Fixes and comments

src/components/views/settings/devices/types.ts

@@ -18,7 +18,13 @@ import { IMyDevice } from "matrix-js-sdk/src/matrix";
 
 import { ExtendedDeviceInformation } from "../../../../utils/device/parseUserAgent";
 
-export type DeviceWithVerification = IMyDevice & { isVerified: boolean | null };
+export type DeviceWithVerification = IMyDevice & {
+    /**
+     * `null` if the device is unknown or has not published encryption keys; otherwise a boolean
+     * indicating whether the device has been cross-signed by a cross-signing key we trust.
+     */
+    isVerified: boolean | null;
+};
 export type ExtendedDeviceAppInfo = {
     // eg Element Web
     appName?: string;

src/utils/device/isDeviceVerified.ts

@@ -22,13 +22,17 @@ import { MatrixClient } from "matrix-js-sdk/src/matrix";
  * @param client - reference to the MatrixClient
  * @param deviceId - ID of the device to be checked
  *
- * @returns `true` if the device has been correctly cross-signed. `false` if the device is unknown or not correctly
- *    cross-signed. `null` if there was an error fetching the device info.
+ * @returns `null` if the device is unknown or has not published encryption keys; otherwise a boolean
+ *    indicating whether the device has been cross-signed by a cross-signing key we trust.
  */
 export const isDeviceVerified = async (client: MatrixClient, deviceId: string): Promise<boolean | null> => {
     try {
         const trustLevel = await client.getCrypto()?.getDeviceVerificationStatus(client.getSafeUserId(), deviceId);
-        return trustLevel?.crossSigningVerified ?? false;
+        if (!trustLevel) {
+            // either no crypto, or an unknown/no-e2e device
+            return null;
+        }
+        return trustLevel.crossSigningVerified;
     } catch (e) {
         console.error("Error getting device cross-signing info", e);
         return null;