public void StartOTRSession(string otr_version_string)
{
OTR_VERSION _otr_version = Utility.GetOTRVersion(otr_version_string);
if (_otr_version == OTR_VERSION.INVALID)
throw new ArgumentException("StartOTRSession:The OTR Version is unsupported or invalid");
SetOTRVersion(_otr_version);
_aes_key = Utility.GetRandomByteArray(OTRConstants.AES_KEY_LENGTH_BITS / 8);
byte[] _dh_commit_message = _message_manager.FormatDHCommit(_otr_session_object.GetMyRecentDHKeyPair().GetDHPublicKeyData(_aes_key, _otr_session_object.GetCounter()));
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_AWAITING_DH_KEY;
DebugPrint("Sending DH Commit Message");
SendOTRMessage(_dh_commit_message);
}
private void ProcessSignatureMessage(OTRMessage otr_message)
{
DebugPrint("Received Signature Message");
_otr_event_args = new OTREventArgs();
if (_authentication_state != OTR_AUTH_STATE.AUTH_STATE_AWAITING_SIG)
{
OTRError("ProcessSignatureMessage: OTR Engine is not in the AUTH_STATE_AWAITING_SIG state",
"ProcessSignatureMessage: OTR Engine is not in the AUTH_STATE_AWAITING_SIG state",
null);
return;
}
if (otr_message.GetEncodedEncryptedSignature() == null || otr_message.GetEncodedEncryptedSignature().Length < 1)
{
OTRError("ProcessSignatureMessage: The encoded encrypted signature byte array cannot be null/empty", null,
"OTR Failed. Unexpected error");
return;
}
if (otr_message.GetMacDSignature() == null || otr_message.GetMacDSignature().Length < 1)
{
OTRError("ProcessSignatureMessage: The MAC'd signature byte array cannot be null/empty", null,
"OTR Failed. Unexpected error");
return;
}
_otr_event_args.SetOTREvent(OTR_EVENT.ERROR);
byte[] dsa_public_key_byte_array_encoded = null;
bool _is_sig_verified = SignatureManager.IsSignatureVerified(_ake_keys, _otr_session_object.GetMyRecentDHKeyPair(), _otr_session_object.GetBuddyRecentPublicKeyMpi(),
otr_message.GetEncodedEncryptedSignature(), otr_message.GetMacDSignature(), false, ref _temp_int_32_val, ref dsa_public_key_byte_array_encoded);
if (_otr_session_object.IsComputeBuddyFingerPrint(dsa_public_key_byte_array_encoded) == false)
{
OTRError("ProcessSignatureMessage:" + _my_buddy_unique_id + "'s DSA public key fingerprint computation failed",
"ProcessSignatureMessage:" + _my_buddy_unique_id + "'s DSA public key fingerprint computation failed",
null);
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_NONE;
return;
}
if (_is_sig_verified != true)
{
OTRError("ProcessSignatureMessage:" + _my_buddy_unique_id + "'s signature verification failed",
"ProcessSignatureMessage:" + _my_buddy_unique_id + "'s signature verification failed",
null);
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_NONE;
return;
}
/* Inform client of OTR readiness */
_otr_session_object.SetFirstBuddyPublicKeyID(_temp_int_32_val);
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_NONE;
_message_state = OTR_MESSAGE_STATE.MSG_STATE_ENCRYPTED;
_otr_event_args.SetOTREvent(OTR_EVENT.READY);
_otr_event_args.SetMessage(_my_buddy_unique_id + "'s signature verification successful");
DoOTREvent(_otr_event_args);
}
private void ProcessDHKeyMessage(OTRMessage otr_message)
{
DebugPrint("Received DH Key Message");
_otr_event_args = new OTREventArgs();
if (_authentication_state != OTR_AUTH_STATE.AUTH_STATE_AWAITING_DH_KEY)
{
OTRError("ProcessDHKeyMessage: OTR Engine is not in the AUTH_STATE_AWAITING_DH_KEY state", "ProcessDHKeyMessage: OTR Engine is not in the AUTH_STATE_AWAITING_DH_KEY state",
null);
return;
}
if (otr_message.GetGxMpi() == null || otr_message.GetGxMpi().Length < 1)
{
OTRError("ProcessDHKeyMessage: The received MPI encoded public key byte array cannot be null/empty", null,
"OTR Failed. Unexpected error");
return;
}
if (_otr_session_object.IsSetBuddyFirstPublicKey(otr_message.GetGxMpi()) == false)
{
OTRError("ProcessDHKeyMessage:" + _my_buddy_unique_id + "'s DH public key is invalid",
"ProcessDHKeyMessage:" + _my_buddy_unique_id + "'s DH public key is invalid",
"OTR Failed. Unexpected error");
return;
}
_ake_keys = _ake_keys_manager.ComputeKeys(_otr_session_object.GetMyRecentDHKeyPair(), _otr_session_object.GetBuddyRecentPublicKey());
_signature_manager.ComputeSignature(_ake_keys, _otr_session_object.GetMyRecentDHKeyPair().GetPublicKeyMpiBytes(), _otr_session_object.GetMyRecentDHKeyPair().GetKeyIDBytes(),
otr_message.GetGxMpi(), _otr_session_object.GetCounter(), true);
if (_aes_key == null || _aes_key.Length < 1)
{
OTRError("ProcessDHKeyMessage: The AES key byte array cannot be null/empty", null,
"OTR Failed. Unexpected error");
return;
}
Utility.EncodeOTRDataBE(_aes_key, ref _temp_buffer);
_temp_buffer_2 = new byte[_temp_buffer.Length + _signature_manager.GetSignatureDataLength()];
Buffer.BlockCopy(_temp_buffer, 0, _temp_buffer_2, 0, _temp_buffer.Length);
Buffer.BlockCopy(_signature_manager.GetSignatureDataBytes(), 0, _temp_buffer_2, _temp_buffer.Length, _signature_manager.GetSignatureDataLength());
byte[] _dh_reveal_byte_array = _message_manager.FormatRevealSig(_temp_buffer_2);
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_AWAITING_SIG;
DebugPrint("Sending Reveal Signature Message");
SendOTRMessage(_dh_reveal_byte_array);
}
private void ProcessRevealSigMessage(OTRMessage otr_message)
{
DebugPrint("Received Reveal Signature Message");
_otr_event_args = new OTREventArgs();
if (_authentication_state != OTR_AUTH_STATE.AUTH_STATE_AWAITING_REVEAL_SIG)
{
OTRError("ProcessRevealSigMessage: OTR Engine is not in the AUTH_STATE_AWAITING_REVEAL_SIG state",
"ProcessRevealSigMessage: OTR Engine is not in the AUTH_STATE_AWAITING_REVEAL_SIG state",
null);
return;
}
if (otr_message.GetRevealedKey() == null || otr_message.GetRevealedKey().Length < 1)
{
OTRError("ProcessRevealSigMessage: The AES revealed key byte array cannot be null/empty", null,
"OTR Failed. Unexpected error");
return;
}
if (otr_message.GetEncodedEncryptedSignature() == null || otr_message.GetEncodedEncryptedSignature().Length < 1)
{
OTRError("ProcessRevealSigMessage: The encoded encrypted signature byte array cannot be null/empty", null,
"OTR Failed. Unexpected error");
return;
}
if (otr_message.GetMacDSignature() == null || otr_message.GetMacDSignature().Length < 1)
{
OTRError("ProcessRevealSigMessage: The MAC'd signature byte array cannot be null/empty", null,
"OTR Failed. Unexpected error");
return;
}
_otr_event_args.SetOTREvent(OTR_EVENT.ERROR);
if (_dh_commit_message == null || _dh_commit_message.GetEncryptedGxMpi() == null || _dh_commit_message.GetEncryptedGxMpi().Length < 1)
{
OTRError("ProcessRevealSigMessage: The MPI encoded encrypted public key (g^x mpi) should not be null/empty",
"ProcessRevealSigMessage: The MPI encoded encrypted public key (g^x mpi) should not be null/empty",
"OTR Failed. Unexpected error");
return;
}
if (_otr_session_object.IsSetMyBuddyFirstPublicKey(otr_message.GetRevealedKey(), _dh_commit_message.GetEncryptedGxMpi(),
_dh_commit_message.GetHashedGxMpi()) == false)
{
OTRError("ProcessRevealSigMessage: The MPI encoded decrypted public key (g^x mpi) should not be null/empty",
"ProcessRevealSigMessage: The MPI encoded decrypted public key (g^x mpi) should not be null/empty",
"OTR Failed. Unexpected error");
return;
}
_ake_keys = _ake_keys_manager.ComputeKeys(_otr_session_object.GetMyRecentDHKeyPair(), _otr_session_object.GetBuddyRecentPublicKey());
byte[] dsa_public_key_byte_array_encoded = null;
bool _is_sig_verified = SignatureManager.IsSignatureVerified(_ake_keys, _otr_session_object.GetMyRecentDHKeyPair(), _otr_session_object.GetBuddyRecentPublicKeyMpi(),
otr_message.GetEncodedEncryptedSignature(), otr_message.GetMacDSignature(), true, ref _temp_int_32_val, ref dsa_public_key_byte_array_encoded);
if (_otr_session_object.IsComputeBuddyFingerPrint(dsa_public_key_byte_array_encoded) == false)
{
OTRError("ProcessRevealSigMessage:" + _my_buddy_unique_id + "'s DSA public key fingerprint computation failed",
"ProcessRevealSigMessage:" + _my_buddy_unique_id + "'s DSA public key fingerprint computation failed",
null);
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_NONE;
return;
}
if (_is_sig_verified != true)
{
OTRError("ProcessRevealSigMessage:" + _my_buddy_unique_id + "'s signature verification failed",
"ProcessRevealSigMessage:" + _my_buddy_unique_id + "'s signature verification failed",
"OTR Failed. Unexpected error");
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_NONE;
return;
}
_signature_manager.ComputeSignature(_ake_keys, _otr_session_object.GetMyRecentDHKeyPair().GetPublicKeyMpiBytes(), _otr_session_object.GetMyRecentDHKeyPair().GetKeyIDBytes(),
_otr_session_object.GetBuddyRecentPublicKeyMpi(), _otr_session_object.GetCounter(), false);
//Send signature message
byte[] _dh_signature_byte_array = _message_manager.FormatSignature(_signature_manager.GetSignatureDataBytes());
DebugPrint("Sending Signature Message");
SendOTRMessage(_dh_signature_byte_array);
/* Inform client of OTR readiness */
_otr_session_object.SetFirstBuddyPublicKeyID(_temp_int_32_val);
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_NONE;
_message_state = OTR_MESSAGE_STATE.MSG_STATE_ENCRYPTED;
_otr_event_args.SetOTREvent(OTR_EVENT.READY);
_otr_event_args.SetMessage(_my_buddy_unique_id + "'s signature verification successful");
DoOTREvent(_otr_event_args);
}
private void ProcessDHCommitMessage(OTRMessage otr_message)
{
DebugPrint("Received DH Commit Message");
if (_authentication_state != OTR_AUTH_STATE.AUTH_STATE_NONE)
{
OTRError("ProcessDHCommitMessage: OTR Engine is not in the AUTH_STATE_NONE state", "ProcessDHCommitMessage: OTR Engine is not in the AUTH_STATE_NONE state",
null);
return;
}
_dh_commit_message = otr_message;
byte[] _dh_key_message = _message_manager.FormatDHKey(_otr_session_object.GetMyRecentDHKeyPair().GetPublicKeyMpiBytes());
_authentication_state = OTR_AUTH_STATE.AUTH_STATE_AWAITING_REVEAL_SIG;
DebugPrint("Sending DH Key Message");
SendOTRMessage(_dh_key_message);
}
