message);
decodeXORMessage();
}
/// <summary>
/// Decodes the XOR'd hex string against each letter in the
/// alphabet.
/// </summary>
/// <param name="letterRawByte">Raw byte representation of letter</param>
/// <param name="key">char representation of letter</param>
/// <returns>Scored Message object with decoded data</returns>
private ScoredMessage decodeXORCalc(string letterRawByte, char key)
{
//Local variables
string[] decodedByte = new string[rawByteHexPair.Length];
string decodedMessage = "";
ScoredMessage sMsg = new ScoredMessage();
// loop through each hexPair and decode message with single
// char from alphabet.
for (int i = 0; i < rawByteHexPair.Length; i++)
{
int decodedDecimal = 0;
for (int j = 0; j < 8; j++)
{
// If the encoded bit is 1 the decoded bit is the opposite
// of the letter bit.
if (rawByteHexPair[i].ElementAt(j) == '1')
{
if (letterRawByte.ElementAt(j) == '1')
{
decodedByte[i] += "0";
}
else
{
decodedByte[i] += "1";
}
}
// If the encoded bit is 0 the decoded bit is the same as
// the letter bit.
else
{
decodedByte[i] += letterRawByte.ElementAt(j);
}
}
// Convert decoded byte to string and add to decoded message.
decodedDecimal = Convert.ToInt32((decodedByte[i]), 2);
decodedMessage += Convert.ToChar(decodedDecimal);
}
// Populate ScoredMessage obj
sMsg.Message = decodedMessage;
sMsg.Score = score.scoreMessage(decodedMessage);
sMsg.Key = key;
return(sMsg);
}
