[GH-ISSUE #887] Self-signed certificates: Support Trust on first use #692

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opened 2026-02-26 01:31:22 +03:00 by kerem · 0 comments

kerem commented

2026-02-26 01:31:22 +03:00

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Originally created by @Woi on GitHub (Apr 22, 2018).
Original GitHub issue: https://github.com/jberkel/sms-backup-plus/issues/887

Background
There was some discussion in #839, on how to avoid unnoticed man-in-the-middle attacks (MITM) for connections using self-signed certificates. One suggested solution is documented in #875. Another suggestion was "trust on first use" (TOFU).

User Story
As user syncing to a server using a self signed cert, I like to get notified if the cert changes, to avoid unnoticed MITM.

Acceptance criteria

SMS Backup+ shows a warning when connecting to a server which uses a certificate not signed by a trusted CA
The user can chose to trust this cert or abort the connection
The warning contains the necessary information (fingerprint of cert, server name, ...) to allow for an informed decision.
Further connections to the same server succeed silently, if the cert was trusted
If the cert changes to a cert which is not signed by a trusted CA, the same warning is shown as above.

Originally created by @Woi on GitHub (Apr 22, 2018). Original GitHub issue: https://github.com/jberkel/sms-backup-plus/issues/887 **Background** There was some discussion in #839, on how to avoid unnoticed man-in-the-middle attacks (MITM) for connections using self-signed certificates. One suggested solution is documented in #875. Another suggestion was "trust on first use" (TOFU). **User Story** As user syncing to a server using a self signed cert, I like to get notified if the cert changes, to avoid unnoticed MITM. **Acceptance criteria** * SMS Backup+ shows a warning when connecting to a server which uses a certificate not signed by a trusted CA * The user can chose to trust this cert or abort the connection * The warning contains the necessary information (fingerprint of cert, server name, ...) to allow for an informed decision. * Further connections to the same server succeed silently, if the cert was trusted * If the cert changes to a cert which is not signed by a trusted CA, the same warning is shown as above.