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Signal Adds Encrypted Local Backups on iPhone, Windows, macOS, and Linux
Here’s some good news for Signal users: the app can now back up your conversations to an external drive or NAS, all with end-to-end encryption. Let’s take a closer look at this new feature.
A little over a year ago, I introduced Secure Backups, Signal’s cloud backup feature for messages and media. It first arrived on Android, with two options: a free plan that backs up text messages and protects only media received within the last 45 days, and a paid plan that offers up to 100 GB of media storage.
However, Secure Backups relied on cloud storage, which does not appeal to everyone. That has now changed with the release of Signal 8.30 and one major new feature: local backups directly on the device are arriving on iPhone and on Signal Desktop, meaning Windows, macOS, and Linux. On Android, they have existed for years, but they have been completely redesigned.
More importantly, Signal now offers a cross-platform approach to restoring data from a backup, whether that backup is hosted by Signal or stored locally. In other words, moving from an Android smartphone to an iPhone without losing your message history is now possible. About time.
Local backups: what changes with the new Signal
With a local backup, you choose the destination: device storage, an external drive, a NAS on your local network, or even a third-party storage service. The data remains end-to-end encrypted and, because it is local, there is no size limit.
- A common format: the old Android local backup stored everything in a single archive. Now, media is stored in a separate folder and duplicate files are kept only once.
- Ephemeral messages excluded: messages set to disappear within 24 hours are not backed up, regardless of the selected mode. Those that expire in the meantime are ignored when restoring a local backup.
- Reworked iPhone transfer: migrating from an old iPhone to a new one now uses a local, encrypted, end-to-end wireless link based on Wi-Fi Aware.
Signal also includes a storage optimization feature. When enabled, old photos and videos are replaced by a thumbnail on the device, while the original remains in the backup. This can save a huge amount of local storage space. "For example, 5,120 megabytes (that is, 5 GB) of unused media space now take up only about 600 megabytes once the “Optimize Signal Storage” setting is enabled, leaving you much more room to receive new images and videos.", Signal explains. However, this feature seems to be reserved for the paid plan.
Another addition: Signal Desktop can now retrieve an encrypted copy of a missing attachment from your smartphone with a single click. This is handy on a computer that has just been linked to the Signal account, and it relies on the linked devices feature that German police also abuse to read the WhatsApp, Signal, and Telegram messages of their targets.
The recovery key: the weak point
Whatever mode you choose, your backups are protected by the recovery key. Cloud backups benefit from enhanced security in the form of a second key that is renewed every day and stored in a trusted execution environment (TEE). Useless without the recovery key, it provides the main layer of confidentiality. In other words, an old backup becomes unreadable once that second key is replaced, even if you still have the recovery key.
This mechanism does not exist for local backups, because Signal must adapt to any storage medium. As a result, the local recovery key decrypts all older backups, wherever they are stored, and not just the most recent one. "Some will see these as limitations; we see them as necessary trade-offs for real-world deployment", Signal says.
The Signal recovery key has already attracted cybercriminals. On June 26, 2026, the FBI and CISA warned about a phishing campaign attributed to Russian intelligence services (UNC5792 and UNC4221) in which this key was targeted. Attackers impersonate Signal support, push victims to enable backups, and then to paste their recovery key into the conversation. With it, they can access message history and decrypt backups that have already been recovered, even if the user generates a new key.
What do you think?
