wxz123

Don't do it that way, that's a very bad idea. Write the entire 64-bit number to the buffer.

Big thanks, on 4 step i've got a buffer for request: 146A5F50F269A90E02000000 and noticed that F269A90E (Int32: 245983730) doesn't change on ClientMicroTxnAuthorize and txn_id (on GCStorePurchaseInitResponse) equal to orderid, but still I didn't get the response after request, I'm using node-steam
var payload = new ByteBuffer(0, ByteBuffer.LITTLE_ENDIAN); payload.writeUInt32(data.transID.toInt()); // data.transID.toInt() == 1144076083 payload.append('F269A90E02000000', 'hex'); // == 371DB34FF269A90E02000000 steamClient.send({ msg: EMsg.ClientMicroTxnAuthorize, proto: {} }, payload.buffer);