How strong is the encryption? Would you be able to protect your strategy if it were distributed? Does the strategy need to be applied to a chart? Can someone just open the chart and see the entries and exits? Or can you just have everything run in the background?
The efs has to be applied to a chart object, although you can code it to not show any study data on the chart itself. Anyone running a backtest of the efs, if it includes entry/exit logic, will be able to determine the prices at which the system would have executed, as well as if they were market, limit, stop orders, but that's not enough to reverse-engineer a system. As far as strength of the encryption? No idea.
I'm assuming it 128 bit encryption. Which is difficult to crack but not impossible. If there is money to be made out of cracking it, someone will come up with a way to crack it.