In a first aspect of the invention, method for classifying characters within a character string entered via a keyboard device includes logging interrupts, checking a time between interrupts, checking an interrupt duration and classifying the characters within the character string based upon the time between interrupts and the interrupt duration. In a second aspect of the invention, a method for protecting against timing attacks against a trusted path mechanism includes employing a multithreaded process with a first thread to prevent any timing Trojan horses from running, running the first thread in a loop at a first priority and preventing unprivileged processes from obtaining a priority higher than the first priority.