Signal has released version 8.30, completing the deployment of its end-to-end encrypted backup feature across Android, iOS, Linux, macOS, and Windows. First introduced on Android, the system now provides iOS and desktop users with native options to archive and restore chat histories across devices.
Unified Formats and Storage Optimization
The latest release revamps Android backups and aligns them with iOS and desktop applications under a shared cross-platform format. Media files are now isolated from the central backup archive, and duplicate files are stored only once to prevent redundant sync operations. When linking a new device, the added client can retrieve missing older attachments from the primary device.
Signal offers two archiving paths: Signal-hosted backups and local, on-device backups. Hosted backups restrict free tiers to 45 days of media and 128 KB per message, whereas local backups carry no size limits. Paid subscribers gain an option to offload full local media to hosted storage while retaining local thumbnails. For direct iPhone-to-iPhone transfers, version 8.30 leverages an encrypted Wi-Fi Aware connection to speed up migrations.
Security Keys and Excluded Content
Both hosted and local options are encrypted using a recovery key. Hosted archives additionally utilize daily rotating keys inside a Trusted Execution Environment to preserve forward secrecy. However, a single local recovery key can decrypt any past local backup file created with it, leading threat actors to target these keys shortly after the initial feature rollout.
The backup system intentionally excludes disappearing messages set to expire within 24 hours. Additionally, restoring from local archives automatically skips expired ephemeral messages. Signal noted that this release completes the initial phase of its multi-platform backup initiative.
AI-generated editorial illustration; not a documentary photograph.
Source: Signal adds encypted local backup support to iOS, desktop apps
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