How do I initialize a TrustManagerFactory with multiple sources of trust?

Question

My application has a personal keystore containing trusted self-signed certificates for use in the local network - say mykeystore.jks. I wish to be able to conne

Answer 1

I've run into the same issue with Commons HttpClient. Working solution for my case was to create delegation chain for PKIX TrustManagers in following way:

public class TrustManagerDelegate implements X509TrustManager {
    private final X509TrustManager mainTrustManager;
    private final X509TrustManager trustManager;
    private final TrustStrategy trustStrategy;

    public TrustManagerDelegate(X509TrustManager mainTrustManager, X509TrustManager trustManager, TrustStrategy trustStrategy) {
        this.mainTrustManager = mainTrustManager;
        this.trustManager = trustManager;
        this.trustStrategy = trustStrategy;
    }

    @Override
    public void checkClientTrusted(
            final X509Certificate[] chain, final String authType) throws CertificateException {
        this.trustManager.checkClientTrusted(chain, authType);
    }

    @Override
    public void checkServerTrusted(
            final X509Certificate[] chain, final String authType) throws CertificateException {
        if (!this.trustStrategy.isTrusted(chain, authType)) {
            try {
                mainTrustManager.checkServerTrusted(chain, authType);
            } catch (CertificateException ex) {
                this.trustManager.checkServerTrusted(chain, authType);
            }
        }
    }

    @Override
    public X509Certificate[] getAcceptedIssuers() {
        return this.trustManager.getAcceptedIssuers();
    }

}

And initialize HttpClient in following way (yes it's ugly):

final SSLContext sslContext;
try {
    sslContext = SSLContext.getInstance("TLS");
    final TrustManagerFactory javaDefaultTrustManager = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
    javaDefaultTrustManager.init((KeyStore)null);
    final TrustManagerFactory customCaTrustManager = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
    customCaTrustManager.init(getKeyStore());

    sslContext.init(
        null,
        new TrustManager[]{
            new TrustManagerDelegate(
                    (X509TrustManager)customCaTrustManager.getTrustManagers()[0],
                    (X509TrustManager)javaDefaultTrustManager.getTrustManagers()[0],
                    new TrustSelfSignedStrategy()
            )
        },
        secureRandom
    );

} catch (final NoSuchAlgorithmException ex) {
    throw new SSLInitializationException(ex.getMessage(), ex);
} catch (final KeyManagementException ex) {
    throw new SSLInitializationException(ex.getMessage(), ex);
}

SSLConnectionSocketFactory sslSocketFactory = new SSLConnectionSocketFactory(sslContext);

PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(
        RegistryBuilder.create()
                .register("http", PlainConnectionSocketFactory.getSocketFactory())
                .register("https", sslSocketFactory)
                .build()
);
//maximum parallel requests is 500
cm.setMaxTotal(500);
cm.setDefaultMaxPerRoute(500);

CredentialsProvider cp = new BasicCredentialsProvider();
cp.setCredentials(
        new AuthScope(apiSettings.getIdcApiUrl(), 443),
        new UsernamePasswordCredentials(apiSettings.getAgencyId(), apiSettings.getAgencyPassword())
);

client = HttpClients.custom()
                    .setConnectionManager(cm)
                    .build();

In your case with simple HttpsURLConnection you may get by with simplified version of delegating class:

public class TrustManagerDelegate implements X509TrustManager {
    private final X509TrustManager mainTrustManager;
    private final X509TrustManager trustManager;

    public TrustManagerDelegate(X509TrustManager mainTrustManager, X509TrustManager trustManager) {
        this.mainTrustManager = mainTrustManager;
        this.trustManager = trustManager;
    }

    @Override
    public void checkClientTrusted(
            final X509Certificate[] chain, final String authType) throws CertificateException {
        this.trustManager.checkClientTrusted(chain, authType);
    }

    @Override
    public void checkServerTrusted(
            final X509Certificate[] chain, final String authType) throws CertificateException {
        try {
            mainTrustManager.checkServerTrusted(chain, authType);
        } catch (CertificateException ex) {
            this.trustManager.checkServerTrusted(chain, authType);
        }
    }

    @Override
    public X509Certificate[] getAcceptedIssuers() {
        return this.trustManager.getAcceptedIssuers();
    }

}