public DataExchangeKeys ComputeKeys(DHKeyPair my_key_pair, BigInteger buddy_public_key)
{
if (Utility.IsValidPublicKey(buddy_public_key) == false)
throw new ArgumentException("DataExchangeKeysManager:Buddy public key is invalid");
if (my_key_pair == null)
throw new ArgumentException("DataExchangeKeysManager: My Key Pair cannot be null");
if (my_key_pair.GetPrivateKey() < 1)
throw new ArgumentException("DataExchangeKeysManager: Private key in my_key_pair value cannot be less than 0");
if (buddy_public_key < 1)
throw new ArgumentException("DataExchangeKeysManager: Buddy public key value cannot be less than 0");
if (my_key_pair.GetPublicKey() > buddy_public_key)
{
_end_type = OTR_END_TYPE.HIGH_END;
_send_byte = OTRConstants.HIGH_END_SEND_BYTE_VALUE;
_recv_byte = OTRConstants.HIGH_END_RECV_BYTE_VALUE;
}
else
{
_end_type = OTR_END_TYPE.LOW_END;
_send_byte = OTRConstants.LOW_END_SEND_BYTE_VALUE;
_recv_byte = OTRConstants.LOW_END_RECV_BYTE_VALUE;
}
_data_exchange_keys = new DataExchangeKeys();
_data_exchange_keys.SetEndType(_end_type);
_secret = Utility.ComputeSecret(my_key_pair, buddy_public_key, OTRConstants.RFC_3526_GENERATOR, OTRConstants.RFC_3526_PRIME_MODULO());
Utility.SetSecByteMpi(_secret, ref _sec_data_byte_array_mpi);
_data_exchange_keys.SetSecData(_sec_data_byte_array_mpi);
ComputeSendKeys();
ComputeRecvKeys();
ComputeAesExtraKey();
return _data_exchange_keys;
}
private void AddOldMacKeys(DataExchangeKeys old_data_exchange_keys)
{
if (old_data_exchange_keys == null)
return;
_old_rx_mac_keys.Add(old_data_exchange_keys.GetMACKeyRecv());
_old_rx_mac_keys.Add(old_data_exchange_keys.GetMACKeySend());
}
public DataExchangeKeys GetDataExchangeKeys()
{
_data_exchange_keys_holder = _recent_data_exchange_keys;
_recent_data_exchange_keys = _data_exhange_key_manager.
ComputeKeys(_my_recent_dh_key_pair, _my_buddy_recent_dh_public_key);
_counter++;
if (_data_exchange_keys_holder != _recent_data_exchange_keys)
{
_old_data_exchange_keys = _data_exchange_keys_holder;
_data_exchange_keys_holder = null;
AddOldMacKeys(_old_data_exchange_keys);
}
return _recent_data_exchange_keys;
}