Secure messaging platform Signal introduces chat backup options

In an age where there is increased concern about privacy and security, people are embracing messaging platforms such as Signal. While Signal and other apps of its ilk mean enjoying a security boost, such apps are playing catch-up with mainstream messaging platforms in terms of other features and options.

Signal has just announced the availability of secure backups for chats, promising an easy way to restore your messaging history to a new device. This is something that Signal users have been begging for, and now it is here. As you might expect with a platform associated with security and privacy, backups are not a simple matter with Signal.

While there is a free backup option available as part of the launch, Signal is also offering another tier with a monthly fee. The free backup option lets you back up 45 days of messages and media (up to 100MiB), while the paid-for option will back up everything until you hit a limit of 100 GB. The cost is $1.99 per month, although Signal says that this could change.

The company also points out:

This is the first time we’ve offered a paid feature. The reason we’re doing this is simple: media requires a lot of storage, and storing and transferring large amounts of data is expensive. As a nonprofit that refuses to collect or sell your data, Signal needs to cover those costs differently than other tech organizations that offer similar products but support themselves by selling ads and monetizing data.

Backups are opt-in; Signal is well-aware that although the feature is much-requested, not everyone wants to back up their messaging history – and may have a very good reason not to do so. The company explains how the security of backups and subscription payments is maintained:

Using the same zero-knowledge technology that enables Signal groups to work without revealing intimate metadata, backup archives are stored without a direct link to a specific backup payment or Signal user account.

At the core of secure backups is a 64-character recovery key that is generated on your device. This key is yours and yours alone; it is never shared with Signal’s servers. Your recovery key is the only way to “unlock” your backup when you need to restore access to your messages. Losing it means losing access to your backup permanently, and Signal cannot help you recover it. You can generate a new key if you choose. We recommend storing this key securely (writing it down in a notebook or a secure password manager, for example).

Backing up Signal

Signal provides important notes about how the backup process works:

Once you’ve enabled secure backups, your device will automatically create a fresh secure backup archive every day, replacing the previous day’s archive. Only you can decrypt your backup archive, which will allow you to restore your message database (excluding view-once messages and messages scheduled to disappear within the next 24 hours). Because your secure backup archive is refreshed daily, anything you deleted in the past 24 hours, or any messages set to disappear are removed from the latest daily secure backup archive, as you intended.

Security is hugely important, and double encryption is used at times: “We have also taken extra steps to protect media by encrypting the already-encrypted files a second time with a key unique to your backup and adding padding to obscure their true size. This prevents malicious actors from comparing encrypted files to identify users who are in the same groups, in the unlikely instance that they gain access to the backup files”. 

For now, the backup options are available in the latest beta version of Signal for Android, but there are plans to bring then to iOS and the desktop at some point in the future. Further plans for the future include introducing the ability to move messaging history between platforms.