Fix local backup restore v2 in regV5.

app/src/main/java/org/thoughtcrime/securesms/registration/v2/AppRegistrationStorageController.kt

@@ -53,6 +53,7 @@ import org.thoughtcrime.securesms.database.model.databaseprotos.LinkedDeviceInfo
 import org.thoughtcrime.securesms.database.model.databaseprotos.LocalRegistrationMetadata
 import org.thoughtcrime.securesms.database.model.databaseprotos.RestoreDecisionState
 import org.thoughtcrime.securesms.dependencies.AppDependencies
+import org.thoughtcrime.securesms.jobs.LocalBackupRestoreMediaJob
 import org.thoughtcrime.securesms.keyvalue.Completed
 import org.thoughtcrime.securesms.keyvalue.NewAccount
 import org.thoughtcrime.securesms.keyvalue.PhoneNumberPrivacyValues
@@ -293,7 +294,8 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
 
     try {
       if (!FullBackupImporter.validatePassphrase(context, uri, passphrase)) {
-        emit(LocalBackupRestoreProgress.Error(IllegalArgumentException("Invalid passphrase")))
+        Log.w(TAG, "V1 restore failed: incorrect passphrase")
+        emit(LocalBackupRestoreProgress.IncorrectCredential)
         return@flow
       }
 
@@ -346,8 +348,27 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
       val messageBackupKey = aep.deriveMessageBackupKey()
       val snapshotFileSystem = SnapshotFileSystem(context, backupDir)
 
+      if (!LocalArchiver.canDecryptMainArchive(snapshotFileSystem, messageBackupKey)) {
+        Log.w(TAG, "V2 restore failed: recovery key cannot decrypt backup")
+        emit(LocalBackupRestoreProgress.IncorrectCredential)
+        return@flow
+      }
+
       when (val result = LocalArchiver.import(snapshotFileSystem, selfData, messageBackupKey)) {
         is Result.Success -> {
+          AppDependencies.jobManager.add(LocalBackupRestoreMediaJob.create(rootUri))
+
+          // Only adopt the entered recovery key as the account's AEP if the backup actually belongs to this account.
+          // Otherwise we'd overwrite the account's real AEP with a foreign backup's key. Messages are still imported.
+          val actualBackupId = LocalArchiver.getBackupId(snapshotFileSystem, messageBackupKey)
+          val expectedBackupId = SignalStore.account.accountEntropyPool.deriveMessageBackupKey().deriveBackupId(selfAci)
+          if (actualBackupId?.value?.contentEquals(expectedBackupId.value) == true) {
+            Log.i(TAG, "V2 local backup belongs to current account; adopting entered recovery key.")
+            SignalStore.account.restoreAccountEntropyPool(aep)
+            updateInProgressRegistrationData { this.accountEntropyPool = aep.value }
+          } else {
+            Log.w(TAG, "V2 local backup does not belong to current account; keeping existing recovery key.")
+          }
           emit(LocalBackupRestoreProgress.Complete)
           Log.d(TAG, "V2 restore complete.")
         }

feature/registration/src/main/java/org/signal/registration/screens/localbackuprestore/LocalBackupRestoreScreen.kt

@@ -100,6 +100,9 @@ fun LocalBackupRestoreScreen(
     LocalBackupRestoreState.RestorePhase.InProgress -> {
       InProgressContent(progressFraction = state.progressFraction, onEvent = onEvent, modifier = modifier)
     }
+    LocalBackupRestoreState.RestorePhase.IncorrectCredential -> {
+      IncorrectCredentialContent(backupType = state.backupInfo?.type, onEvent = onEvent, modifier = modifier)
+    }
     LocalBackupRestoreState.RestorePhase.Error -> {
       ErrorContent(errorMessage = state.errorMessage, onEvent = onEvent, modifier = modifier)
     }
@@ -530,6 +533,41 @@ private fun InProgressContent(
   )
 }
 
+@Composable
+private fun IncorrectCredentialContent(
+  backupType: LocalBackupInfo.BackupType?,
+  onEvent: (LocalBackupRestoreEvents) -> Unit,
+  modifier: Modifier = Modifier
+) {
+  val headline = if (backupType == LocalBackupInfo.BackupType.V1) {
+    stringResource(R.string.LocalBackupRestoreScreen__incorrect_passphrase)
+  } else {
+    stringResource(R.string.LocalBackupRestoreScreen__incorrect_recovery_key)
+  }
+
+  LocalBackupRestoreLayout(
+    modifier = modifier,
+    description = {
+      Description(
+        headline = headline,
+        body = stringResource(R.string.LocalBackupRestoreScreen__incorrect_credential_description)
+      )
+    },
+    content = {},
+    primaryButton = { buttonModifier ->
+      OutlinedButton(
+        onClick = { onEvent(LocalBackupRestoreEvents.RestoreBackup) },
+        modifier = buttonModifier
+      ) {
+        Text(text = stringResource(R.string.LocalBackupRestoreScreen__try_again))
+      }
+    },
+    secondaryButton = { buttonModifier ->
+      CancelButton(onEvent, buttonModifier)
+    }
+  )
+}
+
 @Composable
 private fun ErrorContent(
   errorMessage: String?,
@@ -671,3 +709,23 @@ private fun LocalBackupRestoreScreenErrorPreview() {
     )
   }
 }
+
+@AllDevicePreviews
+@Composable
+private fun LocalBackupRestoreScreenIncorrectCredentialPreview() {
+  Previews.Preview {
+    LocalBackupRestoreScreen(
+      state = LocalBackupRestoreState(
+        restorePhase = LocalBackupRestoreState.RestorePhase.IncorrectCredential,
+        backupInfo = LocalBackupInfo(
+          type = LocalBackupInfo.BackupType.V2,
+          date = LocalDateTime.of(2026, 3, 15, 14, 30, 0),
+          name = "signal-backup-2026-03-15-14-30-00",
+          uri = Uri.EMPTY,
+          sizeBytes = 511.mebiBytes.bytes
+        )
+      ),
+      onEvent = {}
+    )
+  }
+}

feature/registration/src/main/java/org/signal/registration/screens/localbackuprestore/LocalBackupRestoreState.kt

@@ -42,6 +42,9 @@ data class LocalBackupRestoreState(
     /** Restore is actively in progress. */
     InProgress,
 
+    /** The entered passphrase/recovery key could not decrypt the backup. */
+    IncorrectCredential,
+
     /** Restore failed. */
     Error
   }

feature/registration/src/main/java/org/signal/registration/screens/localbackuprestore/LocalBackupRestoreViewModel.kt

@@ -111,10 +111,6 @@ class LocalBackupRestoreViewModel(
   }
 
   private suspend fun onRestoreComplete(state: LocalBackupRestoreState) {
-    if (state.aep != null) {
-      parentEventEmitter(RegistrationFlowEvent.UserSuppliedAepVerified(state.aep))
-    }
-
     if (isPreRegistration) {
       resultBus.sendResult(resultKey, LocalBackupRestoreResult.Success(state.aep))
       parentEventEmitter.navigateBack()
@@ -187,6 +183,10 @@ class LocalBackupRestoreViewModel(
             onRestoreComplete(_localState.value.copy(aep = currentState.aep, v1Passphrase = currentState.v1Passphrase))
             _localState.value
           }
+          is LocalBackupRestoreProgress.IncorrectCredential -> {
+            Log.w(TAG, "Restore failed: incorrect passphrase/recovery key")
+            currentState.copy(restorePhase = LocalBackupRestoreState.RestorePhase.IncorrectCredential)
+          }
           is LocalBackupRestoreProgress.Error -> {
             Log.w(TAG, "Restore failed", progress.cause)
             LocalBackupRestoreState(

feature/registration/src/main/res/values/strings.xml

@@ -236,6 +236,12 @@
     <string name="LocalBackupRestoreScreen__restore_failed_description">An error occurred while restoring your backup. Please try again.</string>
     <!-- Button to retry restore after failure -->
     <string name="LocalBackupRestoreScreen__try_again">Try again</string>
+    <!-- Title shown when the entered passphrase cannot decrypt the selected backup -->
+    <string name="LocalBackupRestoreScreen__incorrect_passphrase">Incorrect passphrase</string>
+    <!-- Title shown when the entered recovery key cannot decrypt the selected backup -->
+    <string name="LocalBackupRestoreScreen__incorrect_recovery_key">Incorrect recovery key</string>
+    <!-- Description shown when the entered passphrase or recovery key cannot decrypt the selected backup -->
+    <string name="LocalBackupRestoreScreen__incorrect_credential_description">The credential you entered doesn\'t match this backup. Please check it and try again.</string>
     <!-- Button to link an existing Signal account to this device -->
     <string name="WelcomeScreen__link_your_account">Link your account</string>
     <!-- Prompt shown to users who don\'t have a Signal account yet -->

feature/registration/src/test/java/org/signal/registration/screens/localbackuprestore/LocalBackupRestoreViewModelTest.kt

@@ -22,6 +22,7 @@ import io.mockk.mockk
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.launch
 import kotlinx.coroutines.test.UnconfinedTestDispatcher
 import kotlinx.coroutines.test.resetMain
 import kotlinx.coroutines.test.runTest
@@ -270,4 +271,54 @@ class LocalBackupRestoreViewModelTest {
     coVerify { mockRepository.restoreAccountRecord(any()) }
     assertThat(emittedParentEvents).contains(RegistrationFlowEvent.RegistrationComplete)
   }
+
+  // ==================== Incorrect Credential Tests ====================
+
+  @Test
+  fun `V1 restore with incorrect passphrase surfaces IncorrectCredential and does not complete`() = runTest(testDispatcher) {
+    val viewModel = createViewModel(isPreRegistration = false)
+    backgroundScope.launch { viewModel.state.collect {} }
+
+    val backupInfo = LocalBackupInfo(
+      type = LocalBackupInfo.BackupType.V1,
+      date = LocalDateTime.now(),
+      name = "backup.backup",
+      uri = mockk()
+    )
+    val initialState = LocalBackupRestoreState(backupInfo = backupInfo)
+
+    every { mockRepository.restoreV1Backup(any(), any()) } returns flowOf(LocalBackupRestoreProgress.IncorrectCredential)
+
+    viewModel.applyEvent(initialState, LocalBackupRestoreEvents.PassphraseSubmitted("passphrase"), stateEmitter)
+
+    assertThat(viewModel.state.value.restorePhase).isEqualTo(LocalBackupRestoreState.RestorePhase.IncorrectCredential)
+    assertThat(emittedParentEvents).isEmpty()
+    coVerify(exactly = 0) { mockRepository.setRestoreDecision(any()) }
+  }
+
+  @Test
+  fun `V2 restore with incorrect recovery key surfaces IncorrectCredential and does not complete`() = runTest(testDispatcher) {
+    val viewModel = createViewModel(isPreRegistration = false)
+    backgroundScope.launch { viewModel.state.collect {} }
+
+    val backupInfo = LocalBackupInfo(
+      type = LocalBackupInfo.BackupType.V2,
+      date = LocalDateTime.now(),
+      name = "signal-backup",
+      uri = mockk()
+    )
+    val initialState = LocalBackupRestoreState(backupInfo = backupInfo, selectedFolderUri = mockk())
+
+    every { mockRepository.restoreV2Backup(any(), any(), any()) } returns flowOf(LocalBackupRestoreProgress.IncorrectCredential)
+
+    viewModel.applyEvent(initialState, LocalBackupRestoreEvents.PassphraseSubmitted(VALID_AEP), stateEmitter)
+
+    assertThat(viewModel.state.value.restorePhase).isEqualTo(LocalBackupRestoreState.RestorePhase.IncorrectCredential)
+    assertThat(emittedParentEvents).isEmpty()
+    coVerify(exactly = 0) { mockRepository.setRestoreDecision(any()) }
+  }
+
+  companion object {
+    private const val VALID_AEP = "uy38jh2778hjjhj8lk19ga61s672jsj089r023s6a57809bap92j2yh5t326vv7t"
+  }
 }

lib/archive/src/main/java/org/signal/archive/LocalBackupRestoreProgress.kt

@@ -25,6 +25,9 @@ sealed interface LocalBackupRestoreProgress {
   /** The restore completed successfully. */
   data object Complete : LocalBackupRestoreProgress
 
+  /** The provided passphrase (V1) or recovery key (V2) could not decrypt the backup. */
+  data object IncorrectCredential : LocalBackupRestoreProgress
+
   /** The restore failed with an error. */
   data class Error(val cause: Throwable) : LocalBackupRestoreProgress
 }