Windows.COPYDATASTRUCT GetEncryptedMasterKeyTransmission()
{
byte[] encryptedMessage;
byte[] iv;
using (SecureBytesWrapper sbwKey = new SecureBytesWrapper(App.Settings.PasswordMasterKey, true))
{
Encrypt(sbwKey.Bytes, out encryptedMessage, out iv);
}
Windows.COPYDATASTRUCT cds = new Windows.COPYDATASTRUCT();
cds.cbData = sizeof(int) + iv.Length + encryptedMessage.Length;
byte[] combinedMessage = new byte[cds.cbData];
byte[] lengthBytes = BitConverter.GetBytes(iv.Length);
Buffer.BlockCopy(lengthBytes, 0, combinedMessage, 0, lengthBytes.Length);
Buffer.BlockCopy(iv, 0, combinedMessage, lengthBytes.Length, iv.Length);
Buffer.BlockCopy(encryptedMessage, 0, combinedMessage, lengthBytes.Length + iv.Length, encryptedMessage.Length);
cds.lpData = Marshal.AllocHGlobal(cds.cbData);
Marshal.Copy(combinedMessage, 0, cds.lpData, combinedMessage.Length);
cds.dwData = new IntPtr(11);
// caller needs to Marshal.FreeHGlobal(cds.lpData);
return(cds);
}
public void ReceiveEncryptedMasterKeyTransmission(Windows.COPYDATASTRUCT cds)
{
byte[] combinedMessage = new byte[cds.cbData];
Marshal.Copy(cds.lpData, combinedMessage, 0, cds.cbData);
int ivLength = BitConverter.ToInt32(combinedMessage, 0);
// validate length...
if (ivLength > cds.cbData)
{
// throw exception .. ?
throw new ApplicationException("Master Key transmission failed: Initialization Vector received incorrectly");
}
byte[] iv = new byte[ivLength];
Buffer.BlockCopy(combinedMessage, sizeof(int), iv, 0, ivLength);
byte[] encryptedMessage = new byte[cds.cbData - (ivLength + sizeof(int))];
Buffer.BlockCopy(combinedMessage, sizeof(int) + ivLength, encryptedMessage, 0, encryptedMessage.Length);
using (SecureBytesWrapper sbw = new SecureBytesWrapper())
{
Decrypt(encryptedMessage, iv, sbw);
if (!App.Settings.TryPasswordMasterKey(sbw.Bytes))
{
throw new ApplicationException("Master Key transmission failed: Master Key received incorrectly");
}
}
}
public void Decrypt(byte[] encryptedMessage, byte[] iv, SecureBytesWrapper decryptedMessage)
{
using (Aes aes = new AesCryptoServiceProvider())
{
aes.Key = LocalPrivateKey.Bytes;
aes.IV = iv;
// Encrypt the message
using (MemoryStream ciphertext = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ciphertext, aes.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(encryptedMessage, 0, encryptedMessage.Length);
cs.Close();
decryptedMessage.CopyBytes(ciphertext.ToArray());
}
}
}
}
public Session(IntPtr window, System.Diagnostics.Process process)
{
RemoteWindow = window;
Process = process;
process.Exited += process_Exited;
DH = new ECDiffieHellmanCng();
DH.KeyDerivationFunction = ECDiffieHellmanKeyDerivationFunction.Hash;
DH.HashAlgorithm = CngAlgorithm.Sha256;
LocalPublicKey = new SecureBytesWrapper()
{
Bytes = DH.PublicKey.ToByteArray()
};
// this is generated using the remote public key, which we dont have yet
LocalPrivateKey = new SecureBytesWrapper();
}
/// <summary>
/// Initialize with byte array via the SecureStringWrapper, but possibly convert from hex string...
/// </summary>
/// <param name="ssw"></param>
/// <param name="convertFromHex"></param>
public SecureBytesWrapper(SecureStringWrapper ssw, bool convertFromHex)
{
if (!convertFromHex)
{
CopyBytes(ssw.ToByteArray());
return;
}
if (_hexTable == null)
{
_hexTable = new byte[256];
_hexTable['0'] = 0;
_hexTable['1'] = 1;
_hexTable['2'] = 2;
_hexTable['3'] = 3;
_hexTable['4'] = 4;
_hexTable['5'] = 5;
_hexTable['6'] = 6;
_hexTable['7'] = 7;
_hexTable['8'] = 8;
_hexTable['9'] = 9;
_hexTable['a'] = 10;
_hexTable['b'] = 11;
_hexTable['c'] = 12;
_hexTable['d'] = 13;
_hexTable['e'] = 14;
_hexTable['f'] = 15;
}
using (SecureBytesWrapper temp = new SecureBytesWrapper(ssw, false))
{
_Bytes = new byte[temp.Bytes.Length / 2];
for (int i = 0; i < temp.Bytes.Length; i += 2)
{
byte b1 = temp.Bytes[i];
byte b2 = temp.Bytes[i + 1];
_Bytes[i / 2] = (byte)((_hexTable[b1] * 16) + _hexTable[b2]);
}
}
}
