CertificateSigner.java Source code

Introduction

Here is the source code for CertificateSigner.java

Source

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)
    
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
    
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
    
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import java.io.Console;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.security.KeyStore;
import java.security.Principal;
import java.security.PrivateKey;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Arrays;

import sun.security.x509.CertificateIssuerName;
import sun.security.x509.X500Name;
import sun.security.x509.X509CertImpl;
import sun.security.x509.X509CertInfo;

/**
 * This program signs a certificate, using the private key of another certificate in a keystore.
 * @version 1.01 2007-10-07
 * @author Cay Horstmann
 */
public class CertificateSigner {
    public static void main(String[] args) {
        String ksname = null; // the keystore name
        String alias = null; // the private key alias
        String inname = null; // the input file name
        String outname = null; // the output file name
        for (int i = 0; i < args.length; i += 2) {
            if (args[i].equals("-keystore"))
                ksname = args[i + 1];
            else if (args[i].equals("-alias"))
                alias = args[i + 1];
            else if (args[i].equals("-infile"))
                inname = args[i + 1];
            else if (args[i].equals("-outfile"))
                outname = args[i + 1];
            else
                usage();
        }

        if (ksname == null || alias == null || inname == null || outname == null)
            usage();

        try {
            Console console = System.console();
            if (console == null)
                error("No console");
            char[] password = console.readPassword("Keystore password: ");
            KeyStore store = KeyStore.getInstance("JKS", "SUN");
            InputStream in = new FileInputStream(ksname);
            store.load(in, password);
            Arrays.fill(password, ' ');
            in.close();

            char[] keyPassword = console.readPassword("Key password for %s: ", alias);
            PrivateKey issuerPrivateKey = (PrivateKey) store.getKey(alias, keyPassword);
            Arrays.fill(keyPassword, ' ');

            if (issuerPrivateKey == null)
                error("No such private key");

            in = new FileInputStream(inname);

            CertificateFactory factory = CertificateFactory.getInstance("X.509");

            X509Certificate inCert = (X509Certificate) factory.generateCertificate(in);
            in.close();
            byte[] inCertBytes = inCert.getTBSCertificate();

            X509Certificate issuerCert = (X509Certificate) store.getCertificate(alias);
            Principal issuer = issuerCert.getSubjectDN();
            String issuerSigAlg = issuerCert.getSigAlgName();

            FileOutputStream out = new FileOutputStream(outname);

            X509CertInfo info = new X509CertInfo(inCertBytes);
            info.set(X509CertInfo.ISSUER, new CertificateIssuerName((X500Name) issuer));

            X509CertImpl outCert = new X509CertImpl(info);
            outCert.sign(issuerPrivateKey, issuerSigAlg);
            outCert.derEncode(out);

            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Prints an error message and exits.
     * @param message the error message
     */
    public static void error(String message) {
        System.out.println(message);
        System.exit(1);
    }

    /**
     * Prints a usage message and exits.
     */
    public static void usage() {
        System.out.println("Usage: java CertificateSigner" + " -keystore keyStore -alias issuerKeyAlias"
                + " -infile inputFile -outfile outputFile");
        System.exit(1);
    }
}