aesmaker.java

AES encryption and decryption tool, which can encrypt any string to a HEX number and decrypt in AES.

   import java.security.*;
   import javax.crypto.*;
   import javax.crypto.spec.*;
   import java.io.*;

   /**
   * 
   * This program generates a AES key, retrieves its raw bytes, and
   * then reinstantiates a AES key from the key bytes.
   * The reinstantiated key is used to initialize a AES cipher for
   * encryption and decryption.
   */

   public class AESMaker {

     /**
     * Turns array of bytes into string
     *
     * @param buf	Array of bytes to convert to hex string
     * @return	Generated hex string
     */
     public static String asHex (byte buf[]) {
      StringBuffer strbuf = new StringBuffer(buf.length * 2);
      int i;

      for (i = 0; i < buf.length; i++) {
       if (((int) buf[i] & 0xff) < 0x10)
	    strbuf.append("0");

       strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
      }

      return strbuf.toString();
     }

     public static void main(String[] args) throws Exception {

       String message="";

       // Get the KeyGenerator

       KeyGenerator kgen = KeyGenerator.getInstance("AES");
       kgen.init(128); // 192 and 256 bits may not be available


       // Generate the secret key specs.
       SecretKey skey = kgen.generateKey();
       byte[] raw = skey.getEncoded();
	   raw = ".intellitactics.".getBytes();

       SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");

       // Instantiate the cipher

       Cipher cipher = Cipher.getInstance("AES");

       cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

       byte[] encrypted = cipher.doFinal(message.getBytes());
       System.out.println("encrypted string: " + new String(encrypted));

	// 
	   raw = ".intellitactics.".getBytes();

        skeySpec = new SecretKeySpec(raw, "AES");

        cipher = Cipher.getInstance("AES");

       cipher.init(Cipher.DECRYPT_MODE, skeySpec);
       byte[] original = cipher.doFinal(encrypted);
       String originalString = new String(original);
       System.out.println("Original string: " + originalString + " " + asHex(original));
     }
   }