internal static void XorEncryptAndWrite(Stream output, int size, byte[] data, byte[] key1, byte[] iv1, byte[] key2, byte[] iv2)
{
byte[] rpad = RandomHelper.GenerateBytes(size);
byte[] xor = new byte[size];
for (int i = 0; i < size; i++)
{
xor[i] = (byte)(data[i] ^ rpad[i]);
}
byte[] d1 = ChaCha20Rfc7539.Encrypt(rpad, key1, iv1);
byte[] d2 = AES.EncryptCBC(xor, key2, iv2);
BinaryHelper.WriteLV(output, d1);
BinaryHelper.WriteLV(output, d2);
}
/// <summary>
/// Decrypt with RSA key
/// </summary>
/// <param name="input">Input stream</param>
/// <param name="output">Output stream</param>
/// <param name="rsa">RSA key</param>
/// <param name="notifyProgression">Notify progression method</param>
public static void DecryptWithKey(Stream input, Stream output, RSACryptoServiceProvider rsa, Action <int> notifyProgression = null)
{
input.Seek(5, SeekOrigin.Current); // Header
input.Seek(1, SeekOrigin.Current); // Version
byte[] keyNameData = BinaryHelper.ReadLV(input);
byte[] encKeysData = BinaryHelper.ReadLV(input);
if (notifyProgression != null)
{
notifyProgression(5 + 1 + 2 * 4 + keyNameData.Length + encKeysData.Length);
}
byte[] keysData = RSA.Decrypt(rsa, encKeysData);
byte[] key1, iv1, key2, iv2;
using (MemoryStream ms = new MemoryStream(keysData))
{
key1 = BinaryHelper.ReadLV(ms);
iv1 = BinaryHelper.ReadLV(ms);
key2 = BinaryHelper.ReadLV(ms);
iv2 = BinaryHelper.ReadLV(ms);
}
byte[] d1, d2;
byte[] backup = null;
do
{
d1 = BinaryHelper.ReadLV(input);
if (d1.Length > 0)
{
if (backup != null)
{
output.Write(backup, 0, backup.Length);
}
byte[] rpad = ChaCha20Rfc7539.Decrypt(d1, key1, iv1);
d2 = BinaryHelper.ReadLV(input);
byte[] xor = AES.DecryptCBC(d2, key2, iv2);
if (notifyProgression != null)
{
notifyProgression(2 * 4 + d1.Length + d2.Length);
}
byte[] data = new byte[rpad.Length];
for (int i = 0; i < rpad.Length; i++)
{
data[i] = (byte)(rpad[i] ^ xor[i]);
}
backup = new byte[data.Length];
Array.Copy(data, 0, backup, 0, data.Length);
}
else
{
byte[] unpadData = Padding.Unpad(backup, AES.BLOCK_SIZE, _paddingStyle);
output.Write(unpadData, 0, unpadData.Length);
}
} while (d1.Length > 0);
}
