How can I get a list of trusted root certificates in Java?

Question

I would like to be able to get access to all trusted root certificates programmatically in a Java app.

I was looking at the keystore interface, but I'm hoping to get the list of trusted roots that's implicit with the JRE.

Is this accessible anywhere?

Answer 1

There's an example that shows how to get a Set of the root certificates and iterate through them called Listing the Most-Trusted Certificate Authorities (CA) in a Key Store . Here's a slightly modified version that prints out each certificate (tested on Windows Vista).

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.PKIXParameters;
import java.security.cert.TrustAnchor;
import java.security.cert.X509Certificate;
import java.util.Iterator;


public class Main {

    public static void main(String[] args) {
        try {
            // Load the JDK's cacerts keystore file
            String filename = System.getProperty("java.home") + "/lib/security/cacerts".replace('/', File.separatorChar);
            FileInputStream is = new FileInputStream(filename);
            KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
            String password = "changeit";
            keystore.load(is, password.toCharArray());

            // This class retrieves the most-trusted CAs from the keystore
            PKIXParameters params = new PKIXParameters(keystore);

            // Get the set of trust anchors, which contain the most-trusted CA certificates
            Iterator it = params.getTrustAnchors().iterator();
            while( it.hasNext() ) {
                TrustAnchor ta = (TrustAnchor)it.next();
                // Get certificate
                X509Certificate cert = ta.getTrustedCert();
                System.out.println(cert);
            }
        } catch (CertificateException e) {
        } catch (KeyStoreException e) {
        } catch (NoSuchAlgorithmException e) {
        } catch (InvalidAlgorithmParameterException e) {
        } catch (IOException e) {
        } 
    }
}

Answer 2

This should be more flexible using the default trust store in the system to get all certificates:

TrustManagerFactory trustManagerFactory =
   TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
List<Certificate> x509Certificates = new ArrayList<>();
trustManagerFactory.init((KeyStore)null);                 
Arrays.asList(trustManagerFactory.getTrustManagers()).stream().forEach(t -> {
                    x509Certificates.addAll(Arrays.asList(((X509TrustManager)t).getAcceptedIssuers()));
                });

```

Answer 3

A working example, combining concept from Bill the Lizard and k_o_ answer:

import java.io.FileInputStream;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.KeyStore;
import java.security.cert.X509Certificate;

import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

public class JDKTrustStoreCertListing {

    public static void main(String[] args) throws Exception{
        
        String javaHome=System.getProperty("java.home");
        Path jdkCACertPath=Paths.get(javaHome, "lib", "security", "cacerts");
        
        TrustManagerFactory trustManagerFactory=TrustManagerFactory
                                                    .getInstance(TrustManagerFactory
                                                                    .getDefaultAlgorithm());
        
        FileInputStream fis=new FileInputStream(jdkCACertPath.toFile());
        String keystorePassword="changeit";
        
        KeyStore keyStore=KeyStore.getInstance(KeyStore.getDefaultType());
        keyStore.load(fis, keystorePassword.toCharArray());

        fis.close();
        
        trustManagerFactory.init(keyStore);
        
        TrustManager[] truestManagers=trustManagerFactory.getTrustManagers();
        for(TrustManager t:truestManagers)
            for(X509Certificate c:((X509TrustManager)t).getAcceptedIssuers())
                    System.out.println(c.getIssuerX500Principal());
    
    }//main closing

}//class closing