public void Exersise4()
{
var cipherTexts = File.ReadAllLines(@"FileForSet1_Exercise4.txt");
var solution = new Solution();
var bestResult = new SolveSingleXORKeyResult();
foreach (var line in cipherTexts)
{
var result = solution.SolveSingleXORKey(line);
if (result.Score > bestResult.Score)
{
bestResult = result;
}
}
Assert.Equal("Now that the party is jumping\n", bestResult.PlainText);
}
public SolveSingleXORKeyResult SolveSingleXORKey(IEnumerable <byte> cipherBytes)
{
var result = new SolveSingleXORKeyResult();
for (var key = 1; key < 128; key++)
{
var possibleAnswer = cipherBytes
.Select(b => (char)(b ^ key))
.ConcatStrings();
var numberOfEnglishLetters = possibleAnswer.Count(c => char.IsLetterOrDigit(c) || c == ' ');
if (numberOfEnglishLetters > result.Score)
{
result.Score = numberOfEnglishLetters;
result.PlainText = possibleAnswer;
result.Key = (char)key;
}
}
return(result);
}
