如何结合SecretKey使用cwac-saferoom？能否用Android KeyStore生成的java.security.Key实例化SafeHelperFactory？

Hey there! Let's break down your questions about CWAC-Saferoom clearly and practically:

Integrating a SecretKey with CWAC-Saferoom is straightforward once you have a valid key. Here's the step-by-step process:

• First, ensure you have a secure SecretKey (either generated locally, retrieved from Android KeyStore, or loaded from a trusted secure storage—never hardcode keys in your app).
• Use your SecretKey to create a SafeHelperFactory instance, which handles the encryption logic for Room.
• Pass this factory to Room's database builder via the openHelperFactory() method when initializing your database.

Here's a code example to illustrate:

// Assume you've already obtained your SecretKey (e.g., from Android KeyStore)
SecretKey mySecureKey = ...;

// Create the SafeHelperFactory using your SecretKey
SafeHelperFactory encryptionFactory = SafeHelperFactory.create(mySecureKey);

// Initialize your encrypted Room database
MyAppDatabase encryptedDb = Room.databaseBuilder(
        getApplicationContext(),
        MyAppDatabase.class,
        "encrypted_app_db"
    )
    .openHelperFactory(encryptionFactory)
    .build();

Yes—but only if the KeyStore-generated key is a SecretKey (symmetric encryption key like AES). CWAC-Saferoom relies on AES encryption for database protection, so asymmetric keys (like RSA PrivateKey/PublicKey) won't work here.

Here's how to generate an AES SecretKey in Android KeyStore and use it with Saferoom:

// Generate an AES SecretKey stored in Android KeyStore
KeyGenerator keyGenerator = KeyGenerator.getInstance(
    KeyProperties.KEY_ALGORITHM_AES,
    "AndroidKeyStore"
);

keyGenerator.init(new KeyGenParameterSpec.Builder(
    "saferoom_db_key", // Unique alias for your key
    KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT
)
    .setBlockModes(KeyProperties.BLOCK_MODE_GCM)
    .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
    .setUserAuthenticationRequired(false) // Adjust based on your security needs
    .build());

SecretKey keyStoreAesKey = keyGenerator.generateKey();

// Use this KeyStore-generated SecretKey to create the factory
SafeHelperFactory factory = SafeHelperFactory.create(keyStoreAesKey);

// Initialize your encrypted database as before
MyAppDatabase db = Room.databaseBuilder(
        getApplicationContext(),
        MyAppDatabase.class,
        "keystore_protected_db"
    )
    .openHelperFactory(factory)
    .build();

Just remember: If you try to use a non-secret key (like RSA) from KeyStore, Saferoom will throw an error since it doesn't support asymmetric encryption for database files. Stick to AES SecretKeys for this use case.

内容的提问来源于stack exchange，提问作者DamienL