So to defeat this you just write a higher current salary on your application, right?
It won't stop all places, but it will stop some places. You have to be OK with that.
I'd never assume that your salary is a secret. It's pretty easy to figure it out. Making a material misstatement about it will be perceived as a character defect at best if you are caught, which may happen in the future when you are in some stupid internal dispute.