import sun.security.x509.CertificateSubjectName; //导入依赖的package包/类
/**
 * Create a self-signed X.509 Certificate.
 * From http://bfo.com/blog/2011/03/08/odds_and_ends_creating_a_new_x_509_certificate.html.
 *
 * @param dn the X.509 Distinguished Name, eg "CN=Test, L=London, C=GB"
 * @param pair the KeyPair
 * @param days how many days from now the Certificate is valid for
 * @param algorithm the signing algorithm, eg "SHA1withRSA"
 * @return the self-signed certificate
 * @throws IOException thrown if an IO error ocurred.
 * @throws GeneralSecurityException thrown if an Security error ocurred.
 */
public static X509Certificate generateCertificate(String dn, KeyPair pair,
                                                  int days, String algorithm)
  throws GeneralSecurityException, IOException {
  PrivateKey privkey = pair.getPrivate();
  X509CertInfo info = new X509CertInfo();
  Date from = new Date();
  Date to = new Date(from.getTime() + days * 86400000l);
  CertificateValidity interval = new CertificateValidity(from, to);
  BigInteger sn = new BigInteger(64, new SecureRandom());
  X500Name owner = new X500Name(dn);

  info.set(X509CertInfo.VALIDITY, interval);
  info.set(X509CertInfo.SERIAL_NUMBER, new CertificateSerialNumber(sn));
  info.set(X509CertInfo.SUBJECT, new CertificateSubjectName(owner));
  info.set(X509CertInfo.ISSUER, new CertificateIssuerName(owner));
  info.set(X509CertInfo.KEY, new CertificateX509Key(pair.getPublic()));
  info
    .set(X509CertInfo.VERSION, new CertificateVersion(CertificateVersion.V3));
  AlgorithmId algo = new AlgorithmId(AlgorithmId.md5WithRSAEncryption_oid);
  info.set(X509CertInfo.ALGORITHM_ID, new CertificateAlgorithmId(algo));

  // Sign the cert to identify the algorithm that's used.
  X509CertImpl cert = new X509CertImpl(info);
  cert.sign(privkey, algorithm);

  // Update the algorith, and resign.
  algo = (AlgorithmId) cert.get(X509CertImpl.SIG_ALG);
  info
    .set(CertificateAlgorithmId.NAME + "." + CertificateAlgorithmId.ALGORITHM,
         algo);
  cert = new X509CertImpl(info);
  cert.sign(privkey, algorithm);
  return cert;
}
 

import sun.security.x509.CertificateSubjectName; //导入依赖的package包/类
private static X509Certificate generateCert(
    String hostname, KeyPair kp, boolean isCertAuthority,
    PublicKey signerPublicKey, PrivateKey signerPrivateKey)
    throws IOException, CertificateException, NoSuchProviderException,
    NoSuchAlgorithmException, InvalidKeyException, SignatureException {
  X500Name issuer = new X500Name("CN=root" + issuerDirString);
  X500Name subject;
  if (hostname == null) {
    subject = issuer;
  } else {
    subject = new X500Name("CN=" + hostname + issuerDirString);
  }

  X509CertInfo info = new X509CertInfo();
  Date from = new Date();
  Date to = new Date(from.getTime() + 365 * 86400000l);
  CertificateValidity interval = new CertificateValidity(from, to);
  BigInteger sn = new BigInteger(64, new SecureRandom());

  info.set(X509CertInfo.VALIDITY, interval);
  info.set(X509CertInfo.SERIAL_NUMBER, new CertificateSerialNumber(sn));
  info.set(X509CertInfo.SUBJECT, new CertificateSubjectName(subject));
  info.set(X509CertInfo.ISSUER, new CertificateIssuerName(issuer));
  info.set(X509CertInfo.KEY, new CertificateX509Key(kp.getPublic()));
  info.set(X509CertInfo.VERSION, new CertificateVersion(CertificateVersion.V3));
  AlgorithmId algo = new AlgorithmId(AlgorithmId.md5WithRSAEncryption_oid);
  info.set(X509CertInfo.ALGORITHM_ID, new CertificateAlgorithmId(algo));

  // Sign the cert to identify the algorithm that's used.
  X509CertImpl cert = new X509CertImpl(info);
  cert.sign(signerPrivateKey, signingAlgorithm);

  // Update the algorithm, and resign.
  algo = (AlgorithmId)cert.get(X509CertImpl.SIG_ALG);
  info.set(CertificateAlgorithmId.NAME + "." + CertificateAlgorithmId.ALGORITHM, algo);
  cert = new X509CertImpl(info);
  cert.sign(signerPrivateKey, signingAlgorithm);
  return cert;
}
 

import sun.security.x509.CertificateSubjectName; //导入依赖的package包/类
/**
     * Create an X509 Certificate signed using SHA1withRSA with a 2048 bit key.
     * @param dname Domain Name to represent the certificate
     * @param notBefore The date by which the certificate starts being valid. Cannot be null.
     * @param validity The number of days the certificate is valid after notBefore.
     * @return An X509 certificate setup with properties using the specified parameters.
     * @throws Exception
     */
    public static X509Certificate createCert(String dname, Date notBefore, int validity)
            throws Exception {
        int keysize = 2048;
        String keyAlgName = "RSA";
        String sigAlgName = "SHA1withRSA";

        if (dname == null)
            throw new Exception("Required DN is null. Please specify cert Domain Name via dname");
        if (notBefore == null)
            throw new Exception("Required start date is null. Please specify the date at which the cert is valid via notBefore");
        if (validity < 0)
            throw new Exception("Required validity is negative. Please specify the number of days for which the cert is valid after the start date.");

        // KeyTool#doGenKeyPair
        X500Name x500Name = new X500Name(dname);

        KeyPair keyPair = new KeyPair(keyAlgName, sigAlgName, keysize);
        PrivateKey privKey = keyPair.getPrivateKey();

        X509Certificate oldCert = keyPair.getSelfCertificate(x500Name, notBefore, validity);

        // KeyTool#doSelfCert
        byte[] encoded = oldCert.getEncoded();
        X509CertImpl certImpl = new X509CertImpl(encoded);
        X509CertInfo certInfo = (X509CertInfo) certImpl.get(X509CertImpl.NAME
                + "." + X509CertImpl.INFO);

        Date notAfter = new Date(notBefore.getTime() + validity*1000L*24L*60L*60L);

        CertificateValidity interval = new CertificateValidity(notBefore,
                notAfter);

        certInfo.set(X509CertInfo.VALIDITY, interval);
        certInfo.set(X509CertInfo.SERIAL_NUMBER, new CertificateSerialNumber(
                    new java.util.Random().nextInt() & 0x7fffffff));
        certInfo.set(X509CertInfo.SUBJECT + "." + CertificateSubjectName.DN_NAME, x500Name);
        certInfo.set(X509CertInfo.ISSUER + "." + CertificateIssuerName.DN_NAME, x500Name);

        // The inner and outer signature algorithms have to match.
        // The way we achieve that is really ugly, but there seems to be no
        // other solution: We first sign the cert, then retrieve the
        // outer sigalg and use it to set the inner sigalg
        X509CertImpl newCert = new X509CertImpl(certInfo);
        newCert.sign(privKey, sigAlgName);
        AlgorithmId sigAlgid = (AlgorithmId)newCert.get(X509CertImpl.SIG_ALG);
        certInfo.set(CertificateAlgorithmId.NAME + "." + CertificateAlgorithmId.ALGORITHM, sigAlgid);

        certInfo.set(X509CertInfo.VERSION, new CertificateVersion(CertificateVersion.V3));

        // FIXME Figure out extensions
//        CertificateExtensions ext = createV3Extensions(
//                null,
//                (CertificateExtensions)certInfo.get(X509CertInfo.EXTENSIONS),
//                v3ext,
//                oldCert.getPublicKey(),
//                null);
//        certInfo.set(X509CertInfo.EXTENSIONS, ext);

        newCert = new X509CertImpl(certInfo);
        newCert.sign(privKey, sigAlgName);

        return newCert;
    }