Question

I successfully make X.509 certificate from certificate request.

However, I need to insert CERT Path informatin in the X.509 certificate.

I know that I have to use CertPathBuilder method but I don’t know how to use it.

could you give me an code example that suitable for the following code?

import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;
import java.util.Date;
import java.util.Enumeration;
import org.bouncycastle.asn1.ASN1Set;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.pkcs.Attribute;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.x509.BasicConstraints;
import org.bouncycastle.asn1.x509.ExtendedKeyUsage;
import org.bouncycastle.asn1.x509.KeyPurposeId;
import org.bouncycastle.asn1.x509.KeyUsage;
import org.bouncycastle.asn1.x509.X509Extension;
import org.bouncycastle.asn1.x509.X509Extensions;
import org.bouncycastle.jce.PKCS10CertificationRequest;
import org.bouncycastle.openssl.PEMReader;
import org.bouncycastle.openssl.PEMWriter;
import org.bouncycastle.x509.X509V3CertificateGenerator;
import org.bouncycastle.x509.extension.AuthorityKeyIdentifierStructure;
import org.bouncycastle.x509.extension.SubjectKeyIdentifierStructure;
import chapter6.X509V1CreateExample;


//example of a basic CA
public class PKCS10CertCreateExample
{
    public static X509Certificate[] buildChain() throws Exception
    {

        PEMReader pRd = new PEMReader(
                     new InputStreamReader(
                         new FileInputStream("pkcs10.req")));

        PKCS10CertificationRequest request = (PKCS10CertificationRequest)pRd.readObject();





        //create a root certificate
        KeyPair rootPair=chapter6.Utils.generateRSAKeyPair();
    X509Certificate rootCert = X509V1CreateExample.generateV1Certificate(rootPair);

    //validate the certification request
    if(!request.verify("BC"))
    {
        System.out.println("request failed to verify!");
        System.exit(1);
    }

    //create the certificate using the information in the request
    X509V3CertificateGenerator certGen = new X509V3CertificateGenerator();

    certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis()));
    certGen.setIssuerDN(rootCert.getSubjectX500Principal());
    certGen.setNotBefore(new Date(System.currentTimeMillis()));
    certGen.setNotAfter(new Date(System.currentTimeMillis()+50000));
    certGen.setSubjectDN(request.getCertificationRequestInfo().getSubject());
    certGen.setPublicKey(request.getPublicKey("BC"));
    certGen.setSignatureAlgorithm("SHA256WithRSAEncryption");

    certGen.addExtension(X509Extensions.AuthorityKeyIdentifier, false, new AuthorityKeyIdentifierStructure(rootCert));
    certGen.addExtension(X509Extensions.SubjectKeyIdentifier, false, new SubjectKeyIdentifierStructure(request.getPublicKey("BC")));
    certGen.addExtension(X509Extensions.BasicConstraints, true, new BasicConstraints(false));
    //certGen.addExtension(X509Extensions.KeyUsage, true, new BasicConstraints(false));
    certGen.addExtension(X509Extensions.KeyUsage, true, new KeyUsage(KeyUsage.digitalSignature | KeyUsage.keyEncipherment));
    certGen.addExtension(X509Extensions.ExtendedKeyUsage, true, new ExtendedKeyUsage(KeyPurposeId.id_kp_serverAuth));

    //extract the extension request attribute
    ASN1Set attributes = request.getCertificationRequestInfo().getAttributes();

    for(int i=0;i!=attributes.size();i++)
    {
       Attribute attr = Attribute.getInstance(attributes.getObjectAt(i));

       //process extension request
       if(attr.getAttrType().equals(PKCSObjectIdentifiers.pkcs_9_at_extensionRequest))
       {
               X509Extensions extensions = X509Extensions.getInstance(attr.getAttrValues().getObjectAt(0));

               Enumeration<?> e = extensions.oids();
               while(e.hasMoreElements())
               {
                   DERObjectIdentifier oid = (DERObjectIdentifier)e.nextElement();
                   X509Extension ext = extensions.getExtension(oid);

                   certGen.addExtension(oid, ext.isCritical(), ext.getValue().getOctets());
               }   
           }       
       }
    X509Certificate issuedCert = certGen.generateX509Certificate(rootPair.getPrivate());
    return new X509Certificate[]{issuedCert, rootCert};
    }

    public static void pemEncodeToFile(String filename, Object obj, char[] password) throws Exception{
    PEMWriter pw = new PEMWriter(new FileWriter(filename));
       if (password != null && password.length > 0) {
           pw.writeObject(obj, "DESEDE", password, new SecureRandom());
       } else {
           pw.writeObject(obj);
       }
       pw.flush();
       pw.close();
    }

    public static void main(String[] args) throws Exception
    {
        X509Certificate[] chain = buildChain();
        PEMWriter pemWrt = new PEMWriter(new OutputStreamWriter(System.out));
        pemWrt.writeObject(chain[0]);
        pemEncodeToFile("pkcs10.pem", chain[0], null);
        pemWrt.close();

    }

}

Answer 1

The below code may help you

CertPathBuilder cpb = CertPathBuilder.getInstance("PKIX");
X509CertSelector certSelector = new X509CertSelector();
certSelector.setCertificate((X509Certificate) myKeyStore.getCertificate("mykey"));
PKIXBuilderParameters cpp = new PKIXBuilderParameters(trustAnchors, certSelector);
cpp.addCertStore(cs);
cpp.setRevocationEnabled(true);
cpp.setMaxPathLength(6);
cpp.setDate(new Date());

CertPathBuilderResult a = cpb.build(cpp);
CertPath certPath = a.getCertPath();