MainClass.java Source code

Introduction

Here is the source code for MainClass.java

Source

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.util.Date;

import sun.security.x509.AlgorithmId;
import sun.security.x509.CertificateAlgorithmId;
import sun.security.x509.CertificateIssuerName;
import sun.security.x509.CertificateSerialNumber;
import sun.security.x509.CertificateSubjectName;
import sun.security.x509.CertificateValidity;
import sun.security.x509.X500Name;
import sun.security.x509.X509CertImpl;
import sun.security.x509.X509CertInfo;

public class MainClass {
    public static void main(String[] args) throws Exception {
        String keystoreFile = "keyStoreFile.bin";
        String caAlias = "caAlias";
        String certToSignAlias = "cert";
        String newAlias = "newAlias";

        char[] password = new char[] { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h' };
        char[] caPassword = new char[] { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h' };
        char[] certPassword = new char[] { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h' };

        FileInputStream input = new FileInputStream(keystoreFile);
        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(input, password);
        input.close();

        PrivateKey caPrivateKey = (PrivateKey) keyStore.getKey(caAlias, caPassword);
        java.security.cert.Certificate caCert = keyStore.getCertificate(caAlias);

        byte[] encoded = caCert.getEncoded();
        X509CertImpl caCertImpl = new X509CertImpl(encoded);

        X509CertInfo caCertInfo = (X509CertInfo) caCertImpl.get(X509CertImpl.NAME + "." + X509CertImpl.INFO);

        X500Name issuer = (X500Name) caCertInfo.get(X509CertInfo.SUBJECT + "." + CertificateIssuerName.DN_NAME);

        java.security.cert.Certificate cert = keyStore.getCertificate(certToSignAlias);
        PrivateKey privateKey = (PrivateKey) keyStore.getKey(certToSignAlias, certPassword);
        encoded = cert.getEncoded();
        X509CertImpl certImpl = new X509CertImpl(encoded);
        X509CertInfo certInfo = (X509CertInfo) certImpl.get(X509CertImpl.NAME + "." + X509CertImpl.INFO);

        Date firstDate = new Date();
        Date lastDate = new Date(firstDate.getTime() + 365 * 24 * 60 * 60 * 1000L);
        CertificateValidity interval = new CertificateValidity(firstDate, lastDate);

        certInfo.set(X509CertInfo.VALIDITY, interval);

        certInfo.set(X509CertInfo.SERIAL_NUMBER, new CertificateSerialNumber((int) (firstDate.getTime() / 1000)));

        certInfo.set(X509CertInfo.ISSUER + "." + CertificateSubjectName.DN_NAME, issuer);

        AlgorithmId algorithm = new AlgorithmId(AlgorithmId.md5WithRSAEncryption_oid);
        certInfo.set(CertificateAlgorithmId.NAME + "." + CertificateAlgorithmId.ALGORITHM, algorithm);
        X509CertImpl newCert = new X509CertImpl(certInfo);

        newCert.sign(caPrivateKey, "MD5WithRSA");

        keyStore.setKeyEntry(newAlias, privateKey, certPassword, new java.security.cert.Certificate[] { newCert });

        FileOutputStream output = new FileOutputStream(keystoreFile);
        keyStore.store(output, password);
        output.close();

    }
}