RC4 doesn't have any shifts; I think you must be thinking of another algorithm. What it does have is data-dependent loads, which are also undesirable. Edit: I

RC4 doesn't have any shifts; I think you must be thinking of another algorithm. What it does have is data-dependent loads, which are also undesirable. Edit: I think you were probably thinking of RC5. That one does have data-dependent shifts. It's never been in wide use, though.