WhatsApp, one of the most popular messaging programs in the world, is now testing the most requested feature: multi-device support.
Currently, the app can only be used on one device, which is usually your phone. To communicate with your friends and family, you can use the web client or the desktop program, but your phone must be connected to the internet.
The company stated last month that it is working on a feature that will allow users to attach four devices to a single account. As long as you're connected to the internet, you can use each device individually.
WhatsApp announced last night that the feature is being sent out to a select group of users. It also explained how it intends to introduce the feature while maintaining your privacy.
What is the most difficult aspect of secure multi-device communication?
It's not uncommon to have many devices linked to a chat app account. Telegram, for example, makes use of its cloud to let you utilize the software on numerous devices at once. These communications, however, are not safeguarded by end-to-end encryption, which is a key feature of WhatsApp.
WhatsApp currently generates keys for end-to-end encryption using your phone. Your desktop clients are merely reflections of that. That strategy is ineffective for multi-device communication. As a result, WhatsApp must save safe combinations of identities from all of your connected devices.
Furthermore, the business claims to have invented a technique called Automatic Device Verification, which it claims will automatically validate your associated devices when sending messages. You had to scan a QR code to link a device — usually your desktop client — to your phone's WhatsApp account till today. However, you'll need to provide biometric verification for the multi-device function.
How does WhatsApp want to make secure communication easier with its multi-device features?
It's simple to build an encrypted channel and have the desktop client rely on it when there's only one source device. When you have many devices attached to a single account, however, the design must adapt. WhatsApp will establish numerous encrypted channels of two types when this capability is available: from your source to other devices and from your source to the sender's device.
WhatsApp will send a message to a server before sending it to a friend. Through several end-to-end encrypted secure routes, that server will transmit the message to all of your devices for synchronizing, as well as to your friend. According to the company, the server does not save any of your messages.
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| WhatsApp’s new multi-device feature |
The source of truth in WhatsApp's previous architecture was a smartphone. However, with WhatsApp's new multi-device capabilities, up to four additional non-phone companion devices can connect to the service independently while preserving the same level of privacy and security.
WhatsApp will send your message to the linked devices and to your friend through an intermediary server.
The software intends to employ a technique called Secure Real-time Transport Protocol to secure calls (SRTP). When you make a call, the 32-bit SRTP master secret keys are sent to all of your friend's connected devices. When your friend receives a call from one of these devices, the SRTP master key generated for that device is used to establish a secure connection.
The new technology, according to the business, also allows you to keep track of your messages across devices that are all protected by end-to-end encryption. It hasn't been started when this function will be available to the general public, but we'll keep an eye on it.