public static bool IsAdmin(byte[] data)
{
var decrypted = AesCbc.Decrypt(Key, Iv, data);
var str = System.Text.Encoding.ASCII.GetString(decrypted);
return(str.Contains(";admin=true;"));
}
public static byte[] EncryptionOracle(out int randIndex)
{
var r = new Random();
randIndex = r.Next(0, Data.Length);
var input = Data[randIndex];
return(AesCbc.Encrypt(Key, Iv, Convert.FromBase64String(input)));
}
public static byte[] EncryptionOracle(string input)
{
var encoded = input.Replace(";", "%3B").Replace("=", "%3D");
var b1 = System.Text.Encoding.ASCII.GetBytes(Prefix);
var b2 = System.Text.Encoding.ASCII.GetBytes(Suffix);
var bytes = new List <byte>();
bytes.AddRange(b1);
bytes.AddRange(System.Text.Encoding.ASCII.GetBytes(encoded));
bytes.AddRange(b2);
return(AesCbc.Encrypt(Key, Iv, bytes.ToArray()));
}
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);
}
public static bool IsValid(byte[] data)
{
var decryted = AesCbc.Decrypt(Key, Iv, data, false);
return(PaddingUtil.ValidPadding(decryted, BlockSizeBytes));
}
