Larry Flynt, a defender of free speech and sexual freedom if there ever was one, has this advice for anyone worried by the hack of infidelity site Ashley Madison: Muzzle yourself.

"Don't do or say anything you wouldn't want to read about on the front page of the New York Times," said the founder of Hustler magazine and owner of businesses that sell sexually explicit videos online.

It might be too late for many people who, lured by a supposed cloak of digital anonymity, have shared their innermost wishes, fetishes and fantasies on hook-up and porn sites. And those companies know that their digital troves of secrets are exactly what make them a target for emboldened hackers.