Encryption consistency issues with untrusted devices

Description of the issue

I have set up three Syncthing instances: One running on my laptop (v1.16.1 on ArchLinux), one running on my Android smartphone (Syncthing-Fork v1.16.0.3 from Google Play) and another one on a server based on Syncthing’s Docker image.

The instance running on a server is marked as untrusted and I have set up passwords for all folders shared with it (for Syncthing-Fork I had to go through the Web-UI to do this). All folders are set up as “Receive Encrypted” on the server instance.

This worked successfully for a few hours, but recently I started getting the following message on the server instance:

Failure checking encryption consistency with device pixel5.DOMAIN for folder “Keepass” (keepass): folder is configured to be encrypted but not announced thus

Reproduction Steps

This might turn out to be difficult due to the fact that everything seems to work fine for a while until the encryption property is suddenly dropped.

Version Information

• App Version: 1.16.0.3
• Syncthing Version: v1.16.0 (app), v1.16.1 (Linux)
• Android Version: Android 11
• Device manufacturer: Google
• Device model: Pixel 5

Device platform info

[ro.product.board]: [redfin]
[ro.product.brand]: [google]
[ro.product.build.date]: [Fri Apr  2 19:16:07 UTC 2021]
[ro.product.build.date.utc]: [1617390967]
[ro.product.build.fingerprint]: [google/redfin/redfin:11/RQ2A.210505.003/7255357:user/release-keys]
[ro.product.build.id]: [RQ2A.210505.003]
[ro.product.build.tags]: [release-keys]
[ro.product.build.type]: [user]
[ro.product.build.version.incremental]: [7255357]
[ro.product.build.version.release]: [11]
[ro.product.build.version.release_or_codename]: [11]
[ro.product.build.version.sdk]: [30]
[ro.product.cpu.abi]: [arm64-v8a]
[ro.product.cpu.abilist]: [arm64-v8a,armeabi-v7a,armeabi]
[ro.product.cpu.abilist32]: [armeabi-v7a,armeabi]
[ro.product.cpu.abilist64]: [arm64-v8a]
[ro.product.device]: [redfin]
[ro.product.first_api_level]: [30]
[ro.product.locale]: [en-US]
[ro.product.manufacturer]: [Google]
[ro.product.model]: [Pixel 5]
[ro.product.name]: [redfin]
[ro.product.odm.brand]: [google]
[ro.product.odm.device]: [redfin]
[ro.product.odm.manufacturer]: [Google]
[ro.product.odm.model]: [Pixel 5]
[ro.product.odm.name]: [redfin]
[ro.product.product.brand]: [google]
[ro.product.product.device]: [redfin]
[ro.product.product.manufacturer]: [Google]
[ro.product.product.model]: [Pixel 5]
[ro.product.product.name]: [redfin]
[ro.product.system.brand]: [google]
[ro.product.system.device]: [generic]
[ro.product.system.manufacturer]: [Google]
[ro.product.system.model]: [mainline]
[ro.product.system.name]: [mainline]
[ro.product.system_ext.brand]: [google]
[ro.product.system_ext.device]: [redfin]
[ro.product.system_ext.manufacturer]: [Google]
[ro.product.system_ext.model]: [Pixel 5]
[ro.product.system_ext.name]: [redfin]
[ro.product.vendor.brand]: [google]
[ro.product.vendor.device]: [redfin]
[ro.product.vendor.manufacturer]: [Google]
[ro.product.vendor.model]: [Pixel 5]
[ro.product.vendor.name]: [redfin]
[ro.product.vndk.version]: [30]

Android Log

[Catfriend1]

Thanks, seems like I need to still do this sometime when possible.

[nunesgh]

Hi @Catfriend1!

I can confirm that changes to a folder using the Android UI instead of the Web UI is what causes all encrypted folders to have their passwords erased in Syncthing-Fork.

I have a configuration similar to the following one. Dotted lines are E2EE. All folders in safe devices have two E2EE shares with unsafe devices and one normal share with a safe device. Unsafe devices also share their encrypted folders between them.

I updated Folder 2 in Syncthing-Fork (ST-F) using the Android UI to add an Ignore Pattern to it. As a result, passwords for Folder 1 and Folder 2 were erased from ST-F and I had to re-add the passwords through the Web UI to restore E2EE sync with the unsafe devices.

Otherwise, the setup has been working as expected if no changes are made in ST-F through the Android UI.

Thank you for your attention.