How I can create a smart asset which can be traded only by the asset's issuer? I'm using RIDE language

Question

I am trying to write a smart asset for waves blockchain using RIDE and trying to understand how can I create an asset which can be traded only with issuer. At the same time I’d like to validate sell and buy orders separated in some cases. Now I tried contract like below, but it doesn’t work:

let me = Address(base58'fg4h23j13g4h2j1g4')
match tx {
  case t : ExchangeTransaction => 
         t.sellOrder.sender == me || t.buyOrder.sender == me
...

How does matcher validate orders in case above?