Add Yahoo as a preferred source to see more of our stories on Google. William Abel, a mail censor at Iowa's State Prison, Fort Madison, using a hot iron to bring out a secret message written in lemon ...

Vlogger Reuben Levine tells the story of the Colombian army in 2010 sending a message to prisoners of a revolutionary guerilla group by hiding a Morse code message in a concocted pop song. Watch this ...

Secret messages can be hidden inside fake conversations generated by AI chatbots. The technique could give people a way to communicate online without arousing the suspicion of oppressive governments.