public static bool ConfirmEcbMode(int blockSize)
{
var b = SecureRng.GenerateRandomBytes(blockSize);
var duplicateBlocks = new List <byte>();
duplicateBlocks.AddRange(b);
duplicateBlocks.AddRange(b);
var encrypted = EncryptionOracle(duplicateBlocks.ToArray());
return(AesEcb.IsEcbEncrypted(encrypted, blockSize));
}
public static CipherMode EncryptEcbOrCbc(byte[] data, out CipherMode actualMode)
{
actualMode = Rand.Next(0, 2) == 0 ? CipherMode.ECB : CipherMode.CBC;
var key = SecureRng.GenerateRandomBytes(KeySizeBytes);
// Add prefix and suffix to data
data = TransformData(data);
byte[] encrypted;
if (actualMode == CipherMode.ECB)
{
var padded = PaddingUtil.Pad(data, BlockSizeBytes);
encrypted = AesEcb.Encrypt(key, padded);
}
else
{
var iv = SecureRng.GenerateRandomBytes(BlockSizeBytes);
encrypted = AesCbc.Encrypt(key, iv, data);
}
var guessedMode = AesEcb.IsEcbEncrypted(encrypted, BlockSizeBytes)
? CipherMode.ECB
: CipherMode.CBC;
return(guessedMode);
}
