WhatsApp chats already have end-to-end encryption, but what about your online backups? They'll soon be covered, too. As The Verge notes, WABetaInfo has discovered that the latest WhatsApp beta for Android (188.8.131.52) includes a test for end-to-end encrypted cloud backups. Opt in and you don't have to worry that hackers or spies will easily read your conversation history.
There are some caveats. You'll need to create a separate password for restoring your backups, and you can't get them back if you both lose your phone and forget that password. You can alternately create a 64-digit encryption key, but you're also in trouble if you lose that key.
It's not certain that WhatsApp will deploy secure cloud backups with the next stable release, so you might not want to count on it in the near future. It's also unclear if everyone using the new beta gets the same backup functionality.
The timing is apt, at least. WhatsApp just started testing multi-device syncing that isn't dependent on a phone connection. These encrypted backups don't appear to be available across devices, but they could prove reassuring as people depend more and more on WhatsApp for chats on all their gadgets.