From a8432d48a4367cea76dad1deeaefaef9e03c0ace Mon Sep 17 00:00:00 2001
From: Max Schwinghammer <maxschwinghammer@outlook.com>
Date: Wed, 29 Oct 2025 14:27:50 +0100
Subject: [PATCH] Potential fix for code scanning alert no. 8: Insecure local
 authentication

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>
---
 .../viewmodel/ProfileSettingsViewModel.kt     | 41 +++++++++++++++++--
 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/com/freshkeeper/screens/profileSettings/viewmodel/ProfileSettingsViewModel.kt b/app/src/main/java/com/freshkeeper/screens/profileSettings/viewmodel/ProfileSettingsViewModel.kt
index 603bc03..e1ecdf1 100644
--- a/app/src/main/java/com/freshkeeper/screens/profileSettings/viewmodel/ProfileSettingsViewModel.kt
+++ b/app/src/main/java/com/freshkeeper/screens/profileSettings/viewmodel/ProfileSettingsViewModel.kt
@@ -17,6 +17,13 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import javax.inject.Inject
 
+import java.security.KeyStore
+import javax.crypto.Cipher
+import javax.crypto.KeyGenerator
+import javax.crypto.SecretKey
+import android.security.keystore.KeyGenParameterSpec
+import android.security.keystore.KeyProperties
+
 @HiltViewModel
 class ProfileSettingsViewModel
     @Inject
@@ -114,15 +121,38 @@ class ProfileSettingsViewModel
 
             activity?.let {
                 val executor = ContextCompat.getMainExecutor(context)
+
+                // Ensure key exists. Safe to call each time.
+                generateSecretKey()
+                val cipher = try {
+                    getCipher()
+                } catch (e: Exception) {
+                    _isBiometricEnabled.value = false
+                    return
+                }
+
                 val biometricPrompt =
                     BiometricPrompt(
                         it,
                         executor,
                         object : BiometricPrompt.AuthenticationCallback() {
                             override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
-                                launchCatching {
-                                    accountService.updateBiometricEnabled(true)
-                                    _isBiometricEnabled.value = true
+                                // Use the cipher to prove authentication!
+                                val cryptoObject = result.cryptoObject
+                                val cipher = cryptoObject?.cipher
+                                if (cipher != null) {
+                                    try {
+                                        // Encrypt some dummy data as a proof of auth; discard result
+                                        cipher.doFinal(ByteArray(16))
+                                        launchCatching {
+                                            accountService.updateBiometricEnabled(true)
+                                            _isBiometricEnabled.value = true
+                                        }
+                                    } catch (e: Exception) {
+                                        _isBiometricEnabled.value = false
+                                    }
+                                } else {
+                                    _isBiometricEnabled.value = false
                                 }
                             }
 
@@ -147,7 +177,10 @@ class ProfileSettingsViewModel
                         .setNegativeButtonText(context.getString(R.string.cancel))
                         .build()
 
-                biometricPrompt.authenticate(promptInfo)
+                biometricPrompt.authenticate(
+                    BiometricPrompt.CryptoObject(cipher),
+                    promptInfo
+                )
             } ?: run {
                 _isBiometricEnabled.value = false
             }