public void Challenge2()
{
var a = new HexString("1c0111001f010100061a024b53535009181c");
var b = new HexString("686974207468652062756c6c277320657965");
var expected = "746865206b696420646f6e277420706c6179";
var xord = XorUtil.Xor(a.Bytes.ToArray(), b.Bytes.ToArray());
var actual = new HexString(xord).ToString();
Assert.AreEqual(expected, actual);
}
public byte CrackKey(HexString hexString)
{
var scores = new Dictionary <byte, TextScore>();
for (int key = 1; key < 127; key++)
{
var decrypted = XorUtil.Xor(hexString.Bytes.ToArray(), new[] { (byte)key });
var plainText = System.Text.Encoding.ASCII.GetString(decrypted);
scores.Add((byte)key, _textScoreCalculator.CalculateScore(plainText));
}
var ordered = scores.OrderByDescending(x => x.Value.Score);
return(ordered.First().Key);
}
public void Challenge3()
{
string input = "1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736";
var expectedKey = (byte)88;
var expectedString = "Cooking MC's like a pound of bacon";
var hexString = new HexString(input);
var decryptor = new SingleByteXorCracker(new BigramCalculator());
var actualKey = decryptor.CrackKey(hexString);
var decryptedBytes = XorUtil.Xor(hexString.Bytes.ToArray(), new[] { actualKey });
var actualString = System.Text.Encoding.ASCII.GetString(decryptedBytes);
Assert.AreEqual(expectedKey, actualKey);
Assert.AreEqual(expectedString, actualString);
}
public void Callenge6()
{
var expectedString = "";//Set1Data.Challenge6Solution;
var expectedKey = System.Text.Encoding.ASCII.GetBytes("Terminator X: Bring the noise");
var input = Set1Data.Challenge6Input.Replace("\r\n", string.Empty);
var encryptedData = Convert.FromBase64String(input);
var singleByteCracker = new SingleByteXorCracker(new BigramCalculator());
var cracker = new MultiByteXorCracker(singleByteCracker);
var actualKey = cracker.CrackKey(encryptedData);
var decryptedData = XorUtil.Xor(encryptedData, actualKey);
var actualString = System.Text.Encoding.ASCII.GetString(decryptedData);
Assert.AreEqual(expectedString, actualString);
Assert.AreEqual(expectedKey, actualKey);
}
public void Challenge5()
{
var input =
"Burning 'em, if you ain't quick and nimble\nI go crazy when I hear a cymbal";
var key = "ICE";
var expected =
"0b3637272a2b2e63622c2e69692a23693a2a3c6324202d623d63343c2a26226324272765272a282b2f20430a652e2c652a3124333a653e2b2027630c692b20283165286326302e27282f";
var inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
var keyBytes = System.Text.Encoding.ASCII.GetBytes(key);
var expectedHexString = new HexString(expected);
var actualBytes = XorUtil.Xor(inputBytes, keyBytes);
var actualHexString = new HexString(actualBytes);
CollectionAssert.AreEqual(expectedHexString.Bytes.ToArray(), actualBytes);
Assert.AreEqual(expectedHexString.ToString(), actualHexString.ToString());
}
public static byte[] Encrypt(byte[] key, byte[] nonce, byte[] data)
{
ulong counter = 0;
var keyStream = new byte[BlockSizeBytes];
var blocks = data.Chunks(BlockSizeBytes);
var xord = new List <byte>(data.Length);
foreach (var block in blocks)
{
var counterBytes = BitConverter.GetBytes(counter);
Array.Copy(nonce, keyStream, nonce.Length);
Array.Copy(counterBytes, 0, keyStream, nonce.Length, counterBytes.Length);
var blockKey = AesEcb.Encrypt(key, keyStream);
xord.AddRange(XorUtil.Xor(block, blockKey));
counter++;
}
return(xord.ToArray());
}
public void Challenge4()
{
var expectedString = "Now that the party is jumping\n";
var expectedKey = 53;
var strings = Set1Data.Challenge4Input.Split(new[]
{
'\n', '\r'
}, StringSplitOptions.RemoveEmptyEntries);
var hexStrings = strings.Select(s => new HexString(s)).ToArray();
ITextScoreCalculator textScoreCalculator = new BigramCalculator();
var cracker = new SingleByteXorCracker(textScoreCalculator);
int index;
var actualKey = cracker.CrackKey(hexStrings, out index);
var decrytedBytes = XorUtil.Xor(hexStrings[index].Bytes.ToArray(), new[] { actualKey });
var actualString = System.Text.Encoding.ASCII.GetString(decrytedBytes);
Assert.AreEqual(expectedString, actualString);
Assert.AreEqual(expectedKey, actualKey);
}
public static byte[] Decrypt(byte[] key, byte[] iv, byte[] data, bool removePadding = true)
{
var blocks = data.Chunks(BlockSizeBytes);
var clearText = new byte[data.Length];
int index = 0;
var previousBlock = iv;
foreach (var block in blocks)
{
var blockArray = block.ToArray();
var decrypted = AesEcb.Decrypt(key, blockArray);
var xord = XorUtil.Xor(decrypted, previousBlock);
Array.Copy(xord, 0, clearText, index, BlockSizeBytes);
previousBlock = blockArray;
index += BlockSizeBytes;
}
if (removePadding)
{
return(PaddingUtil.RemovePad(clearText));
}
return(clearText);
}
public static byte[] Encrypt(byte[] key, byte[] iv, byte[] data)
{
int paddingLength = BlockSizeBytes - (data.Length % BlockSizeBytes);
paddingLength = paddingLength == 0 ? BlockSizeBytes : paddingLength;
int cipherTextLength = data.Length + paddingLength;
var cipherText = new byte[cipherTextLength];
var paddedData = PaddingUtil.Pad(data, BlockSizeBytes);
var blocks = paddedData.Chunks(BlockSizeBytes);
int index = 0;
var previousBlock = iv;
foreach (var block in blocks)
{
var xord = XorUtil.Xor(block.ToArray(), previousBlock);
var encrypted = AesEcb.Encrypt(key, xord);
Array.Copy(encrypted, 0, cipherText, index, BlockSizeBytes);
previousBlock = encrypted;
index += BlockSizeBytes;
}
return(cipherText);
}
public byte CrackKey(HexString[] hexStrings, out int index)
{
int currentMax = 0;
index = -1;
byte bestKey = 0;
for (int i = 0; i < hexStrings.Length; i++)
{
var hexString = hexStrings[i];
var key = CrackKey(hexString);
var decrypted = XorUtil.Xor(hexString.Bytes.ToArray(), new[] { key });
var plainText = System.Text.Encoding.ASCII.GetString(decrypted);
var score = _textScoreCalculator.CalculateScore(plainText);
if (score.Score > currentMax)
{
currentMax = score.Score;
bestKey = key;
index = i;
}
}
return(bestKey);
}
