How to use KeyGenerator with PasswordProtection

Question

Let me start off by saying that I am a noob in the whole encryption thing. I am trying to generate a key and store it in the Android KeyStore protected with a password. I think I need PasswordProtection for this.

Storing a generated key and storing it in the keystone works with the code below. Since this code does not use the Keystore.setEntry function, which takes a KeyStore.ProtectionParameter, to store the key, I do not know how to add the PasswordProtection using KeyGenerator.

How can I store the key that is protected with a password? I got the code from the MongoDB Realm docs. Thanks in advance! :)

// generate secret key
    val keyGenerator: KeyGenerator
    keyGenerator = try {
        KeyGenerator.getInstance(
                KeyProperties.KEY_ALGORITHM_AES,
                "AndroidKeyStore")
    } catch (e: NoSuchAlgorithmException) {
        Log.e("EXAMPLE", "Failed to access the key generator.")
        throw RuntimeException(e)
    }

    val keySpec = KeyGenParameterSpec.Builder(
            "realm_key",
            KeyProperties.PURPOSE_ENCRYPT or KeyProperties.PURPOSE_DECRYPT)
            .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
            .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
            .setUserAuthenticationRequired(true)
            .setUserAuthenticationValidityDurationSeconds(
                   AUTH_VALID_DURATION_IN_SECOND)
            .build()
    try {
        keyGenerator.init(keySpec)
    } catch (e: InvalidAlgorithmParameterException) {
        Log.e("EXAMPLE", "Failed to generate a secret key.")
        throw RuntimeException(e)
    }
    keyGenerator.generateKey()