Sync: Write & verify device_info via dev settings by CDRussell · Pull Request #9369 · duckduckgo/Android

CDRussell · 2026-07-31T16:46:55Z

Task/Issue URL: https://app.asana.com/1/137249556945/project/608920331025315/task/1217068100697970?focus=true
Tech Design URL (if applicable):
API Proposals URL(s) (if applicable):

Description

Dev-only plumbing for the unified device list's device_info capability. Accessible only from Sync Dev Settings screen for now.

Steps to test this PR

Rename via device_info PATCH works

Fresh install internal build
Open Sync Dev Settings, and tap Create account to quickly sign into sync
Tap Create & Register account_info Key button
Tap Rename device (PATCH device_info) button. Call it test and verify it shows PATCH ok with the chosen name
Tap Fetch & decrypt devices and verify both legacy and device_info has name=test

#### 2nd device confirmation

Install on a 2nd device, and sync with the first device
Visit production Sync & Backup screen and verify you see test as the other device's name

Note

High Risk
Touches sync cryptography, protected key unwrap, and server-side device identity; incorrect encryption or PATCH semantics could break cross-device names or leak mishandled key material paths.

Overview
Adds the unified device list write path: when this device’s name changes, the client encrypts a cross-credential device_info JWE (under the cached account_info public key) and still encrypts legacy name/type for older clients, then PATCHes /sync/devices with all three fields every time (the server clears info if omitted).

New sync-impl pieces include AccountInfoPrivateKeyProvider (unwrap account_info private key for decrypt), DeviceInfoEncryptor/DeviceInfoDecryptor (RSA-OAEP JWE round-trip with a decrypt session), DeviceFieldEncryptor (mirror of existing field decrypt), and DeviceInfoUpdater orchestrating the PATCH. DeviceV2 gains an info field; SyncJweCrypto adds rsaSpkiFromJwkComponents for JWK→SPKI encryption. SyncGzipInterceptor skips gzip on PATCH /sync/devices until the backend accepts it.

Sync Dev Settings exposes rename (dialog → PATCH) and fetch & decrypt devices (legacy vs device_info side by side). Unit tests cover the new encrypt/decrypt/update and remote PATCH behavior.

^{Reviewed by Cursor Bugbot for commit 71bcd4a. Configure here.}

CDRussell · 2026-07-31T16:47:10Z

Add sync feature flags for unified device list #9380
Sync: Write & verify device_info via dev settings #9369 👈 (View in Graphite)
Sync: Extract shared crypto/transport helpers #9360
develop

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CDRussell · 2026-07-31T16:48:23Z

+        // The /sync/devices endpoint rejects gzip bodies as invalid_json, so skip compression here until the backend supports it.
+        val isDevicesEndpoint = chain.request().url.encodedPath.endsWith("/sync/devices")
+
        // check if it's http operation is PATCH
-        if (chain.request().method == "PATCH" && syncFeature.gzipPatchRequests().isEnabled()) {
+        if (chain.request().method == "PATCH" && !isDevicesEndpoint && syncFeature.gzipPatchRequests().isEnabled()) {


This is temporary; should be able to remove this soon as backend will soon support it

CDRussell · 2026-07-31T16:51:43Z

+    fun openSession(): Result<Session>
+
+    /** Decrypts `device_info` blobs with a private key held only for this session's lifetime. */
+    interface Session {


Adding Session as a performance improvement instead of doing a GET network call for every device, instead it can be done once and that will last to get all the devices decrypted.

A better solution is to cache this so a network call isn't needed at all. Will confirm this is possible and do that in a later branch if so.

Dev-only plumbing for the cross-credential device_info blob, exercised from the internal Sync dev-settings screen. No production wiring, no feature flag. - DeviceInfoEncryptor/Decryptor: JWE of {name,type} under the account_info key (RSA-OAEP-256 + A256GCM). SyncJweCrypto.rsaSpkiFromJwkComponents bridges the cached JWK public key to the SPKI form the encrypter wants. - DeviceFieldEncryptor: legacy per-credential name/type encryption (the inverse of DeviceFieldDecryptor) so clients that don't read device_info yet still see the new name. - AccountInfoPrivateKeyProvider: fetch and cache the unwrapped account_info private key for decryption. - DeviceInfoUpdater + PATCH /sync/devices transport (patchThisDevice). - SyncGzipInterceptor: skip gzip for /sync/devices (backend rejects it). - Dev settings: rename-device (PATCH device_info) and fetch/decrypt-devices buttons, plus tests for the non-UI units.

MiSikora · 2026-08-04T05:46:09Z

+    val type: String,
+)
+
+@SingleInstanceIn(AppScope::class)


I've noticed some stateless classes in this PR are marked with @SingleInstanceIn while others aren't, even though there isn't an obvious cost to creating them. This class is one example, and RealDeviceInfoDecryptor is another that goes the opposite way. Is there a convention or reasoning we're following for when to apply @SingleInstanceIn?

Good observation on the inconsistency.

Looking again, it's being applied here when it isn't needed, and in a few other of these related classes too. Unless there's shared state in the class, it's guarding access around a shared resource, or there is a real cost for construction, it's probably not needing to be a singleton.

Will remove it from a few of these classes.

CDRussell · 2026-08-04T09:04:57Z

Merge activity

Aug 4, 9:04 AM UTC: @CDRussell merged this pull request with Graphite.

…pports it (#9405) Task/Issue URL: https://app.asana.com/1/137249556945/project/72649045549333/task/1217193238272991?focus=true Tech Design URL (if applicable): API Proposals URL(s) (if applicable): ### Description The backend now accepts gzipped `PATCH` bodies on `/sync/devices`. When we [first integrated](#9369) with this endpoint `gzip` wasn't supported, so `SyncGzipInterceptor` explicitly skipped compression for it. This removes that exclusion so devices `PATCH` requests are compressed like every other sync `PATCH`. ### Steps to test this PR - QA optional  --- > [!NOTE] > **Medium Risk** > Changes how device PATCH payloads are sent to the sync API; compression failures still fall back to the uncompressed request via existing error handling. > > **Overview** > **`SyncGzipInterceptor`** no longer skips gzip for PATCH requests to **`/sync/devices`**. Those calls now follow the same rule as other sync PATCH traffic when **`gzipPatchRequests`** is enabled. > > The workaround for backend **`invalid_json`** on gzipped device PATCH bodies is removed, along with the **`isDevicesEndpoint`** check and related comment. > > <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit 40717bc. Configure [here](https://www.cursor.com/dashboard/bugbot).</sup>

CDRussell mentioned this pull request Jul 31, 2026

Sync: Extract shared crypto/transport helpers #9360

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CDRussell commented Jul 31, 2026

View reviewed changes

CDRussell force-pushed the feature/craig/sync_unified_device_list_device_info_patch branch 2 times, most recently from 2a7c6f2 to 05dde12 Compare July 31, 2026 16:53

Base automatically changed from feature/craig/sync_unified_device_list_crypto_transport_refactors to develop August 3, 2026 09:19

CDRussell force-pushed the feature/craig/sync_unified_device_list_device_info_patch branch from 05dde12 to 71bcd4a Compare August 3, 2026 15:34

CDRussell marked this pull request as ready for review August 3, 2026 15:48

CDRussell assigned MiSikora Aug 3, 2026

CDRussell mentioned this pull request Aug 3, 2026

Add sync feature flags for unified device list #9380

Merged

MiSikora approved these changes Aug 4, 2026

View reviewed changes

CDRussell added 2 commits August 4, 2026 09:51

Remove singleton annotation from sync unified device list helpers

b11629a

Add @workerthread annotation

3bde2d4

CDRussell merged commit 5f9a1c0 into develop Aug 4, 2026
14 checks passed

CDRussell deleted the feature/craig/sync_unified_device_list_device_info_patch branch August 4, 2026 09:04

CDRussell mentioned this pull request Aug 5, 2026

Remove gzip exclusion from /sync/devices endpoint now that backend supports it #9405

Merged

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Sync: Write & verify device_info via dev settings - #9369

Sync: Write & verify device_info via dev settings#9369
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Description

Steps to test this PR

Rename via device_info PATCH works

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