Generate SecretKey from AndroidKeyStore

Question

According to this sample, I am trying to get SecretKey from AndroidKeyStore:

KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);
SecretKey secretKey = (SecretKey) keyStore.getKey(KEY_NAME, null);

But I get this exception:

android.security.keystore.AndroidKeyStoreRSAPrivateKey cannot be cast to javax.crypto.SecretKey

This is how I have created the key:

KeyPairGeneratorSpec spec = new KeyPairGeneratorSpec.Builder(context)
                    .setAlias(KEY_NAME)
                    .setSubject(new X500Principal("CN=" + KEY_NAME))
                    .setSerialNumber(BigInteger.valueOf(1337))
                    .setStartDate(START_TIME)
                    .setEndDate(END_TIME)
                    .build();
KeyPairGenerator kpGenerator = KeyPairGenerator.getInstance("RSA", "AndroidKeyStore");   
kpGenerator.initialize(spec);
kpGenerator.generateKeyPair();

So is there any way to generate SecretKey from AndroidKeyStore?

Answer 1

Since Android 6.0 you can generate AES keys using AndroidKeystore:

KeyGenerator kg = KeyGenerator.getInstance("AES", "AndroidKeyStore");
kg.init(keySpec);
SecretKey key = kg.generateKey();

For more details see blog post Keystore redesign in Android M (by Nikolay Elenkov).