How to use keystore in Java to store private key?

Question

I have used KeyPairGenerator to generate a RSA key pair. If I\'m not wrong, the KeyStore is only used to store certificates and not keys. How can I properly sto

Answer 1

This block of code will generate and store a KeyPair on the AndroidKeyStore. (NOTE: Exception catches omitted)

KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);

String alias = "my_key"; // replace as required or get it as a function argument

int nBefore = keyStore.size(); // debugging variable to help convince yourself this works

// Create the keys if necessary
if (!keyStore.containsAlias(alias)) {

    Calendar notBefore = Calendar.getInstance();
    Calendar notAfter = Calendar.getInstance();
    notAfter.add(Calendar.YEAR, 1);
    KeyPairGeneratorSpec spec = new KeyPairGeneratorSpec.Builder(this)
                    .setAlias(alias)
                    .setKeyType("RSA")
                    .setKeySize(2048)
                    .setSubject(new X500Principal("CN=test"))
                    .setSerialNumber(BigInteger.ONE)
                    .setStartDate(notBefore.getTime())
                    .setEndDate(notAfter.getTime())
                    .build();
    KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "AndroidKeyStore");
    generator.initialize(spec);

    KeyPair keyPair = generator.generateKeyPair();
}
int nAfter = keyStore.size();
Log.v(TAG, "Before = " + nBefore + " After = " + nAfter);

// Retrieve the keys
KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry)keyStore.getEntry(alias, null);
RSAPrivateKey privateKey = (RSAPrivateKey) privateKeyEntry.getPrivateKey();
RSAPublicKey publicKey = (RSAPublicKey) privateKeyEntry.getCertificate().getPublicKey();

Log.v(TAG, "private key = " + privateKey.toString());
Log.v(TAG, "public key = " + publicKey.toString());