private void CloseOTRSession(string session_closed_message)
{
DebugPrint("Ending OTR session");
_otr_event_args = new OTREventArgs();
_otr_event_args.SetMessage(session_closed_message);
_otr_event_args.SetOTREvent(OTR_EVENT.CLOSED);
DoOTREvent(_otr_event_args);
_message_state = OTR_MESSAGE_STATE.MSG_STATE_PLAINTEXT;
_message_manager = null;
_ake_keys_manager = null;
_dsa_signer = null;
_signature_manager = null;
_smp_manager = null;
_ake_keys = null;
_my_unique_id = string.Empty;
_my_buddy_unique_id = string.Empty;
_otr_fragment_object = null;
EndSMPSession();
}
private void ProcessDataMessage(OTRMessage otr_message)
{
DebugPrint("Received Data Message");
if (_message_state != OTR_MESSAGE_STATE.MSG_STATE_ENCRYPTED)
{
OTRError("ProcessDataMessage: OTR Engine is not in the MSG_STATE_ENCRYPTED state",
"ProcessDataMessage: OTR Engine is not in the MSG_STATE_ENCRYPTED state",
null);
return;
}
/*Compute new keys */
DataExchangeKeys _data_exchange_keys = _otr_session_object.GetDataExchangeKeys(otr_message.GetRecipientKeyId(),
_otr_message.GetSenderKeyId(), _otr_message.GetNextDHPublicKeyMpi(), _re_key_my_dh_keys);
string _error_string = null;
if (_data_exchange_keys == null)
{
if (otr_message.GetFlags() != OTRConstants.IGNORE_UNREADABLE)
_error_string = "You transmitted an unreadable encrypted message";
OTRError("ProcessDataMessage: Data exchange keys are null",
"ProcessDataMessage: Data exchange keys are null",
_error_string);
return;
}
/* Compute hash with MAC receiving key */
_temp_buffer = Utility.SHA1GetKeyedHash(_data_exchange_keys.GetMACKeyRecv(), otr_message.GetBytesToAuthenticate());
/* Compare hashed MAC */
if (Utility.IsArrayEqual(_temp_buffer, otr_message.GetAuthenticationMAC()) == false)
{
if (otr_message.GetFlags() != OTRConstants.IGNORE_UNREADABLE)
_error_string = "You transmitted an unreadable encrypted message";
OTRError("Message MAC authentication failed", "Message MAC authentication failed", _error_string);
return;
}
/* Decrypt message data */
try
{
_temp_buffer = Utility.AESGetDecrypt(_data_exchange_keys.GetAESKeyRecv(),
otr_message.GetEncryptedData(), otr_message.GetCounterTopHalf());
_extra_symmetric_key_temp = _data_exchange_keys.GetAESKeyExtra();
}
catch (Exception ex)
{
if (otr_message.GetFlags() != OTRConstants.IGNORE_UNREADABLE)
_error_string = "You transmitted an unreadable encrypted message";
else
_error_string = string.Empty;
OTRError("ProcessDataMessage:Unable to decrypte message",
"ProcessDataMessage:" + ex.ToString(),
_error_string);
_otr_fragment_object = null;
return;
}
/* Process plain text */
if (_otr_fragment_object != null)
{
_otr_fragment_object.ClearCombinedString();
_otr_fragment_object = null;
}
ProcessPlaintext(_temp_buffer,_otr_message.GetOldMacKeys());
}
private void ProcessOTRFragment(string otr_fragment_string)
{
if (_otr_fragment_object == null)
_otr_fragment_object = new OTRFragmentObject();
string _string_1 = string.Empty;
string _string_2 = string.Empty;
string[] _parts = null;
_string_1 = otr_fragment_string.Substring(4, otr_fragment_string.Length - 5);
if (_current_otr_version != OTR_VERSION.VERSION_2)
{
if (_string_1.Substring(0, 1).Equals("|") == false)
{
OTRError("ProcessOTRFragment:Fragment not properly formatted", null, null);
return;
}
_string_1 = _string_1.Substring(1, _string_1.Length - 1);
_parts = _string_1.Split(new char[] { '|' }, 2);
UInt32 _sender_instance_tag = Convert.ToUInt32(_parts[0].Trim());
if (_sender_instance_tag != _message_manager.GetBuddyIntanceTag())
{
OTRError("ProcessOTRFragment:Invalid sender instance tag", null, null);
return;
}
_parts = _parts[1].Split(new char[] { ',' }, 2);
UInt32 _receiver_instance_tag = Convert.ToUInt32(_parts[0].Trim());
if (_receiver_instance_tag != _message_manager.GetMyIntanceTag())
{
OTRError("ProcessOTRFragment:Invalid receiver instance tag", null, null);
return;
}
}
else
_parts = _string_1.Split(new char[] { ',' }, 2);
_parts = _parts[1].Split(new char[] { ',' }, 2);
UInt16 _fragment_number = Convert.ToUInt16(_parts[0].Trim());
_parts = _parts[1].Split(new char[] { ',' }, 2);
UInt16 _total_number_fragments = Convert.ToUInt16(_parts[0].Trim());
DebugPrint("Received fragment " + _fragment_number.ToString() + " of " + _total_number_fragments.ToString());
if (_otr_fragment_object.IsSetFragment(_parts[1], _fragment_number, _total_number_fragments) == false)
{
OTRError("ProcessOTRFragment:Fragment number " + _fragment_number.ToString() + " of " + _total_number_fragments.ToString() + " was discarded", null, null);
return;
}
if (_fragment_number == _total_number_fragments)
ProcessOTRMessage(_otr_fragment_object.GetCombinedString());
}