[desktop] use electron safeStorage to store device keys

* renames PathUtils.swapFilename to replaceLastComponent
* provides a new impl for SecretStorage
* uses electron.safeStorage to encrypt the device key that then gets
stored in a file in app.getPath('userData')/safe_storage/
* from now on, per-user data is encrypted with a per-user key,
even for per-machine installs.

#3733
close #3676

src/desktop/DesktopMain.ts

@@ -21,8 +21,9 @@ import {DesktopTray} from "./tray/DesktopTray"
 import {log} from "./DesktopLog"
 import {UpdaterWrapperImpl} from "./UpdaterWrapper"
 import {ElectronNotificationFactory} from "./NotificatonFactory"
-import {KeytarSecretStorage} from "./sse/SecretStorage"
+import {SafeStorageSecretStorage} from "./sse/SecretStorage"
 import fs from "fs"
+import path from "path"
 import {DesktopIntegrator, getDesktopIntegratorForPlatform} from "./integration/DesktopIntegrator"
 import net from "net"
 import child_process from "child_process"
@@ -106,7 +107,7 @@ if (opts.registerAsMailHandler && opts.unregisterAsMailHandler) {
 
 async function createComponents(): Promise<Components> {
 	lang.init(en)
-	const secretStorage = new KeytarSecretStorage()
+	const secretStorage = new SafeStorageSecretStorage(electron, fs, path)
 	const keyStoreFacade = new KeyStoreFacadeImpl(secretStorage, desktopCrypto)
 	const configMigrator = new DesktopConfigMigrator(desktopCrypto, keyStoreFacade, electron)
 	const conf = new DesktopConfig(app, configMigrator, keyStoreFacade, desktopCrypto)

src/desktop/PathUtils.ts

@@ -122,9 +122,9 @@ export function urlIsPrefix(prefix: URL, url: URL): boolean {
 }
 
 /**
- * replace the last component in a file path with another
+ * replace the last component in a path with another
  * @param p path to a file/folder
- * @param file the file name to put in the last path component
+ * @param file the name to put in the last path component
  * @param pathModule path module to use for cross platform testing
  */
 export function swapFilename(p: string, file: string, pathModule: PathExports = path): string {