Save and retrieve keypair in Android keystore

I need to generate an RSA 2018 key pair, then save and restore it (if any)

At this moment, I have:

SecureRandom random = new SecureRandom();
RSAKeyGenParameterSpec spec = new RSAKeyGenParameterSpec(keySize, RSAKeyGenParameterSpec.F4);
KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "SC");
generator.initialize(spec, random);
return generator.generateKeyPair();

The effect is very good, but now I try to save and get it from Android keystore, but I don't realize it. I've tried:

String alias = "TESTINGKEY";
        KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
        keyStore.load(null);
        if (!keyStore.containsAlias(alias)) {
            SecureRandom random = new SecureRandom();
            RSAKeyGenParameterSpec spec = new RSAKeyGenParameterSpec(keySize, RSAKeyGenParameterSpec.F4);
            KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "SC");
            generator.initialize(spec, random);
            return generator.generateKeyPair();
        } else {
            Key key = keyStore.getKey(alias, null);
            if (key instanceof PrivateKey) {
                Certificate cert = keyStore.getCertificate(alias);
                return new KeyPair(cert.getPublicKey(), (PrivateKey) key);
            } else {
                return null;
            }
        }

However, it does not work properly because the keystore does not contain key pairs in the second run of the application

stay https://developer.android.com/training/articles/keystore.html?hl=es In, I saw keygenparameterspec, which has an alias value, but int rsakeygenparameterspec does not

How do I save it?

resolvent:

Using androidkeystore requires keygenparameterspec.builder to generate keys. Also use androidkeystore instead of SC. you can use the following code

Generate key (Android > = 23)

KeyPairGenerator kpg = KeyPairGenerator.getInstance(
                KeyProperties.KEY_ALGORITHM_RSA, "AndroidKeyStore");

kpg.initialize(new KeyGenParameterSpec.Builder(
                alias,
                KeyProperties.PURPOSE_SIGN | KeyProperties.PURPOSE_VERIFY)
                .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512)
                .setKeySize(keySize)
                .build());

KeyPair keyPair = kpg.generateKeyPair();

Load key

KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);
KeyStore.Entry entry = keyStore.getEntry(alias, null);
PrivateKey privateKey = ((KeyStore.PrivateKeyEntry) entry).getPrivateKey();
PublicKey publicKey = keyStore.getCertificate(alias).getPublicKey();