获取Java SSLSocket的受信任的X509证书

Question

I'm able to establish a TLS connection to https://google.com/ . The remote service returns a chain of 3 certificates:

• CN=www.google.com, O=Google Inc, L=Mountain View, ST=California, C=US
• CN=Google Internet Authority G2, O=Google Inc, C=US
• CN=GeoTrust Global CA, O=GeoTrust Inc., C=US

These certificates can be retrieved like so:

Certificate[] certificates = sslSocket.getSession().getPeerCertificates();

Unfortunately, this isn't the complete chain. There's a 4th certificate that's installed in my local SSL context's TrustManager. It looks like this:

• OU=Equifax Secure Certificate Authority, O=Equifax, C=US

Retrieving its name is straightforward:

String equifax = ((X509Certificate) peerCertificates[2]).getIssuerDN().getName();

What I want instead is the X509Certificate instance. How do I get the trusted CA cert that was used during a SSLSocket handshake?

Note that I'm using the system's TrustManager by creating the SSL context like this:

SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(null, null, null);

Answer 1

You are almost there, just use the JVM default trust manager:

public static void main(String[] args) throws Exception{

    SSLSocketFactory factory = (SSLSocketFactory) SSLSocketFactory.getDefault();
    SSLSocket socket = (SSLSocket)factory.createSocket("www.google.com", 443);

    X509Certificate[] chain = socket.getSession().getPeerCertificateChain();

    String equifax = chain[2].getIssuerDN().getName();

    // JVM Default Trust Managers
    TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
    trustManagerFactory.init((KeyStore) null);
    TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();

    X509TrustManager manager = (X509TrustManager) trustManagers[0];

    for (java.security.cert.X509Certificate x509Certificate : manager.getAcceptedIssuers()) {
        if (equifax.equals(x509Certificate.getSubjectDN().getName())) {
            System.out.println(x509Certificate);
        }
    }

}

Answer 2

For perpetuity, I ended up getting the data I wanted with dirty reflection . I'm unable to control how the caller builds the SSL Context, as advised above.