public static byte[] Decrypt()
{
// Determine block size of encryption oracle
var blockSize = FindBlockSize();
// Ensure encryption oracle is using ECB mode
if (!ConfirmEcbMode(blockSize))
{
throw new InvalidOperationException("Encryption oracle is not encrypting in ECB mode.");
}
var knownBytes = new List <byte>();
var blockIndex = 0;
while (true)
{
var b = DecryptNextByte(blockSize, knownBytes, blockIndex);
if (b == -1)
{
break;
}
knownBytes.Add((byte)b);
if (knownBytes.Count % blockSize == 0)
{
blockIndex++;
}
}
var unpadded = PaddingUtil.RemovePad(knownBytes.ToArray());
return(unpadded);
}
public static byte[] Decrypt()
{
// Determine block size of encryption oracle
var blockSize = FindBlockSize();
// Determine prefix size of encryption oracle
var prefixSize = FindPrefixSize(blockSize);
var knownBytes = new List <byte>();
var blockIndex = (int)Math.Ceiling((double)prefixSize / blockSize);
while (true)
{
var b = DecryptNextByte(blockSize, prefixSize, knownBytes, blockIndex);
if (b == -1)
{
break;
}
knownBytes.Add((byte)b);
if (knownBytes.Count % blockSize == 0)
{
blockIndex++;
}
}
var unpadded = PaddingUtil.RemovePad(knownBytes.ToArray());
return(unpadded);
}
public static Dictionary <string, string> DecryptProfile(byte[] encrypted)
{
var decrypted = AesEcb.Decrypt(Key, encrypted);
var encoded = PaddingUtil.RemovePad(decrypted);
var decoded = KvpParser.Decode(System.Text.Encoding.ASCII.GetString(encoded));
return(decoded);
}
public void Challenge7()
{
var keyStr = "YELLOW SUBMARINE";
var key = System.Text.Encoding.ASCII.GetBytes(keyStr);
var data = Convert.FromBase64String(Set1Data.Challenge7Input);
var decrypted = AesEcb.Decrypt(key, data);
decrypted = PaddingUtil.RemovePad(decrypted);
var clearText = System.Text.Encoding.ASCII.GetString(decrypted);
Assert.AreEqual(Set1Data.Challenge7Solution, clearText);
}
public static byte[] Decrypt(out int randIndex)
{
var c = EncryptionOracle(out randIndex);
var blocks = c.Chunks(BlockSizeBytes);
blocks.Insert(0, Iv);
var knownBytes = new List <byte>();
for (int i = 0; i < blocks.Count - 1; i++)
{
var previousBlock = blocks[i];
var targetBlock = blocks[i + 1];
var decrypted = Decrypt(targetBlock, previousBlock);
knownBytes.AddRange(decrypted);
}
return(PaddingUtil.RemovePad(knownBytes.ToArray()));
}
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);
}