FetchCertificate.java

package com.jd;

import java.io.*;
import java.net.URL;

import java.security.*;
import java.security.cert.*;

import javax.net.ssl.*;

public class FetchCertificate {

    public static void main(String[] args) throws Exception {
	String host;
	int port;
	char[] passphrase;
	printBanner();
	if ((args.length == 1) || (args.length == 2)) {
	    String[] c = args[0].split(":");
	    host = c[0];
	    port = (c.length == 1) ? 443 : Integer.parseInt(c[1]);
	    String p = (args.length == 1) ? "changeit" : args[1];
	    passphrase = p.toCharArray();
	} else {
	    System.out.println("Steps to execute the jar");
	    System.out.println("-------------------------------------------------------");
	    System.out.println("java -jar <name-of-the-jar.jar> <RDS-host>:<SSL_PORT>");
	    System.out.println("-------------------------------------------------------");
		System.out.println("-------------------------------------------------------");
	    return;
	}

	File file = new File("jssecacerts");
	if (file.isFile() == false) {
	    char SEP = File.separatorChar;
	    File dir = new File(System.getProperty("java.home") + SEP
		    + "lib" + SEP + "security");
	    file = new File(dir, "jssecacerts");
	    if (file.isFile() == false) {
		file = new File(dir, "cacerts");
	    }
	}
	System.out.println("Loading KeyStore " + file + "...");
	InputStream in = new FileInputStream(file);
	KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
	ks.load(in, passphrase);
	in.close();

	SSLContext context = SSLContext.getInstance("TLS");
	TrustManagerFactory tmf =
	    TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
	tmf.init(ks);
	X509TrustManager defaultTrustManager = (X509TrustManager)tmf.getTrustManagers()[0];
	SavingTrustManager tm = new SavingTrustManager(defaultTrustManager);
	context.init(null, new TrustManager[] {tm}, null);
	SSLSocketFactory factory = context.getSocketFactory();

	System.out.println("Opening connection to " + host + ":" + port + "...");
	SSLSocket socket = (SSLSocket)factory.createSocket(host, port);
	socket.setSoTimeout(10000);
	try {
	    System.out.println("Starting SSL handshake...");
	    socket.startHandshake();
	    socket.close();
	    System.out.println();
	    System.out.println("No errors, certificate is already trusted");
	} catch (SSLException e) {
	    System.out.println();
	    e.printStackTrace(System.out);
	}

	X509Certificate[] chain = tm.chain;
	if (chain == null) {
	    System.out.println("Could not obtain server certificate chain");
	    return;
	}

	BufferedReader reader =
		new BufferedReader(new InputStreamReader(System.in));

	System.out.println();
	System.out.println("Server sent " + chain.length + " certificate(s):");
	System.out.println();
	MessageDigest sha1 = MessageDigest.getInstance("SHA1");
	MessageDigest md5 = MessageDigest.getInstance("MD5");
	for (int i = 0; i < chain.length; i++) {
	    X509Certificate cert = chain[i];
	    System.out.println
	    	(" " + (i + 1) + " Subject " + cert.getSubjectDN());
	    System.out.println("   Issuer  " + cert.getIssuerDN());
	    sha1.update(cert.getEncoded());
	    System.out.println("   sha1    " + toHexString(sha1.digest()));
	    md5.update(cert.getEncoded());
	    System.out.println("   md5     " + toHexString(md5.digest()));
	    System.out.println();
	}

	System.out.println("Enter certificate to add to trusted keystore or 'q' to quit: [1]");
	String line = reader.readLine().trim();
	int k;
	try {
	    k = (line.length() == 0) ? 0 : Integer.parseInt(line) - 1;
	} catch (NumberFormatException e) {
	    System.out.println("KeyStore not changed");
	    return;
	}

	X509Certificate cert = chain[k];
	String alias = host + "-" + (k + 1);
	ks.setCertificateEntry(alias, cert);

	OutputStream out = new FileOutputStream("jssecacerts");
	ks.store(out, passphrase);
	out.close();

	System.out.println();
	System.out.println(cert);
	System.out.println();
	System.out.println
		("Added certificate to keystore 'jssecacerts' using alias '"
		+ alias + "'");
    }

    private static final char[] HEXDIGITS = "0123456789abcdef".toCharArray();

    private static String toHexString(byte[] bytes) {
	StringBuilder sb = new StringBuilder(bytes.length * 3);
	for (int b : bytes) {
	    b &= 0xff;
	    sb.append(HEXDIGITS[b >> 4]);
	    sb.append(HEXDIGITS[b & 15]);
	    sb.append(' ');
	}
	return sb.toString();
    }
    
    public static void printBanner(){
		System.out.println("---------------------------------------------------------------------------------------");
		System.out.println("Tool to generate Keystore imported with the latest certificates authorised to a domain.");
		System.out.println("---------------------------------------------------------------------------------------");
		System.out.println("By: Soumyadeep Biswas");
		System.out.println("Contact: soumyadeep009@gmail.com");
		System.out.println("---------------------------------------------------------------------------------------");
    }

    private static class SavingTrustManager implements X509TrustManager {

	private final X509TrustManager tm;
	private X509Certificate[] chain;

	SavingTrustManager(X509TrustManager tm) {
	    this.tm = tm;
	}

	public X509Certificate[] getAcceptedIssuers() {
	    throw new UnsupportedOperationException();
	}

	public void checkClientTrusted(X509Certificate[] chain, String authType)
		throws CertificateException {
	    throw new UnsupportedOperationException();
	}

	public void checkServerTrusted(X509Certificate[] chain, String authType)
		throws CertificateException {
	    this.chain = chain;
	    tm.checkServerTrusted(chain, authType);
	}
    }

}