using Certificate in https

Question

I write android application. How can I use Certificate in https connection when I initialize certificate from directory file and not from packages?

When I have packages file with password, this code works:

    KeyStore keyStore = KeyStore.getInstance("PKCS12");
    keyStore.load(certificateIs, pass.toCharArray());
    KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
    kmf.init(keyStore, pass.toCharArray());
    SSLContext sc = SSLContext.getInstance("TLS");
    sc.init(kmf.getKeyManagers(), trustAllCerts, new java.security.SecureRandom());
    HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());

But I have certificate initialized from der file:

    CertificateFactory cf = CertificateFactory.getInstance("X.509");
    X509Certificate certificate = (X509Certificate) cf.generateCertificate(certBytes);

I do not know how use this certificate over https connection.

Answer 1

You seem to be talking about client-certificate authentication (where your Android device is the client).

Firstly, you need the client to have the private key matching the public key in the certificate you're trying to use (that's the whole point, otherwise, it wouldn't authenticated anything). PKCS#12 is one of the usual formats for containing the private key and the certificate. If you only have the certificate in a der file, you probably won't have the private key in it, hence it won't work. It's not quite clear from your question what you do with your certificate variable, with respect to the KeyManagerFactory (if you have a custom X509KeyManager, it should return the private key in its getPrivateKey method, otherwise it won't work).

Secondly, client-certificate authentication is always initiated by the server, so you'd need the server to be set up accordingly too (it seems to be the case already, if your test based on a PKCS#12 keystore works).