Android KeyGenerator for API < 23

Question

I want to try using Android Keystore system to encrypt and decrypt data, i tried a sample that works fine for API >= 23, but it's not working for API below 23.

here is a sample code :

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
    keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, ANDROID_KEY_STORE);

    keyGenerator.init(new KeyGenParameterSpec.Builder(alias, KeyProperties.PURPOSE_ENCRYPT | 
        KeyProperties.PURPOSE_DECRYPT)
            .setBlockModes(KeyProperties.BLOCK_MODE_GCM)
            .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
            .build());
} else {
    keyGenerator = KeyGenerator.getInstance(ANDROID_KEY_STORE);
    // how to implement here

    keyGenerator.init(...);
}

i need to deal with API < 23, thank you.