From 5947fc84919d82e12044704cfd7622b01a0e5f94 Mon Sep 17 00:00:00 2001
From: Matej Kriz <matej@matejkriz.cz>
Date: Tue, 4 Feb 2025 16:35:47 +0100
Subject: [PATCH] fix(suite-native): prevent occasional data losses

From Sentry reports it seems that on iOS it happens mostly on the background without user interaction (hypothesis is that after automatic app update iOS starts the app).

On Android, it might happen during app start from time to time, not sure why and when.

When the reading from the secure store fails, we used to immediately reset the key and make all user data inaccessible. Now we will always ask the user to either try to restart the app or reset the storage if it doesn't help.
---
 suite-native/storage/src/storage.ts | 81 +++++++++++++++++++----------
 1 file changed, 53 insertions(+), 28 deletions(-)

diff --git a/suite-native/storage/src/storage.ts b/suite-native/storage/src/storage.ts
index 3f19a8a0085..8240ecffe3b 100644
--- a/suite-native/storage/src/storage.ts
+++ b/suite-native/storage/src/storage.ts
@@ -16,18 +16,32 @@ export const ENCRYPTED_STORAGE_ID = 'trezorSuite-app-storage';
 export let encryptedStorage: MMKV;
 
 const retrieveStorageEncryptionKey = async () => {
+    let secureKey: string | null = null;
     try {
-        const secureKey = await SecureStore.getItemAsync(ENCRYPTION_KEY);
-
-        if (secureKey) return secureKey;
+        secureKey = await SecureStore.getItemAsync(ENCRYPTION_KEY);
     } catch (error) {
-        // Some users are facing an error when they uninstall the app and then reinstall it,
-        // see https://github.com/expo/expo/issues/23426
-        await SecureStore.deleteItemAsync(ENCRYPTION_KEY);
-        captureException(error);
+        // If there is an error, report it and try to read one more time.
+        captureException(error, { tags: { attempt: 1 } });
+        try {
+            // There were some trouble reading from the SecureStore,
+            // let's wait a bit to make sure it wasn't just temporary error.
+            await new Promise(resolve => setTimeout(resolve, 100));
+            secureKey = await SecureStore.getItemAsync(ENCRYPTION_KEY);
+        } catch (error) {
+            captureException(error, { tags: { attempt: 2 } });
+
+            // It's not possible to read from SecureStore,
+            // and we don't want to set a new key or reset storage without user interaction.
+            // It might happen on the background when the phone is locked.
+            return null;
+        }
     }
 
-    const secureKey = Buffer.from(getRandomBytes(16)).toString('hex');
+    if (secureKey) return secureKey;
+
+    // If we are here, it means that we have no encryption key in storage.
+    // We need to generate a new one. This should happen only once on first app start.
+    secureKey = Buffer.from(getRandomBytes(16)).toString('hex');
     await SecureStore.setItemAsync(ENCRYPTION_KEY, secureKey);
 
     return secureKey;
@@ -39,9 +53,30 @@ export const clearStorage = () => {
     RNRestart.restart();
 };
 
-// Ideally it should never happen but we need to be sure that at least some message is displayed.
-// If someone will mess with encryptionKey it can corrupt storage and app will crash on startup.
-// Then app will hang on splashscreen indefinitely so we at least want to show some error message.
+const alertUser = () => {
+    // If storage can't load, app is never set as ready so we need to hide splash screen here to make the alert visible.
+    SplashScreen.hideAsync();
+    Alert.alert(
+        'Unable to load app data',
+        'Try restarting the app. If the issue persists, you may need to clear the app’s storage. This won’t affect assets on your Trezor device.',
+        [
+            {
+                text: 'Clear app storage',
+                onPress: clearStorage,
+                style: 'destructive',
+            },
+            {
+                text: 'Restart app',
+                onPress: () => {
+                    RNRestart.restart();
+                },
+                isPreferred: true,
+                style: 'default',
+            },
+        ],
+    );
+};
+
 const tryInitStorage = (encryptionKey: string) => {
     try {
         return new MMKV({
@@ -49,23 +84,7 @@ const tryInitStorage = (encryptionKey: string) => {
             encryptionKey,
         });
     } catch (error) {
-        SplashScreen.hideAsync();
-        Alert.alert(
-            'Encrypted storage error',
-            `Storage is corrupted. Please reinstall the app or reset storage. \n Error: ${error.toString()}`,
-            [
-                {
-                    text: 'OK',
-                    onPress: () => {
-                        // do nothing
-                    },
-                },
-                {
-                    text: 'Reset storage',
-                    onPress: clearStorage,
-                },
-            ],
-        );
+        alertUser();
         // rethrow error so it can be caught by Sentry
         throw error;
     }
@@ -75,6 +94,12 @@ export const initMmkvStorage = async (): Promise<Storage> => {
     // storage may be already initialized (for example in dev useEffect fire twice)
     if (!encryptedStorage) {
         const encryptionKey = await retrieveStorageEncryptionKey();
+
+        if (!encryptionKey) {
+            alertUser();
+            throw new Error('Encryption key is unreadable!');
+        }
+
         encryptedStorage = tryInitStorage(encryptionKey);
     }