With WhatsApp denying that its popular messaging app has a backdoor that allows government agencies to snoop and read our messages, app privacy has once again been called into question.
ESET senior research fellow Nick Fitzgerald says that the WhatsApp saga demonstrates that the company chose ease of use over better security and privacy, but ‘backdooring’ is an overreaction.
He says that Apple’s iMessage made the same tradeoff, but nobody has accused Apple of backdooring.
“In short, the technical issue here is that if the intended recipient of an as-yet-undelivered message changes their WhatsApp installation because they get a new phone, change their SIM, install the app on a previously unused device or uninstall and reinstall the app, their encryption key will change.
“By default, WhatsApp on the sending device will take the original, still-unsent message and re-encrypt it with the new key and try to send that instead. In WhatsApp, there is a setting that can change this behaviour to the ‘more secure’ option, whereby the user of the device with the unsent message is warned that the recipient has changed keys and then asks the user to verify that the change is legitimate.
“Some other apps, including Signal and Wire, default to, or only implement, the optional behaviour in WhatsApp,” he explains.
He says that WhatsApp is one of various messaging apps that use the Signal secure messaging protocol. There are others that change the default to warn the user of a key change, rather than just to continue communicating.
Fitzgerald says that choosing secure messaging apps can be a challenge, but the Electronic Frontier Foundation (EFF) has resources available, including a scorecard to compare security on popular messaging apps.
“The EFF are working on improved metrics for comparing the security of such apps, but in the meantime potential users of such apps may learn something from reading the scorecard.”
Fitzgerald also recommends that users regularly research safe app use and keep to using official messaging apps, rather than unofficial ones that may be less secure.