There was a wonderful analysis of How Robert Galbraith was found to be JK Rowling the other day, and, basically, beyond the anonymous tip, it was the fact that a textual analysis of her work matched her OTHER known work more closely than any other author. This is exactly what I'm talking about when I say the NSA does not need to read your email - we're all leaving EXTREMELY DETAILED digital finger prints ALL THE TIME that identify us, locate us - basically reveal anything that anyone would need to know.