WhatsApp has finally started rolling out the much-awaited multi-device capability that will allow users to access the instant messaging app not just on their phones but also on up to four non-phone devices at the same time. The new development, that is initially a limited public beta test, comes months after the rumour mill suggested its behind-the-scenes existence. WhatsApp says that it “had to rethink” its architecture and design new systems to bring multi-device support to its final shape. The Facebook-owned company is also claimed to preserve its privacy and end-to-end encryption while enabling the new experience.
Although WhatsApp has been allowing users to access its platform simultaneously on a secondary device such as a desktop or laptop for some time, the latest update is meant to provide a standalone multi-device experience in which users don't even need their phones to be connected to the Internet or could even be switched off. This is helpful in many cases.
So, for instance, even if your phone's battery is dead, you will still be able to access WhatsApp on your laptop using the new multi-device capability. This will also come into picture if the Internet connection on your phone is unstable but you have a stable network connected to your desktop.
WhatsApp has been working on the multi-device capability for the last several months — some references suggested its progress since July 2019. The company says that it developed new technologies to maintain end-to-end encryption while keeping your data such as message history, contact names, and starred messages in sync seamlessly across devices.
“WhatsApp multi-device uses a client-fanout approach, where the WhatsApp client sending the message encrypts and transmits it N number of times to N number of different devices — those in the sender and receiver's device lists,” the firm explained in a detailed post. “Each message is individually encrypted using the established pairwise encryption session with each device. Messages are not stored on the server after they are delivered.”
Alongside messages, WhatsApp has retained its end-to-end encryption for voice and video calls available on multiple devices. The company also says that it syncs data such as message history and application state data including contact names and whether a chat is archived or if a message is starred across devices. The data that is synced between devices is also claimed to be end-to-end encrypted.
WhatsApp has updated its security whitepaper to detail how it implemented multi-device support while retaining the same level of encryption that it offers on individual devices.
“Beginning on July 14, 2021, a user can have multiple devices, each with its own set of encryption keys. If the encryption keys of one device are compromised, an attacker cannot use them to decrypt the messages sent to other devices, even devices registered to the same user,” the company said in its whitepaper.
How to get WhatsApp multi-device capability
WhatsApp has initially made its multi-device capability available to a “small group of users” who are already a part of its beta programme. However, there are plans to add opt-in beta access even for users on a stable version that will be available through the Linked devices screen in the coming future.
Users who are getting the multi-device capability on their WhatsApp account will be able to link new companion devices by scanning a QR code from their phone. This is identical to how you can connect your account on WhatsApp Web or desktop today. You will also be asked for biometric authentication before linking. Further, at any point of time, you will have the ability to log out from a companion device or see all the devices linked to your account and when they were last used.
By bringing extensive support for multiple devices, WhatsApp has made it easier for users to access its messaging platform through the Web, macOS, Windows, and even devices like Facebook Portal. The timing of the new update is also interesting as people are currently working remotely and spending more time on their computing devices (say a desktop or laptop) over phones.
WhatsApp has also been anticipated to bring native support for iPad. While it seems to still be in the works and not yet ready for the users, the multi-device capability could work as a substitute for the time being even on the iPad.
It is important to point out that similar to WhatsApp, Apple's iMessage has provided multi-device support exclusively on Apple devices for quite some time. Telegram also has support for multiple devices, but that's not available with end-to-end encryption and is limited to cloud chats — not for syncing its secret chats. Signal, on the other hand, allows users to access the service on their desktop (or up to 5 linked devices) but requires them to connect via a phone for sending and receiving messages.