1. A method of performing an action on a computing device in a manner that is at least partly resistant to modification or analysis, said method comprising: executing on said computing device a first set of computer-executable instructions storable on a computer-readable medium that implements a sub-action, wherein: performance of said action is in at least some way furthered by performance of said sub-action; said action comprises computing results of applying a cryptographic key to first data using attributes of the cryptographic key but without access to, storing in memory, or exposing a whole or segment of the cryptographic key; and executing on said computing device a second set of computer-executable instructions that implements said sub-action, said second set of computer-executable instructions being different from said first set of computer-executable instructions.