JceSecretKeyTest.java - Secret Key Test Program

This section provides a quick tutorial example on how to write a sample program to generate a secret key for Blowfish, DES, or HmacMD5 encryption, save the secret key to a file, and read it back.

The following sample program shows you how to generate a secret key, write it a file, and read it back.

/**
 * JceSecretKeyTest.java
#- Copyright (c) 2013, HerongYang.com, All Rights Reserved.
 */
import java.io.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;
class JceSecretKeyTest {
   public static void main(String[] a) {
      if (a.length<3) {
         System.out.println("Usage:");
         System.out.println("java JceSecretKeyTest keySize output"
            +" algorithm");
         return;
      }
      int keySize = Integer.parseInt(a[0]);
      String output = a[1];
      String algorithm = a[2]; // Blowfish, DES, DESede, HmacMD5
      try {
         writeKey(keySize,output,algorithm);
         readKey(output,algorithm);
      } catch (Exception e) {
         System.out.println("Exception: "+e);
         return;
      }
   }
   private static void writeKey(int keySize, String output, 
         String algorithm) throws Exception {
      KeyGenerator kg = KeyGenerator.getInstance(algorithm);
      kg.init(keySize);
      System.out.println();
      System.out.println("KeyGenerator Object Info: ");
      System.out.println("Algorithm = "+kg.getAlgorithm());
      System.out.println("Provider = "+kg.getProvider());
      System.out.println("Key Size = "+keySize);
      System.out.println("toString = "+kg.toString());

      SecretKey ky = kg.generateKey();
      String fl = output+".key";
      FileOutputStream fos = new FileOutputStream(fl);
      byte[] kb = ky.getEncoded();
      fos.write(kb);
      fos.close();
      System.out.println();
      System.out.println("SecretKey Object Info: ");
      System.out.println("Algorithm = "+ky.getAlgorithm());
      System.out.println("Saved File = "+fl);
      System.out.println("Size = "+kb.length);
      System.out.println("Format = "+ky.getFormat());
      System.out.println("toString = "+ky.toString());
   }
   private static void readKey(String input, String algorithm) 
      throws Exception {
      String fl = input+".key";
      FileInputStream fis = new FileInputStream(fl);
      int kl = fis.available();
      byte[] kb = new byte[kl];
      fis.read(kb);
      fis.close();
      KeySpec ks = null;
      SecretKey ky = null;
      SecretKeyFactory kf = null;
      if (algorithm.equalsIgnoreCase("DES")) {
      	 ks = new DESKeySpec(kb);
         kf = SecretKeyFactory.getInstance("DES");
         ky = kf.generateSecret(ks);
      } else if (algorithm.equalsIgnoreCase("DESede")) {
      	 ks = new DESedeKeySpec(kb);
         kf = SecretKeyFactory.getInstance("DESede");
         ky = kf.generateSecret(ks);
      } else {
         ks = new SecretKeySpec(kb,algorithm);
         ky = new SecretKeySpec(kb,algorithm);
      }

      System.out.println();
      System.out.println("KeySpec Object Info: ");
      System.out.println("Saved File = "+fl);
      System.out.println("Length = "+kb.length);
      System.out.println("toString = "+ks.toString());

      System.out.println();
      System.out.println("SecretKey Object Info: ");
      System.out.println("Algorithm = "+ky.getAlgorithm());
      System.out.println("toString = "+ky.toString());
   }
}

Here is the result of my first test. It is done with JDK 1.6.

java -cp . JceSecretKeyTest 56 key1 Blowfish

KeyGenerator Object Info:
Algorithm = Blowfish
Provider = SunJCE version 1.6
Key Size = 56
toString = javax.crypto.KeyGenerator@b09e89

SecretKey Object Info:
Algorithm = Blowfish
Saved File = key1.key
Size = 7
Format = RAW
toString = javax.crypto.spec.SecretKeySpec@2685016e

KeySpec Object Info:
Saved File = key1.key
Length = 7
toString = javax.crypto.spec.SecretKeySpec@2685016e

SecretKey Object Info:
Algorithm = Blowfish
toString = javax.crypto.spec.SecretKeySpec@2685016e

The program seems to be working:

In the second test, I wants to try DES algorithm:

java -cp . JceSecretKeyTest 56 key2 DES

KeyGenerator Object Info:
Algorithm = DES
Provider = SunJCE version 1.6
Key Size = 56
toString = javax.crypto.KeyGenerator@b09e89

SecretKey Object Info:
Algorithm = DES
Saved File = key2.key
Size = 8
Format = RAW
toString = com.sun.crypto.provider.DESKey@fffe7965

KeySpec Object Info:
Saved File = key2.key
Length = 8
toString = javax.crypto.spec.DESKeySpec@a401c2

SecretKey Object Info:
Algorithm = DES
toString = com.sun.crypto.provider.DESKey@fffe7965

Of course, you can continue testing with DESede and HmacMD5.

Last update: 2013.

Table of Contents

 About This Book

 Cryptography Terminology

 Cryptography Basic Concepts

 Introduction to AES (Advanced Encryption Standard)

 Introduction to DES Algorithm

 DES Algorithm - Illustrated with Java Programs

 DES Algorithm Java Implementation

 DES Algorithm - Java Implementation in JDK JCE

 DES Encryption Operation Modes

 DES in Stream Cipher Modes

 PHP Implementation of DES - mcrypt

 Blowfish - 8-Byte Block Cipher

Secret Key Generation and Management

 javax.crypto.SecretKey - The Secret Key Interface

 javax.crypto.KeyGenerator - Generating Secret Keys

 Converting Secret Keys to and from Byte Arrays

JceSecretKeyTest.java - Secret Key Test Program

 Cipher - Secret Key Encryption and Decryption

 Introduction of RSA Algorithm

 RSA Implementation using java.math.BigInteger Class

 Introduction of DSA (Digital Signature Algorithm)

 Java Default Implementation of DSA

 Private key and Public Key Pair Generation

 PKCS#8/X.509 Private/Public Encoding Standards

 Cipher - Public Key Encryption and Decryption

 MD5 Mesasge Digest Algorithm

 SHA1 Mesasge Digest Algorithm

 OpenSSL Introduction and Installation

 OpenSSL Generating and Managing RSA Keys

 OpenSSL Managing Certificates

 OpenSSL Generating and Signing CSR

 OpenSSL Validating Certificate Path

 "keytool" and "keystore" from JDK

 "OpenSSL" Signing CSR Generated by "keytool"

 Migrating Keys from "keystore" to "OpenSSL" Key Files

 Certificate X.509 Standard and DER/PEM Formats

 Migrating Keys from "OpenSSL" Key Files to "keystore"

 Using Certificates in IE (Internet Explorer)

 Using Certificates in Firefox

 Using Certificates in Google Chrome

 Outdated Tutorials

 References

 PDF Printing Version