Signal has extended its encrypted backup capability to iOS and desktop applications, completing an initial cross-platform rollout that now covers Android, iOS, Windows, macOS, and Linux.
The feature is included in Signal version 8.30. It is designed to help users recover conversations and attachments after losing or replacing a phone, while keeping backup contents protected with end-to-end encryption.
Hosted and local backup choices
Users can choose between backups stored by Signal and files retained locally on their own devices or storage media. Local backups do not have a stated size cap, but users must protect their recovery key. Signal said that the same local-backup recovery key can decrypt historical archives created with it, making secure storage of that key particularly important.
Signal-hosted backups have different limits depending on the plan. Free accounts can retain up to 45 days of media and have a per-message limit of 128 KB, while paid plans provide up to 100 GB of storage. In addition to the recovery key, hosted backups use a supplementary key that rotates daily within a Trusted Execution Environment, according to Signal.
Changes to transfers and media handling
The update also standardizes Android backups around the format used across the newly supported platforms. When a user links a new device, Signal can retrieve older attachments that are not already present in the conversation history.
Media files are now handled separately from the main backup archive, and duplicate items are stored once rather than copied repeatedly. Subscribers can also remove older full-resolution media from local storage while retaining thumbnails, with the app retrieving complete files from hosted backups when needed.
Messages configured to disappear within 24 hours are excluded from both local and hosted backups. Signal noted that restoring a local archive will also skip disappearing messages whose retention period has already expired. Creating a hosted backup does not remove any existing local backup files.
For iPhone users, version 8.30 adds direct device-to-device migration over an end-to-end encrypted Wi-Fi Aware connection. Signal said the local transfer method is intended to improve the speed and reliability of moving data between iPhones.
The company described the release as the completion of the first phase of its backup project and said engineering efforts will next shift toward improvements outside the backup system.