WhatsApp has begun rolling out its much-anticipated multi-device feature to a select group of beta users, with the feature expected to be broadly available soon. WhatsApp claims it doesn’t have a firm timetable for when the new multi-device feature will be available to all users. If users want to try out the function, they can download the beta version of the app or wait a few months until WhatsApp releases the feature in the stable version of the app. However, it is unclear whether the feature would be available to all Android and iOS beta users.
WhatsApp’s parent company, Facebook, announced in a blog post that users can now use WhatsApp on up to four non-phone devices at the same time, even if their phone battery is dead. “Each companion device will connect to your WhatsApp individually, providing the same level of privacy and security that people who use WhatsApp have come to expect,” Facebook explains.
WhatsApp now requires that a phone be turned on in order to work on other devices. According to the messaging app, this caused challenges for users who wanted to use WhatsApp on different devices because they would have to rely only on their phone’s internet connection or batteries to do so. It also restricted people from being on call in the portal while checking their messages because only one device could be active at a time.
WhatsApp claims that the multi-device functionality will be secure across all of a user’s devices because it uses extended security codes to represent combinations of a user’s device IDs, allowing a sender to verify the devices to which he is sending messages. Because identity verifications can be time-consuming, WhatsApp will introduce Automatic Device Verification, which will allow devices to verify their codes with the recipient just once until the sender completely re-registers his account.
The prior way of linking devices will remain the same: each device will be linked using a QR code from the user’s phone. Where people have activated this functionality on compatible devices, the process will need biometric authentication before joining. Users will be able to view which companion devices are linked to their account and when they were last used after completing all of the procedures, as well as log out of them remotely if necessary.
WhatsApp says its multi-device messaging system would adopt a “client-fanout technique,” in which the WhatsApp client delivering the message encrypts and sends it N times to N separate devices in the sender and receiver’s device lists. It states that each communication is encrypted separately with each device using a pairwise encryption session that has been formed, and that messages are not saved on any server after they have been delivered. The same is true for groupings.
