Ask for system authentication before storing a new recovery code
This will help to prevent data extraction via seedvault when somebody gets hold of an unlocked phone. However, it will not help against someone able to force you to provide fingerprints or other device secrets.
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index c8a8da5..d3fa718 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -47,6 +47,9 @@
android:name="android.permission.QUERY_ALL_PACKAGES"
tools:ignore="QueryAllPackagesPermission" />
+ <!-- Used to authenticate saving a new recovery code -->
+ <uses-permission android:name="android.permission.USE_BIOMETRIC" />
+
<application
android:name=".App"
android:allowBackup="false"
diff --git a/app/src/main/java/com/stevesoltys/seedvault/ui/recoverycode/RecoveryCodeInputFragment.kt b/app/src/main/java/com/stevesoltys/seedvault/ui/recoverycode/RecoveryCodeInputFragment.kt
index 8211a01..8cb7fd8 100644
--- a/app/src/main/java/com/stevesoltys/seedvault/ui/recoverycode/RecoveryCodeInputFragment.kt
+++ b/app/src/main/java/com/stevesoltys/seedvault/ui/recoverycode/RecoveryCodeInputFragment.kt
@@ -1,8 +1,14 @@
package com.stevesoltys.seedvault.ui.recoverycode
import android.app.Activity.RESULT_OK
+import android.app.KeyguardManager
import android.content.Intent
+import android.hardware.biometrics.BiometricManager.Authenticators.BIOMETRIC_STRONG
+import android.hardware.biometrics.BiometricManager.Authenticators.DEVICE_CREDENTIAL
+import android.hardware.biometrics.BiometricPrompt
+import android.os.Build.VERSION.SDK_INT
import android.os.Bundle
+import android.os.CancellationSignal
import android.view.LayoutInflater
import android.view.View
import android.view.View.GONE
@@ -16,8 +22,10 @@
import android.widget.Toast
import android.widget.Toast.LENGTH_LONG
import androidx.activity.result.contract.ActivityResultContracts.StartActivityForResult
+import androidx.annotation.RequiresApi
import androidx.appcompat.app.AlertDialog
import androidx.constraintlayout.widget.ConstraintLayout
+import androidx.core.content.ContextCompat.getMainExecutor
import androidx.fragment.app.Fragment
import cash.z.ecc.android.bip39.Mnemonics
import cash.z.ecc.android.bip39.Mnemonics.ChecksumException
@@ -143,12 +151,36 @@
return
}
if (forStoringNewCode) {
- viewModel.storeNewCode(input)
+ val keyguardManager = requireContext().getSystemService(KeyguardManager::class.java)
+ if (SDK_INT >= 30 && keyguardManager.isDeviceSecure) {
+ // if we have a lock-screen secret, we can ask for it before storing the code
+ storeNewCodeAfterAuth(input)
+ } else {
+ // user doesn't seem to care about security, store key without auth
+ viewModel.storeNewCode(input)
+ }
} else {
viewModel.verifyExistingCode(input)
}
}
+ @RequiresApi(30)
+ private fun storeNewCodeAfterAuth(input: List<CharSequence>) {
+ val biometricPrompt = BiometricPrompt.Builder(context)
+ .setConfirmationRequired(true)
+ .setTitle(getString(R.string.recovery_code_auth_title))
+ .setDescription(getString(R.string.recovery_code_auth_description))
+ // BIOMETRIC_STRONG could be made optional in the future, setting guarded by credentials
+ .setAllowedAuthenticators(DEVICE_CREDENTIAL or BIOMETRIC_STRONG)
+ .build()
+ val callback = object : BiometricPrompt.AuthenticationCallback() {
+ override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult?) {
+ viewModel.storeNewCode(input)
+ }
+ }
+ biometricPrompt.authenticate(CancellationSignal(), getMainExecutor(context), callback)
+ }
+
private fun allFilledOut(input: List<CharSequence>): Boolean {
for (i in input.indices) {
if (input[i].isNotEmpty()) continue
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 7682402..046ee7a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -94,6 +94,8 @@
<string name="recovery_code_verification_new_dialog_title">Wait one second…</string>
<string name="recovery_code_verification_new_dialog_message">Generating a new code will make your existing backups inaccessible. We\'ll try to delete them if possible.\n\nAre you sure you want to do this?</string>
<string name="recovery_code_recreated">New recovery code has been created successfully</string>
+ <string name="recovery_code_auth_title">Confirm it\'s really you</string>
+ <string name="recovery_code_auth_description">This ensures that nobody else can get your data when finding your phone unlocked.</string>
<!-- Notification -->
<string name="notification_channel_title">Backup notification</string>