http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.jce;

import java.io.IOException;
import java.security.cert.CRLException;
import java.security.cert.CertificateEncodingException;
import java.security.cert.X509CRL;
import java.security.cert.X509Certificate;

import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.x509.TBSCertList;
import org.bouncycastle.asn1.x509.TBSCertificateStructure;
import org.bouncycastle.asn1.x509.X509Name;


a utility class that will extract X509Principal objects from X.509 certificates.


Use this in preference to trying to recreate a principal from a String, not all
DNs are what they should be, so it's best to leave them encoded where they
can be.

/**
 * a utility class that will extract X509Principal objects from X.509 certificates.
 * <p>
 * Use this in preference to trying to recreate a principal from a String, not all
 * DNs are what they should be, so it's best to leave them encoded where they
 * can be.
 */
public class PrincipalUtil
{
    
return the issuer of the given cert as an X509PrincipalObject.

/**
     * return the issuer of the given cert as an X509PrincipalObject.
     */
    public static X509Principal getIssuerX509Principal(
        X509Certificate cert)
        throws CertificateEncodingException
    {
        try
        {
            TBSCertificateStructure tbsCert = TBSCertificateStructure.getInstance(
                    ASN1Primitive.fromByteArray(cert.getTBSCertificate()));

            return new X509Principal(X509Name.getInstance(tbsCert.getIssuer()));
        }
        catch (IOException e)
        {
            throw new CertificateEncodingException(e.toString());
        }
    }

    
return the subject of the given cert as an X509PrincipalObject.

/**
     * return the subject of the given cert as an X509PrincipalObject.
     */
    public static X509Principal getSubjectX509Principal(
        X509Certificate cert)
        throws CertificateEncodingException
    {
        try
        {
            TBSCertificateStructure tbsCert = TBSCertificateStructure.getInstance(
                    ASN1Primitive.fromByteArray(cert.getTBSCertificate()));
            return new X509Principal(X509Name.getInstance(tbsCert.getSubject()));
        }
        catch (IOException e)
        {
            throw new CertificateEncodingException(e.toString());
        }
    }
    
    
return the issuer of the given CRL as an X509PrincipalObject.

/**
     * return the issuer of the given CRL as an X509PrincipalObject.
     */
    public static X509Principal getIssuerX509Principal(
        X509CRL crl)
        throws CRLException
    {
        try
        {
            TBSCertList tbsCertList = TBSCertList.getInstance(
                ASN1Primitive.fromByteArray(crl.getTBSCertList()));

            return new X509Principal(X509Name.getInstance(tbsCertList.getIssuer()));
        }
        catch (IOException e)
        {
            throw new CRLException(e.toString());
        }
    }
}