6 tips to keep your emails secret

If David Petraeus couldn't keep his affair from prying eyes as CIA director, then what chance does an average person have? Experts say people underestimate how transparent digital communications have become.

"Hacking and spying went mainstream a decade ago," said Dan Kaminsky, an internet security researcher. "Everyone is reading everyone else'semails — girlfriends are reading boyfriends' , bosses are reading employees' — because it's just so easy to do."

Know adversaryPetraeus and his biographer , Paula Broadwell, may have thought the threat was their spouses. So, they reportedly did not send emails, but saved messages to the draft folder to avoid leaving a digital trail. But neither took steps to hide their computers' IP addresses.

Hide locationThey could have masked IP addresses using Tor, a popular privacy tool, or used a virtual private network , which adds a layer of security to public Wi-Fi networks.

Go off the recordChoose the "off the record" feature on Google Talk, Google's IM client, which ensures that nothing typed is saved or searchable in either person's Gmail account.

Encrypt messagesEmail encryption services , like GPG, help protect digital secrets from eavesdroppers. Without an encryption key, any message stored in an inbox or reached from the cloud will look like gibberish . Wickr, a mobile app, performs a similar service for phones, encrypting video, photos and text, and erasing deleted files for good.

Set self-destruct timerServices like 10 Minute Mail allow users to open an email address and send a message, and the address self-destructs 10 minutes later. Wickr also allows users to set a self-destruct timer so they can control how long a recipient can view a file before it disappears.

Drop draft ideaSaving emails in a shared draft folder is no safer than transmitting them. They are stored in the cloud. Even if they are deleted, email service providers can be compelled to provide copies.