private static EncryptResult EncryptMessage(ThreemaMessage threemaMessage, byte[] privateKey, byte[] publicKey)
{
// determine random amount of PKCS7 padding
int padbytes = new Random().Next(254) + 1;
byte[] messageBytes;
try
{
messageBytes = threemaMessage.GetData();
}
catch
{
return(null);
}
// prepend type byte (0x02) to message data
byte[] data = new byte[1 + messageBytes.Length + padbytes];
data[0] = (byte)threemaMessage.GetTypeCode();
messageBytes.CopyTo(data, 1);
// append padding
for (int i = 0; i < padbytes; i++)
{
data[i + 1 + messageBytes.Length] = (byte)padbytes;
}
return(Encrypt(data, privateKey, publicKey));
}
public bool MessageCallback([FromForm] ThreemaMessageCallback threemaMessageCallback)
{
try
{
try
{
_log.LogDebug("ThreemaController.MessageCallback: ModelState {0}, ThreemaMessageCallback {1}", ModelState.IsValid, threemaMessageCallback.ToString());
}
catch (Exception ex)
{
_log.LogError("ThreemaController.MessageCallback 1 " + ex.Message);
}
string nonce = threemaMessageCallback.Nonce;
string box = threemaMessageCallback.Box;
string callbackPublicKey = GetPublicKey(threemaMessageCallback.From);
string myPrivateKey = this._configuration["Threema:PrivateKey"];
Key privateKey = Key.DecodeKey(myPrivateKey);
Key publicKey = Key.DecodeKey(callbackPublicKey);
ThreemaMessage message = CryptTool.DecryptMessage(
DataUtils.HexStringToByteArray(box),
privateKey.key,
publicKey.key,
DataUtils.HexStringToByteArray(nonce)
);
switch (message.GetTypeCode())
{
case TextMessage.TYPE_CODE:
_log.LogInformation("ThreemaController.MessageCallback TextMessage from {0} to {1}: {2}", threemaMessageCallback.From, threemaMessageCallback.To, message.ToString());
break;
//case DeliveryReceipt.TYPE_CODE:
//class DeliveryReceipt statt public class DeliveryReceipt
case 0x80:
_log.LogInformation("ThreemaController.MessageCallback DeliveryReceipt from {0} to {1}: {2}", threemaMessageCallback.From, threemaMessageCallback.To, message.ToString());
break;
default:
_log.LogInformation("ThreemaController.MessageCallback ThreemaMessage? from {0} to {1}: {2}", threemaMessageCallback.From, threemaMessageCallback.To, message.ToString());
break;
}
return(true);
}
catch (Exception ex)
{
_log.LogError("ThreemaController.MessageCallback 2 " + ex.Message);
return(false);
}
}
/// <summary>
/// Wrapper to decrypt box <see cref="Threema.MsgApi.CryptTool.DecryptMessage"/>
/// </summary>
/// <param name="box">Encrypted box as hex-straing</param>
/// <param name="recipientPrivateKey">Recipient private key as hex-string</param>
/// <param name="senderPublicKey">Sender public key as hex-string</param>
/// <param name="nonce">Nonce as hex-string</param>
/// <returns>Array with type and decrypted message</returns>
public ArrayList DecryptMessage(string box, string recipientPrivateKey, string senderPublicKey, string nonce)
{
byte[] privateKey = GetKey(recipientPrivateKey, Key.KeyType.PRIVATE);
byte[] publicKey = GetKey(senderPublicKey, Key.KeyType.PUBLIC);
byte[] nonceBytes = DataUtils.HexStringToByteArray(nonce);
byte[] boxBytes = DataUtils.HexStringToByteArray(box);
ThreemaMessage message = CryptTool.DecryptMessage(boxBytes, privateKey, publicKey, nonceBytes);
var result = new ArrayList();
result.Add(message.GetTypeCode().ToString());
result.Add(message.ToString());
return(result);
}