Some tips for secure leaking

Investigative reporting's lifeblood is the leak, and ProPublica has published a guide to leaking without getting caught, including high-tech things like cell phone encryption and one low-tech but very secure method — the mail: "U.S. postal mail without a return address is one of the most secure ways to communicate — authorities would need a warrant to intercept and open it in transit. You can mail us paper materials or digital files on, for example, a thumb drive."