public byte[] EncodeEncryptedMessage(IMessage message, byte[] authKey, ulong salt, ulong sessionId, Sender sender)
{
Argument.IsNotNull(() => authKey);
Argument.IsNotNull(() => message);
ulong authKeyId = ComputeAuthKeyId(authKey);
byte[] serBody = _tlRig.Serialize(message.Body, TLSerializationMode.Boxed);
int serBodyLength = serBody.Length;
int innerDataLength = EncryptedInnerHeaderLength + serBodyLength;
int mod = innerDataLength % Alignment;
int paddingLength = mod > 0 ? Alignment - mod : 0;
_randomGenerator.FillWithRandom(_alignmentBuffer);
int innerDataWithPaddingLength = innerDataLength + paddingLength;
int length = EncryptedOuterHeaderLength + innerDataWithPaddingLength;
// Writing inner data.
var innerDataWithPadding = new byte[innerDataWithPaddingLength];
using (var streamer = new TLStreamer(innerDataWithPadding))
{
streamer.WriteUInt64(salt);
streamer.WriteUInt64(sessionId);
streamer.WriteUInt64(message.MsgId);
streamer.WriteUInt32(message.Seqno);
streamer.WriteInt32(serBodyLength);
streamer.Write(serBody);
streamer.Write(_alignmentBuffer, 0, paddingLength);
}
Int128 msgKey = ComputeMsgKey(new ArraySegment <byte>(innerDataWithPadding, 0, innerDataLength));
// Encrypting.
byte[] aesKey, aesIV;
ComputeAesKeyAndIV(authKey, msgKey, out aesKey, out aesIV, sender);
byte[] encryptedData = _encryptionServices.Aes256IgeEncrypt(innerDataWithPadding, aesKey, aesIV);
Debug.Assert(encryptedData.Length == innerDataWithPaddingLength, "Wrong encrypted data length.");
var messageBytes = new byte[length];
using (var streamer = new TLStreamer(messageBytes))
{
// Writing header.
streamer.WriteUInt64(authKeyId);
streamer.WriteInt128(msgKey);
// Writing encrypted data.
streamer.Write(encryptedData, 0, innerDataWithPaddingLength);
}
return(messageBytes);
}